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. 2025 Oct 6;20(10):e0333696. doi: 10.1371/journal.pone.0333696

Drone-based medication delivery for rural, flood-prone coastal communities

Yin-Hsuen Chen 1,*, Amro M El-Adle 2, Kevin J O’Brien 3, Taylor Wentworth 4, Heather G Richter 5,6
Editor: Zeashan Hameed Khan7
PMCID: PMC12500137  PMID: 41052127

Abstract

Access to healthcare remains a critical challenge for rural populations, particularly in flood-prone coastal communities where transportation barriers limit access to essential medical services. This study evaluates the effectiveness of drone-based medication delivery in improving healthcare accessibility for vulnerable populations on Virginia’s Eastern Shore. Compared to traditional personal vehicle travel, drone delivery reduced trip times from up to 50 minutes to under 10 minutes for more than 80% of the population, including elderly patients. Using publicly available datasets, we developed two transportation vulnerability indices that incorporate age, travel time, and flood risk to prioritize patients for drone-based pharmaceutical delivery. These indices were examined using Getis-Ord Gi* spatial analysis, which identified statistically significant clusters of high-need patients, particularly around the northernmost drone station. The results reveal that elderly residents in remote, low-lying areas are especially vulnerable to missed prescriptions due to both transportation barriers and flooding. Our approach demonstrates how drone delivery can reduce healthcare access disparities while offering a scalable and resilient framework for other medically underserved regions, especially under time or resource constraints.

1. Introduction

Access to healthcare remains a significant challenge for remote and underserved coastal communities, particularly in flood-prone regions where transportation disruptions can delay or prevent the delivery of essential medications. This barrier disproportionately affects vulnerable populations, exacerbating health disparities and limiting healthcare accessibility. Travel by traditional personal vehicles to retrieve medication may not meet the needs of these communities due to infrastructure limitations, geographic isolation [1], and the increasing frequency of extreme weather events [2]. Unmanned aerial vehicles (UAVs), or drones [3], present a promising alternative for overcoming these logistical challenges by providing rapid, reliable, and scalable medication delivery [4]. However, the potential of drone-based systems to enhance healthcare access, particularly for vulnerable coastal communities frequently affected by flooding due to high tides [5,6], and tropical cyclones [7] has yet to be fully investigated. Addressing this gap necessitates a comprehensive evaluation of drone delivery systems, including time savings, geographic coverage, and the identification of high-priority areas with the greatest need for intervention, particularly those that are vulnerability hot spots.

Healthcare access remains a major challenge for rural communities. In the rural U.S., where over 46 million people reside, approximately 80% are medically underserved, facing complex barriers to healthcare access [8]. Berenbrok, Tang [9] investigated household access to pharmacies across U.S. counties using ArcGIS Network Analyst and classified counties by Rural-Urban Continuum Codes (RUCC). Accessibility varied markedly: 58.6% of residents in large metropolitan areas lived within 1.6 kilometers of a pharmacy, compared with only 26.9% in rural areas. Worldwide, studies have consistently shown significant disparities in access to pharmaceutical services between urban and rural communities (e.g., Todd, Copeland [10], Law, Heard [11]). Compared to their urban counterparts, rural residents often experience lower incomes, reduced healthcare literacy, limited broadband access for telehealth services, and inadequate transportation options for healthcare-related trips [8]. Tharumia Jagadeesan and Wirtz [12] reviewed studies on pharmacy accessibility and found that 11 of these examined pharmacy density in relation to urban and rural populations. All of the reviewed studies consistently reported that urban populations have better access to pharmacies compared to rural populations. These findings highlight the persistent disparities in healthcare access between rural and urban populations, underscoring the urgent need for innovative solutions to improve pharmacy accessibility in underserved rural communities.

Reliable transportation is essential for accessing healthcare services, and its absence has been linked to missed or delayed medical appointments and increased healthcare costs [13,14]. Studies highlight that elderly rural populations are particularly vulnerable, as they face compound challenges such as limited public transportation, lack of a driver’s license, and financial constraints [1,15]. For example, Shirgaokar, Dobbs [16] found that non-driving status, low income, poor health, and disability significantly restricted healthcare-related travel among rural elderly populations. Similarly, Ranković Plazinić and Jović [17], in a study of 346 elderly respondents in rural Serbia, found that mobility levels were generally low, but accessibility varied among settlements, with age and possession of a driver’s license emerging as key factors influencing mobility. Personal vehicles are essential for mobility and access to critical services in rural communities, particularly for older adults. A national study of individuals aged 65–79 found that rural residents were 7% more likely than their urban and suburban peers to emphasize the importance of driving [18], underscoring their reliance on personal transportation. In rural North Carolina, individuals with a driver’s license made 2.29 times more healthcare visits, while those with access to family or friends for transportation had 1.58 times more visits [19], highlighting how transportation directly affects healthcare access. Yet, despite this heavy reliance, older drivers in rural areas face disproportionate barriers due to chronic health conditions, physical impairments, and age-related declines in driving ability [20,21]. Without viable transportation alternatives, these challenges severely limit rural seniors’ access to care and independence.

The transportation challenges are particularly acute in flood-prone coastal communities, where geographic isolation, rising sea levels, and frequent flooding events further restrict access to essential healthcare services [7,22,23]. Transportation network disruptions caused by extreme weather events exacerbate these accessibility issues. For instance, Hierink, Rodrigues [7] found that Cyclones Idai and Kenneth in Mozambique reduced healthcare accessibility from 79% to 53% and from 82% to 72%, respectively. Similarly, Tomio, Sato [24] examined the impact of flooding in Kagoshima, Japan, and reported that up to 23% of evacuated patients with chronic conditions experienced medication interruptions, with those aged 75 and older being particularly affected. These findings highlight the critical need for alternative delivery methods to ensure continuity of care during and after flood events. Given the vulnerability of traditional transportation methods to flooding and extreme weather, alternative solutions are essential to maintaining healthcare access during disruptions.

Autonomous drone delivery systems have emerged as a promising option, offering a reliable method for delivering medical supplies to isolated populations [4,25]. In the U.S., several private companies have received regulatory approval to provide drone-based delivery services in select locations [26], demonstrating the potential for this technology to improve healthcare accessibility in vulnerable regions. A notable milestone occurred in 2015, when the first government-approved medical drone delivery was conducted in Wise, Virginia. This event demonstrated the feasibility of using drones to navigate rugged, rural terrain and highlighted their potential for providing faster, more dependable access to critical supplies in hard-to-reach communities [27]. Later, two U.S.-based drone companies, Volansi and Zipline, piloted vaccine and medication deliveries in North Carolina and Arkansas [28].

Studies have further highlighted drones’ ability to transport medicine, vaccines, and emergency medical supplies, with key benefits such as minimizing infection risk through reduced human contact and improving emergency response times [29,30]. Additionally, Haidari, Brown [31] found that drone-based vaccine distribution increased availability while reducing costs compared to traditional land-based transport. Regarding delivery costs, an analysis by PricewaterhouseCoopers (PwC) estimates that each drone delivery ranges from $6 to $25 per trip, with costs decreasing as the number of drones overseen by a single pilot increases [32]. In practice, Walmart currently charges $19.99 per delivery in the U.S., while Manna customer in Ireland pay about $4 per delivery [33,34].

Although drones offer a promising solution for overcoming these logistical challenges by providing rapid, reliable, and scalable medication delivery [4], research on their routine use for non-emergency healthcare services remains limited. Existing studies have primarily focused on emergency scenarios, such as delivering automated external defibrillators [35] or distributing vaccines during pandemics [36], leaving a critical gap in understanding the broader, sustained impact of drone-based deliveries on healthcare access in rural and flood-prone regions. While several studies have compared delivery methods such as electric vehicles, trucks, and bicycles with drones (e.g., Garus, Christidis [37], Comi and Savchenko [38]), few have examined personal vehicle travel against drone delivery, a comparison that could yield critical insights for designing effective drone delivery strategies in rural, flood prone communities. Nationwide studies, such as Berenbrok, Tang [9], have analyzed pharmacy accessibility disparities across the U.S. using household-level network analysis with a 1% random sample. Similarly, Sharareh, Zheutlin [39] employed population-weighted census tract centroid to estimate driving times to community pharmacies at a national scale. While valuable, these analyses remain coarse in scale, highlighting the need for more comprehensive, locally focused studies to capture finer-grained variations in accessibility. Additionally, frameworks like Kim, Lim [25] lack direct comparisons between drones and traditional transportation methods, preventing a comprehensive evaluation of drone efficiency, geographic reach, and service reliability. Together, this gap underscores the urgent need for a comprehensive investigation into the role of drones in delivering essential medical supplies to vulnerable rural populations.

This study evaluates the effectiveness of drone-based delivery systems in enhancing healthcare access for flood-prone coastal communities, with a focus on serving the most vulnerable populations. The primary research objective is to develop and assess a scalable framework that integrates drone-based delivery, spatial vulnerability analysis, and operational modeling to improve equitable healthcare access in disaster-prone rural regions. Using Virginia’s Eastern Shore (hereafter ES) as a case study, this study compares traditional vehicle-based travel with drone-based delivery systems in flood-prone coastal communities and evaluates patient vulnerability. Travel times were estimated for both modes, and two vulnerability indices—one incorporating age and travel time (VAT) and another adding flood impacts (VATF)—were used to identify high-risk populations. Hotspot analysis guided prioritization of drone stations, demonstrating how drones can improve timely medication access for the most vulnerable residents. This study contributes to healthcare accessibility and disaster-resilient delivery systems in three ways: by quantifying the time savings of drone-based medication delivery over traditional vehicle travel, by developing spatial vulnerability indices to identify high-need patients, and by evaluating drone hub performance to guide effective placement and resource allocation. Together, these findings demonstrate the feasibility and strategic value of drone networks as a resilient, equitable alternative to vehicle-dependent systems, offering a scalable framework for application in similar regions worldwide.

In what follows, Section 2 describes the study area and methodology, Section 3 presents the results of our analysis, Section 4 discusses these findings and the limitations, and Section 5 concludes with directions for future work.

2. Methodology

2.1 Study site

The ES forms the southernmost part of the Delmarva Peninsula, separated from the mainland by the Chesapeake Bay (Fig 1). The eastern portion features a complex of lagoons and barrier islands along the Atlantic Ocean, while the central and western parts are well-drained, with elevations reaching up to 17 m above sea level [40]. The peninsula’s north–south axis follows a prominent local ridge, where U.S. Route 13 connects various villages and towns. The ES consists of two counties, Accomack and Northampton, with the only direct connection to mainland Virginia being the 27 km Chesapeake Bay Bridge Tunnel. To the northwest, Tangier Island is an isolated community only accessible by boat or plane, where medical deliveries typically require two to three days. This geographic isolation compounds healthcare access across the ES, particularly for remote communities like Tangier Island. Additionally, the risk of flooding and sea-level rise [41] exacerbates existing barriers to healthcare services, which may be especially important during emergencies [42]. Only seven pharmacies serve patients across almost 2,608 km2 of the ES (Fig 1b). There is one bus line along a single main road, which provides limited access to smaller rural roads [43].

Fig 1. A side-by-side map showing the 100-year flood zone along the elevation relief of Eastern Shore (ES) of Virgina (a), as well as the locations of drone stations, pharmacies, and the road network with elevation relief (b).

Fig 1

The inset map (c) highlights the study area’s relative location on the Eastern Coast of the U.S., indicated by a red rectangle.

The ES was selected as our case study due to its rural nature, high flood exposure, and significant transportation barriers to healthcare. The region is designated as both a medically underserved area (MUA) and a health professional shortage area (HPSA) by the federal government [44]. Additionally, the ES is classified as a historically disadvantaged community (HDC), having been marginalized by underinvestment and overburdened by multiple disadvantage indicators, including health, transportation, and environmental resilience [45]. A recent health assessment revealed that more than 50% of residents identified transportation as the primary barrier to healthcare access [46]. Households on the ES also face lower median incomes, higher poverty rates, and higher rates of households lacking a personal vehicle compared to state and national averages [47]. Table 1 provides a comparison of community rates for hypertension, lack of health insurance, and limited access to broadband internet. Given that hypertension is a major healthcare concern in the region, patients with higher prevalence of hypertension were selected for the pilot study [46]. Additionally, flooding was incorporated as a key transportation barrier to assess community resilience.

Table 1. A comparison of socioeconomic indicators on the ES with state and national levels.

Indicator Eastern Shore of Virginia Virginia United States
Median household income (USD) $45,000 $80,615 $70,784
Households living below the poverty line (Percent) 18.0% 10.6% 11.5%
Persons 65 years and older (Percent) 21.5% 16.0% 16.8%
Population density (persons per km2) 170.9 524.7 240.9
Prevalence of hypertension (Percent) 40.0% 32.5% 32.6%
High school graduate, persons aged 25 and older (Percent) 80.0% 89.0% 88.5%
Persons aged 18 and older lacking health insurance (Percent) 21.0% 8.5% 11.0%
Households without a vehicle (Percent) 10.0% 7.0% 8.5%
Households with Broadband Internet Subscription (Percent) 65.0% 80.0% 85.0%

2.2 Data acquisition and pre-processing

Access to medical data is often limited due to privacy concerns, making secure data management costly [48,49]. In the U.S., healthcare data brokers charge from $0.05 to $125 per record, and entire electronic health record databases can cost up to $500,000 [50]. Alternatively, public datasets, such as those from the U.S. Census, offer free, standardized data. Studies like Kolak, Bhatt [51] have used public data to identify vulnerable populations based on social determinants of health, allowing for essential analysis without relying on medical records. To ensure the privacy of patient healthcare records, our analysis relies entirely on multi-sector public datasets. This approach not only safeguards patient health information but also renders the analytical tools amenable to diverse regions.

Geospatial data were obtained from various local, state, and federal agencies (Table 2) and processed to cover the ES, and ESRI® ArcGIS Pro 3.X was used to conduct the geospatial analyses. The coordinates of seven pharmacies and five drone automation stations on the ES were compiled for analysis. The pharmacies include Walgreens, CVS, Walmart, Rayfield Pharmacy Cape Charles, Rayfield Pharmacy Nassawadox, Atlantic Community Pharmacy Oak Hall, and H & H Pharmacy Chincoteague. The drone automation stations are Riverside Shore Memorial Hospital, Riverside Cape Charles Medical Center, Riverside Eastern Shore Family Medicine, Riverside Shore Medical Center at Metompkin, and Riverside Tangier Medical Center (Fig 1b). These stations are part of Riverside Health System, a leading healthcare provider on the ES.

Table 2. Geospatial data utilized in analysis.

Data Latest updatea Source
Road centerlines June 2024 Virginia Geographic Information Network (https://vgin.vdem.virginia.gov/pages/clearinghouse)
Parcel July 2024; June 2024 Accomack County GIS Data (https://accomack-county-virginia-open-data-portal-accomack.hub.arcgis.com/); Virginia Geographic Information Network (https://vgin.vdem.virginia.gov/pages/clearinghouse)
Building footprint June 2024 Virginia Geographic Information Network (https://vgin.vdem.virginia.gov/pages/clearinghouse)
UAS facility map data July 2024 Federal Aviation Administration (https://hub.arcgis.com/datasets/faa::faa-uas-facilitymap-data/about)
Decennial demographic and housing characteristics data 2020 Explore Census Data (https://data.census.gov/)
National land cover database 2021 Earth Resources Observation and Science Center (https://www.mrlc.gov/data/nlcd-land-cover-conus-all-years)
Flood insurance map 2015 (Accomack County), 2016 (Northampton County) Flood Map Service Center (https://msc.fema.gov/portal/advanceSearch)

aUpdate dates are listed based on the acquisition date; sources may have more recent updates.

To improve the accuracy of population segment computation, we utilized the Intelligent Dasymetric Mapping (IDM) Toolbox developed by the Environmental Protection Agency (EPA) [52,53]. We imported the IDM Toolbox [54] into ArcGIS Pro. The IDM tool requires input layers, including the census block, land use/land cover, and uninhabitable areas. The census block layer provides population data, which was used to calculate not only the total population but also the population of individuals aged 60 and older. This distinction is essential because the older population has a higher prevalence of hypertension: according to the 2017–2018 studies [55], hypertension affects 22.4% of adults aged 18–39, and 74.5% of those aged 60 and above.

The land use/land cover layer served as an ancillary raster layer to determine the computational methods, which included preset density, sampling, or intelligent areal weighting [52]. We created a JSON file to specify which land cover classes were assigned a preset density of zero. These classes include land cover and land use for open water, barren land, deciduous forest, evergreen forest, mixed forest, shrub/scrub, grassland/herbaceous, pasture/hay, cultivated crops, woody wetlands, and emergent herbaceous wetlands, respectively. Additionally, an uninhabitable layer was created using the method developed by Baynes, Neale [54] to exclude specific areas from the dasymetric computation. These uninhabitable areas include government-owned lands, major road networks, and commercial land parcels. The output from the IDM toolbox is in raster format, where each pixel’s value indicates the estimated population at that specific location. Incorporating these layers and computational methods enhanced the precision of population distribution estimates, particularly for older patients.

Building footprints were also used to identify potential patient sites. Due to the absence of zoning information, building footprint data from the uninhabitable layer was excluded [54]. The building footprints were overlaid with the parcel layer, and each building footprint was assigned a parcel identification number. Within each parcel, the largest building identified was assumed to be the primary residence of the patient. The results of the dasymetric mapping were used to perform zonal statistics, enabling the estimation of population within various travel zones. Additionally, building footprint data were used in the network analysis to identify precise locations of potential patients. This combination of methods ensured an accurate assessment of both population distribution and patient locations within the study area, facilitating better planning and resource management. Finally, due to its proximity to a small airfield, the Federal Aviation Administration (FAA) has designated this area of the ES a restricted zone for drones. As a result, residents of this area, totaling 7,749 individuals, including 2,943 aged 60 and older, are excluded from the analysis.

2.3 Operational and regulatory considerations of medication delivery by drone

Prior studies have suggested partnerships between healthcare professionals, transportation experts, and community liaisons to overcome complex transportation barriers [56,57]. This case study involves collaboration among local stakeholders, healthcare professionals, drone delivery providers, and academic researchers. This transdisciplinary approach addresses the complexity of transportation barriers and offers data-driven insights into optimizing drone delivery networks. The organizations partnering for this study are shown in Table 3 alongside their role in the project [58]. Given the novelty of drone delivery technology and the importance of delivering prescription medications safely, this section describes important regulatory, institutional, and operational considerations.

Table 3. Overview of partner organizations.

Organization Role
Accomack-Northampton Planning District Commission Community Engagement/Public Outreach
DroneUp Technical and Service Provider
Old Dominion University/Virginia Institute for Spaceflight & Autonomy Project Management/Data Modeling
Riverside Health Medical Service Provider
Virginia Innovation Partnership Corporation Funding Support

From a delivery hub, drones may fly to patient locations more than 6 miles away, thereby avoiding traffic, or the need to navigate rural roads that may be flooded. As shown in Fig 2, drone delivery allows patients to retrieve medications from their lawn or backyard, rather than needing to travel to a hospital or pharmacy via public transportation or personal vehicle. This autonomous delivery mechanism may be especially beneficial for patients managing multiple conditions with frequent medication refills, or patients who may not be able to drive. While drone delivery platforms require infrastructure investments, those fixed costs can be spread over a large volume of deliveries, reducing the cost per delivery.

Fig 2. Stages of drone delivery of hypertension medications to patients on the Eastern Shore of Virginia: (a) Medications are prepared and packaged by a healthcare professional; (b) the drone is loaded with the package and a charged battery; (c) the medication is lowered to the patient’s residence using a winch line; (d) the package is left on the lawn for the patient to retrieve.

Fig 2

Photos Courtesy of Virginia Institute for Spaceflight & Autonomy as part of the Elevating Healthcare Access Project.

Although the procedures outlined here were used on the ES for this specific case study, they may be generalized more broadly in similar communities. As shown in Fig 3, deliveries commence at a drone hub, at which qualified healthcare workers pack a prescription into a carton to be carried aboard the drone [58]. To meet state and federal regulations, DroneUp and Riverside Health use a validation system that ensures not only that the hypertension prescriptions are suitable for drone delivery, but also that the patient address is cross-validated prior to drone launch. While being loaded with a parcel, the drone’s battery is also swapped with a freshly-charged unit to permit maximum flight time. For the earliest stage of the partnership described in this article, DroneUp received permission from the FAA. Each drone is piloted remotely by a single pilot. The drones are equipped with cellular communications equipment to permit remote piloting [58]. DroneUp also performs extensive scans of the flight paths in advance of delivery operations to create a digital twin of the environment to ensure that in case the drones lose connectivity, they can land safely in an emergency. Finally, drones are designed to launch from and to return to any hub in the DroneUp network, rather than being required to return to the hub from which the drone launched. This allows the drones to fly for a longer range as compared with a system in which each drone must return to the same hub from which it launched [58].

Fig 3. Conceptual illustration of medication delivery by autonomous drones.

Fig 3

Adapted from Federal Aviation Administration [59].

For the flights described in this article, DroneUp deployed a visual observer to maintain line of sight of the drone at all times as a precaution. For future deployments, DroneUp has applied for FAA approval to fly drones beyond the visual line of sight, eliminating the need for a visual observer. The approval would also permit a single remote pilot to operate several drones simultaneously [58].

2.4 Comparison of travel zones

Given patient locations, this subsection describes tools that delineate travel time zones for pharmaceutical trips conducted via personal vehicle, as compared with drone-based deliveries. Personal vehicular trips consider round-trip travel times, since the patient would be required to drive to the pharmacy, then to drive home with the prescription medication. But for drone delivery, only one-way travel times from the nearest drone station to the patient’s address are computed, since the medication is delivered upon the drone’s arrival to the patient’s address.

To estimate travel time for vehicular trips, we first constructed a Network Dataset, accounting for road hierarchy and travel speed (in minutes), the latter of which was determined by dividing the road length by the speed limit. Road networks were classified into three hierarchical levels: Level 1 included major US and Virginia highways; Level 2 included local main arteries; and Level 3 included local secondary arteries and others (Fig 1b). This hierarchy system assumes that drivers are more likely to utilize major roads with higher speed limits [60]. Within the Network Dataset, the Service Area function [61] was used to generate travel time zones based on the location of pharmacies. The Service Area was solved by specifying multiple travel times as cutoff values, with 5-minute intervals. Since the travel time was computed for one-way travel, the values for time zones were doubled to represent round-trip intervals of 10 minutes.

To determine the one-way delivery time for drones, we initially generated a Euclidean distance layer to calculate the distance from proposed drone hub sites, assuming direct flight paths towards the recipients. Subsequently, the estimated delivery time in minutes was computed as Eq 1:

Travel Time (minutes)=[Tt+Td+(DistDmps)]/60 (1)

In this equation, Tt and Td represent the estimated takeoff and drop-off times, which were fixed at 35 seconds and 45 seconds, based on operational data provided by DroneUp. Dist refers to the straight-line (Euclidean) distance between the drone hub and the patient’s location, measured in meters. Dmps is the drone’s flying speed, expressed in meters per second; for this study, we used a value of 22.35 m/s (approximately 50 mph). Dividing the sum by 60 converts the total time from seconds to minutes, yielding the estimated one-way delivery time for each location. While the outcome of drone travel time is represented with continuous values, we reclassified the raster into 10-minute intervals to facilitate comparison with car travel zones. Once both travel zones were delineated, we aggregated the population layers (total and 60+) within each travel zone using the Zonal Statistics function. This approach allows for a more straightforward analysis of travel efficiency between drones and traditional personal vehicles, providing valuable insights for optimizing transportation strategies.

2.5 Assessing patient vulnerability

Patient age, vehicular travel time to the nearest pharmacy, and flood interruption were used to assess vulnerability. We used building footprint data to represent patient locations. To determine the age of potential patients, we utilized 2020 census block data (Table 2), which provides population counts across different age groups for both males and females. We aggregated the population of individuals aged 60 and older from both genders and calculated the percentage of this age group relative to the total population in each census block. These percentage values were then assigned to each building footprint based on its intersection with the corresponding census block. For personal vehicle travel time, we used the Closest Facility function to calculate the travel time from each building footprint to the nearest pharmacy. We employed the Network Database created from the personal vehicle travel zone analysis as the travel model and imported the building footprint and pharmacy locations as incidents and facilities, respectively, for the analysis. The result provided the shortest driving routes along the road network, measured in minutes. We then joined the driving time data with the building footprint data using the unique incident identification numbers.

To assess the impact of floodwaters on the study area, we used 100-year flood zone data from the Federal Emergency Management Agency (FEMA) along with road network layers to evaluate the effect of flooding on properties. The Closest Facility function was employed, with pharmacy locations as the facilities, building footprints as the incidents, and flood zone layer as polygon barriers. With the analysis outcome, we categorized the impact conditions into four categories: not affected, detoured, blocked, and inundated (Fig 4).

Fig 4. A map illustrating the impact of floodwater on patients’ vehicular transportation to their nearest pharmacy.

Fig 4

After computing and compiling the three criteria for each building footprint, we calculated the vulnerability index, as summarized in Table 4. Equal intervals were used to assign values ranging from 1 to 5 for the percentage of the population aged 60 and older, as well as travel time in minutes. For floodwater interruption, values were assigned from 1 to 4 based on the level of interruption. We created two separate vulnerability index calculations: [1] one considering the percentage of the population aged 60 and older and personal vehicle travel time, referred to as VAT, and [2] another incorporating the percentage of the 60 + age group, travel time, and floodwater interruption, referred to as VATF. This dual approach distinguishes between baseline vulnerability under current conditions (VAT) and the added impact of potential flooding (VATF), which highlight everyday travel challenges versus those heightened by flood events, respectively. Although the probability of a 100-year flood is 1% annually, this risk may increase due to climate change-induced sea-level rise [62].

Table 4. Scoring criteria for patient vulnerability calculation.

Percentage of population age 60+ Assigned value Personal vehicle travel time (Round Trip, Minutes) Assigned value Flood interruption condition Assigned value
≤ 20% 1 ≤ 10 mins 1 Not affected 1
21–40% 2 11–20 mins 2 Detoured by floodwater 2
41–60% 3 21–30 mins 3 Blocked by floodwater 3
61–80% 4 31–40 mins 4 Inundated by floodwater 4
> 80% 5 > 40 mins 5

For both VAT and VATF, higher values indicate greater vulnerability: VAT ranges from 2 to 10, while VATF ranges from 3 to 14. After computing both indices, we performed a Getis-Ord Gi* analysis [63] using the Hot Spot Analysis tool to determine if the spatial distribution of high and low vulnerability showed statistically significant concentrations. The Gi* was calculated as Eq 2:

Gi*=j=1nwi,jxjXj=1nwi,jS[nj=1nwi,j2(j=1nwi,j)2]n1 (2)

In this equation:

  • xj represents the vulnerability index value for building footprint j, capturing its relative vulnerability based on the VAT or VATF index.

  • wi,j is the spatial weight between building footprints i and j, indicating the degree of spatial proximity between the two locations, as defined by the spatial weights matrix.

  • n is the total number of building footprints included in the analysis.

X•is the mean vulnerability index value for all building footprints in the study area, calculated using Eq. (3).

  • S is the standard deviation of the vulnerability index values across all building footprints, calculated using Eq. (4).

X=j=1nxjn (3)

This equation computes the mean vulnerability index by summing the vulnerability values of all building footprints and dividing by the total number of building footprints n.

S=j=1nxj2n(X)2 (4)

This equation calculates the standard deviation by measuring the dispersion of vulnerability index values around the mean, providing a basis for standardizing the statistic in Eq. (2).

The outcome Gi* were treated as z-scores to determine statistically significant clusters of lower (cold spots) and higher (hot spots) vulnerability. For the search distance, we used the average distance between 30 neighboring building footprints, which was 345 meters.

Finally, since drone delivery is a nascent technology, patients may not fully embrace the service [30,64]. Prioritizing stations that serve the most vulnerable patients can be particularly beneficial when resources are limited. To prioritize drone stations, we calculated the Euclidean distance from each building footprint to the nearest drone station to better understand how vulnerability indices are distributed in relation to each station. By examining these outcomes, we can assess the proximity of high-vulnerability areas to drone stations and determine which stations should be prioritized for resource allocation and response efforts.

3. Results

3.1 Travel time zone and served population

Fig 5 maps the delineated travel time zones across the ES, emphasizing the magnitude of time savings possible with drone delivery as compared with vehicular pharmacy trips. The travel time zones for personal vehicles follow the existing road network patterns (Fig 5a), whereas the drone travel time zones expand in near-perfect circles radiating from each drone station (Fig 5b). As shown Fig 5a, patients in some remote communities face round-trip travel times of up to 50 minutes to reach the nearest pharmacy, often requiring navigation of rural roads that can be further affected by flooding or other access challenges. In contrast, Fig 5b demonstrates that more than 80% of patients on the ES can receive their medications via drone within 10 minutes, underscoring the efficiency and potential reach of this delivery method. Beyond reducing travel time, drone delivery provides a critical alternative for patients who lack reliable vehicular transportation or who face mobility or accessibility limitations. For instance, residents of Tangier Island currently rely on boats or planes for medication deliveries due to the absence of vehicle access to pharmacies. Establishing a drone hub on the island eliminates these barriers, enabling patients to receive medications safely and reliably in less than 10 minutes. However, due to no-fly zone restrictions, a portion of patients in the northeastern ES are not reachable by drone delivery services.

Fig 5. Delineated travel time zones for round-trip personal vehicle driving (a) and one-way drone delivery (b) based on network analysis and Euclidean distance calculations.

Fig 5

Using the population estimation tool outlined in Section 2, it is possible to quantify the benefits of drone delivery specific to older patients who are likely more vulnerable. As shown in Fig 6, over 82% of the total population and those aged 60 + can be reached by one-way drone delivery within 10 minutes, whereas less than 38% of the ES population can complete a round trip drive to a nearby pharmacy within the same time frame. Following the 10-minute travel zone, 31%, 24%, 7%, and 1% of the total population would require 20, 30, 40, and 50 minutes, respectively, to reach the nearest pharmacy by personal vehicle, while 13% and 4% of the population can be served by drones within 20 and 30 minutes. The results for the population aged 60 and older followed a similar pattern, with differences of up to 3%. Overall, more than 99% of patients can be reached by drone within 30 minutes, whereas approximately 10% of those aged 60 and older would need over 30 minutes of driving time to access the nearest pharmacy. Note that residents of Tangier Island (438 individuals, including 180 aged 60 and older), were excluded from personal vehicle travel calculations because they are unable to drive to any pharmacies.

Fig 6. Estimated total population (a) and population aged 60 and older (b) within travel time zones for round-trip personal vehicle travel to nearby pharmacies and one-way drone delivery.

Fig 6

3.2 Patient vulnerability indices

A spatial analysis of the vulnerability indices introduced in Section 2.5 reveals distinct patterns of concentration and distribution across the ES, highlighting disparities between VAT and VATF outcomes. Fig 7 illustrates hot and cold spots identified by the two vulnerability indices, which measure patient vulnerability based on age, travel time, and flood exposure. Blue points indicate clusters of lower vulnerability values at the 99% confidence level, while red points represent clusters of higher vulnerability, highlighting locations where patients face greater challenges accessing pharmacies. The Gi*analysis for VAT (Fig 7a), which considers only the percentage of the population aged 60 and older and travel times, shows greater spatial heterogeneity compared to the VATF results (Fig 7b). In contrast, the VATF results display less varied spatial patterns of hot and cold spots, largely influenced by relative elevation. The VATF outcome highlights a higher concentration of hot spots along the western coast of the ES, driven by elevated vulnerability values assigned to low-lying, flood-prone areas. Cold spots, corresponding to areas of lower vulnerability, are mainly located in the central part of the ES along U.S. Route 13 (Fig 1b), where elevation is comparatively higher.

Fig 7. Results of Getis-Ord 𝐆i* spatial distribution analysis for the two vulnerability indices: (a) VAT and (b) VATF, with blue indicating low (cold spots) and red indicating high (hot spots) vulnerability clusters.

Fig 7

The difference between the VAT and VATF outcomes is particularly pronounced in the Chincoteague Island area in the northeast. Under the VAT results, lower vulnerability values are concentrated near the island’s pharmacy, with higher values observed among patients located farther away, particularly in areas with a higher proportion of older residents. In contrast, the VATF analysis indicates that most of the island exhibits elevated vulnerability, driven by its low-lying, flood-prone terrain. Only a few localized areas with relatively higher elevation and a smaller percentage of residents aged 60 and older show lower VATF values.

The spatial distribution of VAT and VATF indices varies notably among the four nearest drone automation stations, underscoring differences in service reach and vulnerability patterns across the ES. For clarity, the stations are numbered 1–4 from north to south in Table 5. The two northern stations cover a broader service area, reaching a greater number of residences, while the southern stations, particularly Station 4, serve fewer patients due to a lower density of residences within their flight range (Table 5). Station 1 exhibits the highest mean values for both VAT and VATF indices, indicating that it serves a population with greater baseline vulnerability as well as heightened vulnerability under flood conditions. For the VAT index, Stations 1 and 3 stand out with higher mean values (4.64 and 4.50); however, Station 3 displays a wider interquartile range and a larger number of high-scoring patients, suggesting greater variability in vulnerability levels (Fig 8). For the VATF index, Station 1 not only has the highest mean and median values but also a wider interquartile range, reflecting the compounding effects of flood risk in its service area. In contrast, Station 4, the southernmost station, serves the smallest population base and shows the lowest mean values for both indices, indicating that patients in its coverage area are comparatively less vulnerable under both baseline and flood-affected scenarios.

Table 5. Number of building footprints, along with the mean and standard deviation of VAT and VATF indices, calculated for each nearest drone automation station. Note that building footprints within no-fly zones were excluded from this analysis.

Drone Automation Station Building Footprint Count VAT
(value range: 2–10)
VATF
(value range: 3–14)
Mean Standard deviation Mean Standard deviation
1. Riverside Shore Medical Center at Metompkin 5883 4.64 1.43 6.61 2.30
2. Riverside Shore Memorial Hospital 6211 4.31 1.44 5.99 2.25
3. Riverside Eastern Shore Family Medicine 5045 4.50 1.71 5.89 2.09
4. Riverside Cape Charles Medical Center 3232 4.34 1.36 5.41 1.48

Fig 8. Violin plots of VAT and VATF indices for drone stations arranged from north to south.

Fig 8

White bars represent median values, with thicker lines indicating the interquartile range. The plots show the kernel density estimation boundaries, where wider curves correspond to higher numbers of patients.

4. Discussion

4.1 Drone delivery efficiency and healthcare vulnerability hot spots

Our findings demonstrate that drone-based medical delivery significantly reduces travel time for rural residents on the ES, with the greatest benefits for vulnerable populations. While personal vehicle trips to pharmacies can take up to 50 minutes, over 80% of ES patients can receive drone deliveries within 10 minutes, including those on Tangier Island, where traditional transportation is unavailable. Spatial analysis of vulnerability indices reveals concentrated high-risk areas along the western coast, influenced by low elevation and flood susceptibility. Drone service reach varies across automation stations, with northern stations covering more patients and higher vulnerability scores. These findings highlight the potential of drones to enhance equitable healthcare access in flood-prone rural communities.

The travel zone analysis demonstrates that drone delivery provides significantly faster service than patient travel by personal vehicle, especially for residents of remote or waterfront communities (Fig 5). Unlike ground transportation, drones fly directly to their destinations at consistent speeds, avoiding traffic delays and road speed limits. With the exception of the Chincoteague area, where delivery may take up to 30 minutes due to no-fly zone restrictions, the majority of the ES can be reached by drone within 20 minutes. In contrast, only two pharmacies are located in two populated coastal towns (i.e., Chincoteague and Cape Charles), while the remaining five are concentrated along the main corridor of the ES (Fig 2b). As a result, patients in outlying areas must drive longer distances using slower secondary or tertiary roads, often requiring 40–50 minutes to reach a pharmacy by personal vehicle.

Along the ES, drones have the potential to significantly improve medication delivery times, particularly for older adults and residents of remote areas. Within 10 minutes, drones can reach over 80% of both the total population and those aged 60 and older. In contrast, fewer than 40% of either group can access a pharmacy within the same timeframe using round-trip personal vehicle travel (Fig 6). While overall travel times by car are comparable between age groups, a slightly higher proportion of the older population (~10%) falls within zones requiring more than 40 minutes of round-trip travel, compared to ~8% of the total population. This suggests that older adults are somewhat more concentrated in remote areas with limited access to nearby pharmacies. These individuals would particularly benefit from drone delivery services, which can offer substantially reduced travel times.

On Tangier Island, where land subsidence and erosion pose significant threats to the community [65], drone delivery may also be transformative. With a population of 438, of which approximately 41% (180 individuals) are aged 60 and older, Tangier Island has only one grocery store and no pharmacy. Currently, most medical services are provided by a single healthcare center, with supplies delivered by a single-engine light airplane [66,67]. While emergency medical support is available via helicopter from the Maryland State Police [66], establishing a drone delivery service and on-site drone station could substantially enhance medical supply access for this remote community.

The hot spot analysis of the VAT and VATF indices highlights the critical roles of travel time, elevation, and flood risk in determining service effectiveness. While the overall hot spot patterns for both VAT and VATF are similar, the VAT index, which accounts only for age and travel time, shows that older patients with longer travel distances face heightened vulnerability. In contrast, the VATF analysis more distinctly highlights concentrated areas of high vulnerability in remote, waterfront communities, primarily due to their low-lying elevations (Fig 7). This pattern is particularly evident along the western coast of the Eastern Shore, where a series of isolated communities are accessible only by secondary roads extending toward the Chesapeake Bay (Fig 1). Notably, although both Cape Charles and Chincoteague are waterfront communities with pharmacies, only Chincoteague exhibits VATF hot spots. This distinction is explained by Chincoteague’s lower elevation, where 75% of building footprints are inundated during a 100-year flood event, significantly limiting access to its local pharmacy.

In the context of service prioritization, spatial analysis using the VAT and VATF indices suggests that Station 1 in the northern ES should be prioritized for drone-based medication delivery. Under the VAT index, which considers age and travel time, Stations 1 and 3 show higher mean vulnerability scores, indicating their importance in serving older patients with limited access. However, when flood risk is incorporated into the VATF index, Station 1 emerges as the most critical hub, with the highest mean VATF score and the largest number of patients within its coverage area (Table 5 & Fig 8). This is largely due to its geographic distance from existing pharmacies—most other stations are located near pharmacies, leading to reduced vulnerability in their surrounding areas. Additionally, Station 1 covers the remote Chincoteague area, where a combination of physical isolation, limited infrastructure, and flood susceptibility exacerbates access challenges. These findings underscore the need to account for geographic complexity and environmental risk in the strategic planning of drone station placement, particularly in rural and flood-prone regions.

4.2 Scalable applications and policy implications

The geospatial analysis framework developed in this study is designed to be scalable and generalizable to other regions. By relying exclusively on publicly available datasets from federal, state, and county sources (Table 2), the methodology protects patient privacy while ensuring broad applicability. Although parcel data was obtained locally to target residential land use, most other datasets, such as road networks, building footprints, and elevation, are widely accessible across the U.S. This allows for straightforward replication in other medically underserved or flood-prone communities, making the approach a flexible and resource-efficient tool for planning drone-based healthcare delivery in diverse rural settings.

While some indices have been proposed for identifying health risks at a national level, such as Social Vulnerability Index used by the CDC and the Agency for Toxic Substances and Disease Registry (ATSDR) [6870], the indices developed in this study operate at a finer, individual level, offering a more precise tool for evaluating delivery strategies. This approach can be adapted to other rural areas in Virginia or regions with similar geospatial data availability. By replicating this process, local and regional authorities can more effectively identify vulnerable hot spots, optimize healthcare resource allocation, and support the long-term viability of rural communities.

This study demonstrates feasible and scalable benefits of drone delivery systems in rural environments. As discussed in Section 2.3, future technological and regulatory developments may permit extended drone flying hours and operations in a broader range of weather conditions [58]. To engage the community and foster education, Riverside Health surveyed ES residents about their perceptions and experiences with drone delivery both before and after the medical delivery project, fostering awareness and support. Additionally, several residents were hired and trained by DroneUp as drone operators and operations personnel, promoting economic engagement and local expertise [58]. Employing and training residents as drone operators fosters economic opportunities and community engagement, enhancing program sustainability. This scalable model offers a transformative approach to improving healthcare access and resilience in underserved communities.

4.3 Study limitations and future directions

While our analysis provides valuable insights, several limitations persist. Regarding the comparison of travel times of drones and personal vehicles. In constructing the network dataset for travel time calculations, road hierarchy and speed limits were considered. Additional factors, such as restrictions on turns, variable traffic conditions [71], and speed enforcement [72], could enhance the precision of these estimates. Previous research has also indicated that drivers often exceed posted speed limits [73,74], with speed preferences influenced by factors such as age, normlessness scale, and self-assessed driving skills [75]. Moreover, the drone travel times were computed using a fixed flight speed and station locations. Future research could investigate more sophisticated drone delivery systems, such as models that utilize multiple drone sizes with varying speed limits (e.g., Raj and Murray [76]), networks that allow drone exchanges between stations (e.g., Cokyasar, Dong [77]), or the inclusion of loading times from suppliers to drone stations. Additionally, recent advancements in AI-enabled drone logistics have demonstrated the potential of intelligent routing and operational optimization to enhance delivery efficiency and scalability [78]. Incorporating such AI-driven approaches in future analyses could allow for dynamic route planning, adaptive scheduling, and optimized resource allocation, further strengthening the resilience and responsiveness of drone-based healthcare delivery systems in flood-prone rural regions.

While our analysis used fixed drone speeds and station locations to estimate delivery times, actual flight performance provides critical validation and operational context. In parallel with our modeling efforts, DroneUp conducted extensive test flights to assess the feasibility of drone-based medical deliveries on ES (Fig 2). A total of 352 actual and 93 simulated flights were completed using the Prism Sky (Fig 2b) and the Swoop Aero Kite. The Prism Sky averaged a delivery time of 5.1 minutes for distances between 1.8 and 2.5 miles, while the Swoop Aero Kite completed a 36.4-mile delivery in approximately 15 minutes. These tests help ground-truth assumptions about drone capabilities and delivery timing. To further support operational planning, an airspace awareness and routing analysis was conducted using historical flight track data to identify preferred corridors and avoid potential conflicts. Three patients prescribed antihypertensive medications participated in the drone delivery pilot and provided positive feedback. Additionally, a 15-mile test flight from Riverside Shore Memorial Hospital to Tangier Island demonstrated the feasibility of longer-range missions [79].

Another limitation is the presence of no-fly zones, in which 7,749 individuals, including 2,943 aged 60 and older, are unserved (Fig 7). Moreover, approximately 4% of the total population and 5% of the 60-plus population on the ES, specifically in Chincoteague, still require over 20 minutes for drone delivery due to longer distances and the need to navigate around no-fly zones. A viable alternative for these areas could be truck-based drone delivery (e.g., Yoo and Chankov [80], Yin, Li [81]). Future research could also explore comparative analyses between bulk vehicle delivery and drone delivery in rural settings (e.g., Chiang, Li [82], Kirschstein [83] to assess relative efficiency and cost-effectiveness. For example, Kirschstein [83] examined the energy demands of diesel trucks, electric trucks, and drones, finding that while electric trucks generally consume the least energy, drones are particularly competitive in rural contexts. Such comparisons could support the development of more sustainable and equitable delivery strategies to address healthcare access disparities in rural communities.

The scoring methodology used for VAT and VATF computation may underestimate the complexity of patient vulnerability. In this study, we employed an equal interval scoring system for the percentage of the population aged 60 and older, as well as for travel time, with assigned values ranging from 1 to 5. Additionally, flood interruption conditions were classified into four levels, corresponding to values from 1 to 4 (Table 4). However, this approach may oversimplify patient vulnerability. For instance, Ostchega, Fryar [55] reported hypertension prevalence rates of 22.4%, 54.5%, and 74.5% among adults aged 18–39, 40–59, and 60 and older, respectively, with notable variations by gender. Integrating these prevalence rates into the vulnerability calculation could enhance its accuracy. Moreover, the relationship between age and driving behavior is nuanced. While willingness to drive generally decreases with age and varies by gender [84,85], driving ability remains crucial for successful aging, as it is linked to independence and social interaction [86,87]. This underscores the need for a more sophisticated approach to vulnerability computation that accounts for health conditions and behavioral factors.

Flooding risk in this work was captured by the relatively low probability of a 100-year flood event, but chronic high-tide flooding presents a more urgent threat to coastal communities. For example, Hino, Belanger [88] examined the impact of high-tide flooding in Annapolis, Maryland, and found that visits to the historic downtown area decreased by 1.7%, resulting in local economic losses. According to National Oceanic and Atmospheric Administration [89], the tidal station in Wachapreague (Fig 1b), located on the middle east of ES, predicts up to 17 days of high-tide flooding annually. With ongoing sea-level rise driven by climate change, the ES is expected to face even more severe flooding impacts in the future [42,90]. By 2050, high-tide flooding could occur on up to 65 days per year in Wachapreague [89].

Incorporating community-specific preferences and critical thresholds into vulnerability assessments can significantly enhance the effectiveness of drone-based healthcare delivery strategies. Future research may consider conducting a comprehensive community survey to identify key factors influencing patient preferences (e.g., Kim [64], Bafouni-Kotta, Villanueva [91]). For instance, Kimmel, Bono [92] utilized Medicaid claims data to explore the relationship between drive time and retention rates in HIV care. Their findings indicated that a 30-minute drive time significantly impacts retention in rural areas, while no such relationship was observed in urban settings. Identifying similar thresholds in rural healthcare access and incorporating these insights into vulnerability index computation could provide valuable guidance for strategic planning in drone-based service deployment. In addition, assessing human-drone interaction within local communities would be essential to understanding user perspectives, such as concerns about security, usability, and perceived usefulness, which could further refine and improve the implementation of drone services [93].

The geospatial dataset compiled in this study can also serve as a baseline for further analysis, including cost-benefit assessments of drone-based medicine delivery. The proposed methodology may aid stakeholders in rural communities in mobilizing healthcare resources to patients, rather than requiring patients to travel for healthcare services or medications [94]. For example, Haidari, Brown [31] found that drones saved approximately $0.08 per vaccine dose compared to land-based transportation in Mozambique. One rural community in British Columbia, Canada has used medical deliveries via drones to help support healthcare providers who might otherwise feel isolated and overburdened, and therefore more prone to leave [94]. Another community in rural West Texas has envisaged reducing the number of vehicle trips to transport supplies to rural clinics, especially since those transporting the supplies are often licensed medical professionals who might otherwise have spent time in the service of patients [95]. By combining these data-driven insights with local community needs, drone service providers may partner with healthcare organizations to transform the delivery of essential medical services, especially in remote, flood-prone areas. This would not only improve operational efficiency but also ensure timely access to critical healthcare, reducing the vulnerability of underserved rural populations.

5. Conclusion

This study evaluated the effectiveness of drone-based medication delivery in improving healthcare access for vulnerable rural populations, particularly aging residents in flood-prone coastal areas. Using the ES of Virginia as a case study, this study assessed healthcare accessibility in flood-prone coastal communities by comparing traditional vehicle-based pharmaceutical trips with drone-based deliveries, while also evaluating patient vulnerability. Travel times for personal vehicles were calculated using a hierarchical road network and round-trip travel assumptions, whereas drone delivery times were estimated using direct flight paths from drone stations. Population layers were then aggregated within travel zones to quantify access efficiency. To identify the most at-risk populations, two vulnerability indices were developed: VAT, incorporating patient age and vehicle travel time, and VATF, additionally accounting for floodwater interruptions. Hot spot analysis identified statistically significant clusters of high vulnerability, guiding the prioritization of drone stations for service deployment. Overall, this integrated approach demonstrated how drones can improve timely access to medications, particularly for the most vulnerable populations, and provided a scalable framework for optimizing resource allocation under both everyday and flood-impacted conditions.

The three main contributions of this study include: first, quantifying the substantial time savings of drone-based medication delivery compared to traditional vehicle travel; second, developing two spatial vulnerability indices that integrate demographic, geographic, and flood exposure data to identify and prioritize high-need patients; and third, evaluating drone hub performance and geographic reach under varying vulnerability profiles to guide effective placement and resource allocation. Together, these contributions demonstrate that drone delivery networks are not only feasible but also strategically valuable, providing a more equitable and resilient alternative to vehicle-dependent healthcare access. This approach helps improve healthcare access by identifying high-need populations, optimizing drone hub placement, and providing a scalable framework for resilient, equitable medication delivery in underserved communities.

Future research may enhance travel time estimates by incorporating real-world driving behaviors, dynamic traffic conditions, and more flexible drone routing systems, including multi-drone networks, station exchanges, and variable drone speeds. The vulnerability scoring methodology may be improved by integrating health condition prevalence, behavioral factors, and community-specific thresholds could provide a more accurate assessment of patient needs. Additionally, future research may address service gaps in no-fly zones through alternatives like truck-based drone delivery, conducting community surveys, and assessing human-drone interactions are also recommended. Finally, the geospatial dataset developed here offers a valuable foundation for cost-benefit analyses and stakeholder collaboration to expand efficient, adaptive, and community-informed drone-based healthcare delivery in rural, flood-prone regions.

In summary, this study investigates the transformative potential of drone technology in enhancing healthcare access for vulnerable aging populations in rural, flood-prone areas. By integrating publicly available data to identify at-risk communities, the proposed tools not only address immediate healthcare delivery challenges but also contribute to broader public health initiatives. This innovative approach can serve as a model for other underserved regions, promoting resilience in healthcare systems and ensuring equitable access to essential services, ultimately improving health outcomes for marginalized populations.

Acknowledgments

We appreciate the feedback and support provided by members of Riverside Health, DroneUp, Accomack Northampton Planning District Commission, Virginia Innovation Partnership Corporation, and Virginia Institute for Space Flight & Autonomy. We would also like to acknowledge Nathan Lam for his support and the reviewers and editors who improved our manuscript.

Data Availability

All the geospatial outcomes are available from the Harvard Dataverse (webpage: https://dataverse.harvard.edu/dataverse/DroneDOTSMART).

Funding Statement

Y.-H.C, A.M., K.O., T.W., and H.R. received financial support from the United States Department of Transportation’s Strengthening Mobility and Revolutionizing Transportation (SMART) program. The grant number is 69A3552341006-SMARTFY22N1P1G54. The funder did not play any role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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Decision Letter 0

Zeashan Hameed Khan

21 May 2025

PONE-D-25-20755Drone-Based Medication Delivery for Flood-Prone Coastal Communities: Optimizing Access and EquityPLOS ONE

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Reviewer #2: Partly

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Reviewer #1: No

Reviewer #2: No

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Reviewer #2: Yes

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Reviewer #1: This paper addresses the feasibility of using drone delivery for medicine compared to road transportation methods. The authors mostly emphasize on the reduced time as the most benefecial aspect.

During emergency situations, the reduced time is a crucial factor, but for general deliveries, maybe the role of reduced time is over emphasized. I think the study should have considered other crucial factors to make a solid case. Here are my observations:

1. Though delivery time is reduced for a single delivery in drones, traditional vehicles can deliver in bulk and can complete multiple deliveries at neighbouring region within a very short time thus significantly reducing overall time/delivery. Without accounting for this the comparison seems unfair. Other minor thing could be time to load from pharmacy to drone site shipment or similar issues.

2. There is no ballpark cost estimates/comparisons per delivery between the methods in the paper. While one driver can possibly deliver to many people in a day, a drone pilot might not be able to reach much people due to one shipment/flight requiring more skilled pilots. Other aspects like battery costs/replacement costs could challenge the financial feasibility as well. At least a rough estimate of costs/delivery would be helpful.

3. This report is based on a particular location. How generalizable is this study to other places? Some discussions would be helpful.

I appreciate the authors for addressing a problem which might benefit several people get access to healthcare. I would appreciate more if case for drone based delivery is more convincing.

Reviewer #2: 1. The abstract lacks quantitative evidence on how much drone delivery improves accessibility or reduces delays compared to traditional methods, which weakens the impact of its findings.

2. The proposed vulnerability indices are mentioned, but the abstract does not explain how they were validated or their effectiveness in prioritizing patients, leaving their practical utility unclear.

3. The introduction should clearly conclude with a distinct paragraph that highlights the novel contributions of your work.

4. The literature review should benefit from more explorations of previous studies.

5. The discussion section needs to be expanded to more thoroughly analyze the results.

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7. The second paragraph of the conclusion should provide clear and actionable future recommendations.

8. Some equations are not properly cited.

9. Please place the figures within the text for the next round of revision.

**********

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Reviewer #1: No

Reviewer #2: Yes:  Luttfi A. Al-Haddad

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PLoS One. 2025 Oct 6;20(10):e0333696. doi: 10.1371/journal.pone.0333696.r002

Author response to Decision Letter 1


31 Jul 2025

Reviewer #1:

1. This paper addresses the feasibility of using drone delivery for medicine compared to road transportation methods. The authors mostly emphasize on the reduced time as the most beneficial aspect.

Response: Thank you for your comment. We agree that reduced travel time is a key advantage of drone delivery over personal vehicle travel, and this was a primary focus of our GIS-based analysis. In the discussion section (4.1), we also expanded on additional benefits, particularly for elderly residents and their caregivers—highlighting the convenience of avoiding long, often burdensome trips from remote areas to pharmacies typically located in larger, more centralized communities along major roads.

2. During emergency situations, the reduced time is a crucial factor, but for general deliveries, maybe the role of reduced time is over emphasized. I think the study should have considered other crucial factors to make a solid case. Here are my observations:

Response: We have revised the manuscript accordingly. Please see our detailed responses below.

3. Though delivery time is reduced for a single delivery in drones, traditional vehicles can deliver in bulk and can complete multiple deliveries at neighboring region within a very short time thus significantly reducing overall time/delivery. Without accounting for this the comparison seems unfair. Other minor thing could be time to load from pharmacy to drone site shipment or similar issues.

Response: We agree that bulk deliveries via traditional vehicles can be an effective service model for rural communities. Bulk deliveries, however, may not serve all customers on the Eastern Shore. For example, residents of Tangier Island (included in the study area) are not connected to the mainland by any bridge or tunnel. Therefore, the only delivery methods currently available in that area are ferries and small airplanes. Our current analysis focuses on individual patients using personal vehicles to retrieve their prescriptions, rather than on pharmacy-led bulk delivery. As such, we did not include a direct comparison between bulk vehicle delivery and drone delivery.

To clarify this scope, we have revised the manuscript by specifying “personal vehicle travel” throughout the text. Additionally, we have added a new paragraph in the Introduction section highlighting the importance of personal vehicle use in rural areas, particularly for healthcare access. We believe these revisions help better define the study’s focus and provide readers with appropriate context for interpreting our findings. Please refer to: “Personal vehicles are essential for mobility and access to critical services in rural communities, particularly for older adults. A national study of individuals aged 65–79 found that rural residents were 7% more likely than their urban and suburban peers to emphasize the importance of driving (Strogatz et al., 2019), underscoring their reliance on personal transportation. In rural North Carolina, individuals with a driver's license made 2.29 times more healthcare visits, while those with access to family or friends for transportation had 1.58 times more visits (Arcury et al., 2006), highlighting how transportation directly affects healthcare access. Yet, despite this heavy reliance, older drivers in rural areas face disproportionate barriers due to chronic health conditions, physical impairments, and age-related declines in driving ability (Lyman et al., 2001; Krasniuk & Crizzle, 2023). Without viable transportation alternatives, these challenges severely limit rural seniors' access to care and independence.”

We also added several sentences in Section 4.3, Study Limitations and Future Directions, addressing the comparison between truck-based and drone delivery, as well as the consideration of loading times from suppliers:

“ … or the inclusion of loading times from suppliers to drone stations.”

“Future research could also explore comparative analyses between bulk vehicle delivery and drone delivery in rural settings (e.g., Chiang et al., 2019; Kirschstein, 2020) to assess relative efficiency and cost-effectiveness. For example, Kirschstein (2020) examined the energy demands of diesel trucks, electric trucks, and drones, finding that while electric trucks generally consume the least energy, drones are particularly competitive in rural contexts. Such comparisons could support the development of more sustainable and equitable delivery strategies to address healthcare access disparities in rural communities.”

4. There is no ballpark cost estimates/comparisons per delivery between the methods in the paper. While one driver can possibly deliver to many people in a day, a drone pilot might not be able to reach much people due to one shipment/flight requiring more skilled pilots. Other aspects like battery costs/replacement costs could challenge the financial feasibility as well. At least a rough estimate of costs/delivery would be helpful.

Response: We appreciate the Referee’s suggestion. As noted in a previous response, this study specifically focuses on comparing personal vehicle travel with drone delivery, rather than bulk delivery by truck. We have updated Introduction section, Page 6 to address the concern of delivery cost as follows:

1. As an estimate, a recent consulting report by PricewaterhouseCoopers estimated that the average cost of drone delivery per item was between $6 to $25. The cost is expected to drop to $2 per delivery by 2034 (Gajewska et al., 2024).

2. In the United States, Walmart offers drone delivery at certain locations for $19.99 per order (Walmart, 2024).

3. A drone delivery company called Manna that operates in Ireland has achieved a cost of $4 per order (Bogaisky, 2025).

It is important to note that a single drone pilot is currently permitted to operate three drones at the same time. The pilot observes the three flights remotely. In the future, the FAA may allow a single drone pilot to operate even more drones at the same time to help reduce the cost of deliveries.

5. This report is based on a particular location. How generalizable is this study to other places? Some discussions would be helpful.

Response: We have included a paragraph to address this comment. Please refer to section 4.2: “The geospatial analysis framework developed in this study is designed to be scalable and generalizable to other regions. By relying exclusively on publicly available datasets from federal, state, and county sources (Table 2), the methodology protects patient privacy while ensuring broad applicability. Although parcel data was obtained locally to target residential land use, most other datasets, such as road networks, building footprints, and elevation, are widely accessible across the U.S. This allows for straightforward replication in other medically underserved or flood-prone communities, making the approach a flexible and resource-efficient tool for planning drone-based healthcare delivery in diverse rural settings.”

6. I appreciate the authors for addressing a problem which might benefit several people get access to healthcare. I would appreciate more if case for drone based delivery is more convincing.

Thank you for your thoughtful comment. We agree that making a stronger case for drone-based delivery is essential to highlight its potential in addressing healthcare disparities in rural communities. In response, we have expanded the Introduction section to include additional context on the regulatory approval of drone-based medical delivery, as well as current cost estimates reported by major companies such as Walmart.

Furthermore, in Section 4.3, we have added a detailed paragraph discussing real-world test flights conducted in the study area by DroneUp. This includes over 350 actual and 90 simulated flights, demonstrating the operational feasibility and delivery speed of drones across various distance ranges. We also highlight feedback from patients who participated in the pilot program, which reflects strong community acceptance and the perceived usefulness of drone delivery services.

These additions aim to present a more convincing and evidence-based case for the viability of drone-enabled healthcare access.

Reviewer #2:

7. The abstract lacks quantitative evidence on how much drone delivery improves accessibility or reduces delays compared to traditional methods, which weakens the impact of its findings.

Response: Thank you for your comment, we have revised the description of abstract to include quantitative evidence. Please see the revised abstract: “Compared to traditional vehicle travel, drone delivery reduced trip times from up to 50 minutes to under 10 minutes for more than 80% of the population, including elderly patients.”

8. The proposed vulnerability indices are mentioned, but the abstract does not explain how they were validated or their effectiveness in prioritizing patients, leaving their practical utility unclear.

Response: We have added descriptions of the spatial analysis used to examine the clustering of vulnerable patients and the prioritized station. Please refer to the revised abstract “These indices were examined using Getis-Ord Gi* spatial analysis, which identified statistically significant clusters of high-need patients, particularly around the northernmost drone station. The results reveal that elderly residents in remote, low-lying areas are especially vulnerable to missed prescriptions due to both transportation barriers and flooding.”

9. The introduction should clearly conclude with a distinct paragraph that highlights the novel contributions of your work.

Response: We have revised the second last paragraph of introduction to highlight the novel contributions of our study. Please refer to the Introduction: “Using Virginia’s Eastern Shore (hereafter ES) as a case study, this study makes three key contributions to the field of healthcare accessibility and disaster-resilient delivery systems. First, it quantifies the substantial time savings of drone-based medication delivery over traditional vehicle travel in rural, flood-prone areas, providing one of the first direct comparisons in a non-emergency context. Second, it introduces two spatial vulnerability indices that integrate demographic, geographic, and flood exposure data to identify high-need patients, offering a replicable framework for prioritizing healthcare interventions. Third, it evaluates drone hub performance and reach across varying vulnerability profiles, guiding more effective placement and resource allocation under operational constraints. Together, these contributions demonstrate the feasibility and strategic value of drone delivery networks for enhancing medication access in underserved coastal communities and offer a scalable model for broader implementation in similarly challenged regions worldwide.”

10. The literature review should benefit from more explorations of previous studies.

Response: We have added a new paragraph highlighting the importance of personal vehicles in rural areas and the additional transportation challenges faced by older populations. We also incorporated the work of Tomio et al. (2010) to provide further evidence on how flooding disrupts access to medication, and cited a news article by Popper (2015) that documents the first government-approved medical drone delivery in Virginia. Please refer to the Introduction section.

11. The discussion section needs to be expanded to more thoroughly analyze the results.

Response: We have revised the discussion section to provide a more thorough analysis of the results, as requested. Please refer to Section 4.1 for the updated content. In response to this comment, the word count for this section has been expanded from 552 to 831 words to offer deeper insights into the findings and their implications.

12. The first paragraph of the conclusion should succinctly summarize the contributions of the study in past tense.

Response: We have revised the conclusion to be more succinctly summarize the contribution in past tense. Please refer to the Conclusion section.

13. The second paragraph of the conclusion should provide clear and actionable future recommendations.

Response: We have included a new paragraph to provide clear and actionable future recommendations. Please see second paragraph in Conclusion section: “Future research should enhance travel time estimates by incorporating real-world driving behaviors, dynamic traffic conditions, and more flexible drone routing systems. Improving the vulnerability scoring methodology by integrating health condition prevalence, behavioral factors, and community-specific thresholds could offer a more accurate assessment of patient needs. Addressing service gaps in no-fly zones through alternatives like truck-based drone delivery and conducting community surveys to guide strategic planning are also recommended. Finally, the geospatial dataset developed here provides a valuable foundation for future cost-benefit analyses and stakeholder collaboration to expand drone-based healthcare delivery in rural, flood-prone regions.”

14. Some equations are not properly cited.

Response: We have revised the relevant sections to ensure that all equations are properly cited.

15. Please place the figures within the text for the next round of revision.

Response: We have inserted figures within the text.

Attachment

Submitted filename: Response to Reviewer_medical delivery in ES June 30.docx

pone.0333696.s002.docx (32.6KB, docx)

Decision Letter 1

Zeashan Hameed Khan

18 Aug 2025

PONE-D-25-20755R1Drone-Based Medication Delivery for Flood-Prone Coastal CommunitiesPLOS ONE

Dear Dr. Chen,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

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We look forward to receiving your revised manuscript.

Kind regards,

Zeashan Hameed Khan, Ph.D.

Academic Editor

PLOS ONE

Journal Requirements:

If the reviewer comments include a recommendation to cite specific previously published works, please review and evaluate these publications to determine whether they are relevant and should be cited. There is no requirement to cite these works unless the editor has indicated otherwise. 

Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

Additional Editor Comments:

The revised version has significantly improved but still needs some minor corrections.

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #2: (No Response)

Reviewer #3: (No Response)

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #2: (No Response)

Reviewer #3: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #2: (No Response)

Reviewer #3: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #2: (No Response)

Reviewer #3: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #2: (No Response)

Reviewer #3: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #2: Minor English proofreading is required, please look for typos as they do exist within the manuscript.

Reviewer #3: Paper Review and Comments

1. Title and Abstract

• Title: Drone-Based Medication Delivery for Flood-Prone Coastal Communities

• Abstract:

Access to healthcare remains a critical challenge for rural populations, particularly in flood-prone coastal communities where transportation barriers limit access to essential medical services. This study evaluates the effectiveness of drone-based medication delivery in improving healthcare accessibility for vulnerable populations on Virginia’s Eastern Shore. Compared to traditional personal vehicle travel, drone delivery reduced trip times from up to 50 minutes to under 10 minutes for more than 80% of the population, including elderly patients. Using publicly available datasets, we developed two transportation vulnerability indices that incorporate age, travel time, and flood risk to prioritize patients for drone-based pharmaceutical delivery. These indices were examined using Getis-Ord Gi* spatial analysis, which identified statistically significant clusters of high-need patients, particularly around the northernmost drone station. The results reveal that elderly residents in remote, low-lying areas are especially vulnerable to missed prescriptions due to both transportation barriers and flooding. Our approach demonstrates how drone delivery can reduce healthcare access disparities while offering a scalable and resilient framework for other medically underserved regions, especially under time or resource constraints.

2. Introduction

• Aim and Motivation:

o Aim and Motivation is stated in introduction part.

o However, it should be explained little more.

o More references and explanation should be added in introduction as the introduction is very less.

• Research Questions and Objectives:

o The research objectives are not mentioned in the paper, please mention the objectives of the paper.

• Literature Review:

o Some more related papers can be included in the related work section.

3. Methodology

• Clarity of Methods:

o The methods are stated clearly that is good.

• Innovativeness:

o The proposed approach is novel.

4. Results and Analysis

• Presentation of Data:

o Presentation of the data is good.

o Some more details and references can be added in the introduction areas.

o More details can be added in the other sections like methodology and conclusion sections.

• Analysis and Discussion:

o The results are well analyzed.

5. Conclusion and Contributions

• Summary of Findings:

o The conclusion and future scope are stated good.

o But state what innovative method can be used in the future.

o State how your approach can help in the relevant field?

• Contributions:

o The contributions to the field are stated nicely.

o Some more details can be added in the conclusion part.

6. Language and Writing Style

• Grammar and Clarity:

o Some very little mistakes in grammar, that can be revised.

7. References

• Relevance and Recency:

o The references are relevant.

o However the references provided are very less, some more references can added. I have also recommended some references you can add them and extend the referencing area.

• Formatting:

o References are in proper order.

o However some more related references can be added, some references are given below in the recommendations section.

8. Figures, Tables, and Equations

• Figures:

o The figures should be explain in more details inside the text.

• Tables:

o The tables should be explain in more details inside the text.

• Equations:

o Explain each parameter of the equation/algorithm.

9. Recommendations for Improvement

1. The introduction section can be furnished with some new papers like:.

a. https://doi.org/10.4108/airo.5855

b. Using the different AI methods : https://doi.org/10.1007/978-981-97-5979-8_8 , https://doi.org/10.1007/978-981-97-5979-8_7

other food deliravy robot: doi: 10.1109/ACCESS.2024.3355278.

c.

10. Please answer below question

How did drone delivery compare to traditional personal vehicle travel times for medication delivery in Virginia’s Eastern Shore?

What factors were incorporated into the transportation vulnerability indices developed in this study?

Which area was identified as having the highest concentration of vulnerable patients, and why?

What role did community engagement and collaboration with multiple organizations play in the project’s success?

What future improvements to the vulnerability scoring methodology and service delivery were recommended by the study?

Overall Evaluation

• Final Recommendation:

• paper format and presentation should modify based on template.

• Major Revisions.

**********

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Reviewer #2: Yes:  Luttfi A. Al-Haddad

Reviewer #3: No

**********

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PLoS One. 2025 Oct 6;20(10):e0333696. doi: 10.1371/journal.pone.0333696.r004

Author response to Decision Letter 2


4 Sep 2025

Response to Reviewers

Reviewer #2:

1. Minor English proofreading is required, please look for typos as they do exist within the manuscript.

Response: Thank you for your comment. We have reviewed the manuscript and corrected identified typos; please refer to the tracked changes document for details.

Reviewer #3:

2. Title and Abstract

• Title: Drone-Based Medication Delivery for Flood-Prone Coastal Communities

• Abstract:

Access to healthcare remains a critical challenge for rural populations, particularly in flood-prone coastal communities where transportation barriers limit access to essential medical services. This study evaluates the effectiveness of drone-based medication delivery in improving healthcare accessibility for vulnerable populations on Virginia’s Eastern Shore. Compared to traditional personal vehicle travel, drone delivery reduced trip times from up to 50 minutes to under 10 minutes for more than 80% of the population, including elderly patients. Using publicly available datasets, we developed two transportation vulnerability indices that incorporate age, travel time, and flood risk to prioritize patients for drone-based pharmaceutical delivery. These indices were examined using Getis-Ord Gi* spatial analysis, which identified statistically significant clusters of high-need patients, particularly around the northernmost drone station. The results reveal that elderly residents in remote, low-lying areas are especially vulnerable to missed prescriptions due to both transportation barriers and flooding. Our approach demonstrates how drone delivery can reduce healthcare access disparities while offering a scalable and resilient framework for other medically underserved regions, especially under time or resource constraints.

Introduction

• Aim and Motivation:

o Aim and Motivation is stated in introduction part.

o However, it should be explained little more.

o More references and explanation should be added in introduction as the introduction is very less.

Response: We appreciate the reviewer’s comment. While the original introduction was intentionally concise to maintain focus, we have expanded it by adding 11 additional references and contextual details to strengthen the background and motivation for our study. Because the reviewer did not specify the missing literature, we incorporated studies across multiple dimensions to enrich the introduction, including:

• Literature supporting research motivation

o Casey et al. (2002): financial constraints affecting rural pharmacy services

o Berenbrok et al. (2022); Law et al. (2013); Todd et al. (2015); Sharareh et al. (2024): disparities in access to pharmaceutical services between urban and rural communities

o Tharumia Jagadeesan & Wirtz (2021): review of studies on pharmacy accessibility

o Ranković Plazinić & Jović (2018): mobility limitations of elderly populations

o Wassmer et al. (2025): impact of flooding on healthcare accessibility

• Literature on medical delivery using drones

o Snouffer (2022): pilot programs for drone-based medical deliveries

• Literature highlighting existing gaps

o Comi & Savchenko (2021); Garus et al. (2024): comparisons of delivery methods

o Berenbrok et al. (2022); Sharareh et al. (2024): methodologies for calculating driving times

We believe these additions provide a stronger foundation for the aim and motivation of our study, clarifying the significance of addressing rural healthcare access challenges and the potential role of drone-based solutions.

3. Research Questions and Objectives:

o The research objectives are not mentioned in the paper, please mention the objectives of the paper.

Response: We have included the research objective in the last paragraph of the introduction. Please see “The primary research objective is to develop and assess a scalable framework that integrates drone-based delivery, spatial vulnerability analysis, and operational modeling to improve equitable healthcare access in disaster-prone rural regions.”

4. • Literature Review:

o Some more related papers can be included in the related work section.

Response: Thank you for your comments. We have added 11 additional references to the introduction section; details are provided in our response to Comment #2.

5. Methodology

• Clarity of Methods:

o The methods are stated clearly that is good.

• Innovativeness:

o The proposed approach is novel.

Response: Thank you for your comments.

6. Results and Analysis

• Presentation of Data:

o Presentation of the data is good.

o Some more details and references can be added in the introduction areas.

o More details can be added in the other sections like methodology and conclusion sections.

Response: Thank you for your comments. We have added 11 additional references to the introduction section to provide more context and support; details are provided in our response to Comment #2. We have added more details regarding the methodology in the introduction section: “this study compares traditional vehicle-based pharmaceutical delivery with drone-based systems in flood-prone coastal communities and evaluates patient vulnerability. Travel times were estimated for both delivery modes, and two vulnerability indices—one incorporating age and travel time (VAT) and another adding flood impacts (VATF)—were used to identify high-risk populations. Hotspot analysis guided prioritization of drone stations, demonstrating how drones can improve timely medication access for the most vulnerable residents.”

We have also added more details about methodology into the conclusion:“… this study assessed healthcare accessibility in flood-prone coastal communities by comparing traditional vehicle-based pharmaceutical trips with drone-based deliveries, while also evaluating patient vulnerability. Travel times for personal vehicles were calculated using a hierarchical road network and round-trip travel assumptions, whereas drone delivery times were estimated using direct flight paths from drone stations. Population layers were then aggregated within travel zones to quantify access efficiency. To identify the most at-risk populations, two vulnerability indices were developed: VAT, incorporating patient age and vehicle travel time, and VATF, additionally accounting for floodwater interruptions. Hotspot analysis identified statistically significant clusters of high vulnerability, guiding the prioritization of drone stations for service deployment. Overall, this integrated approach demonstrated how drones can improve timely access to medications, particularly for the most vulnerable populations, and provided a scalable framework for optimizing resource allocation under both everyday and flood-impacted conditions.”

7. • Analysis and Discussion:

o The results are well analyzed.

Response: Thank you for your comment.

8. Conclusion and Contributions

• Summary of Findings:

o The conclusion and future scope are stated good.

o But state what innovative method can be used in the future.

o State how your approach can help in the relevant field?

Response: In addition to a new paragraph on future directions in the Conclusion, we have edited the text to incorporate additional innovative methods: “Future research should enhance travel time estimates by incorporating real-world driving behaviors, dynamic traffic conditions, and more flexible drone routing systems, including multi-drone networks, station exchanges, and variable drone speeds. Improving the vulnerability scoring methodology by integrating health condition prevalence, behavioral factors, and community-specific thresholds could provide a more accurate assessment of patient needs. Addressing service gaps in no-fly zones through alternatives like truck-based drone delivery, conducting community surveys, and assessing human-drone interactions are also recommended. Finally, the geospatial dataset developed here offers a valuable foundation for cost-benefit analyses and stakeholder collaboration to expand efficient, adaptive, and community-informed drone-based healthcare delivery in rural, flood-prone regions.”

We have also added a statement regarding the contribution to the relevant field: “This approach helps improve healthcare access by identifying high-need populations, optimizing drone hub placement, and providing a scalable framework for resilient, equitable medication delivery in underserved communities.”

9. • Contributions:

o The contributions to the field are stated nicely.

o Some more details can be added in the conclusion part.

Response: We have included a paragraph regarding the main contributions of this manuscript in the conclusion section. Please refer to “The three main contributions of this study include: first, quantifying the substantial time savings of drone-based medication delivery compared to traditional vehicle travel; second, developing two spatial vulnerability indices that integrate demographic, geographic, and flood exposure data to identify and prioritize high-need patients; and third, evaluating drone hub performance and geographic reach under varying vulnerability profiles to guide effective placement and resource allocation. Together, these contributions demonstrate that drone delivery networks are not only feasible but also strategically valuable as more equitable and resilient alternatives to personal vehicle–dependent healthcare access in underserved coastal communities.”

10. Language and Writing Style

• Grammar and Clarity:

o Some very little mistakes in grammar, that can be revised.

Response: We have reviewed the manuscript and corrected identified typos; please refer to the tracked changes document for details.

11. References

• Relevance and Recency:

o The references are relevant.

o However the references provided are very less, some more references can added. I have also recommended some references you can add them and extend the referencing area.

Response: Thanks for your suggestion. The manuscript included 83 references in the prior round of revisions; we added 11 more references to the introduction to further strengthen the context, as detailed in our response to Comment #2. Additionally, we incorporated one of the specific references the reviewer suggested, as noted in our response to Comment #14. With these updates, the manuscript now cites 95 references, which we believe provides thorough and sufficient coverage.

12. • Formatting:

o References are in proper order.

o However some more related references can be added, some references are given below in the recommendations section.

Response: Thank you for your comment. We have added 11 more references to the introduction to further strengthen the context, as detailed in our response to Comment #2. We have included a reference that the reviewer suggested. Please see our response to comment #14.

13. Figures, Tables, and Equations

• Figures:

o The figures should be explain in more details inside the text.

• Tables:

o The tables should be explain in more details inside the text.

• Equations:

o Explain each parameter of the equation/algorithm.

Response: Thank you for your feedback. Since the comment did not specify which details were lacking, we focused on Figures 5–8 and Table 5 in the Results section to ensure their explanations are more comprehensive and better integrated. We hope this addresses your concern and improves the clarity and readability of the manuscript. We also have included more detailed explanations for equations and their parameters. Please refer to the Result section and the descriptions for equation.

14. Recommendations for Improvement

1. The introduction section can be furnished with some new papers like:.

a. https://doi.org/10.4108/airo.5855

b. Using the different AI methods : https://doi.org/10.1007/978-981-97-5979-8_8 , https://doi.org/10.1007/978-981-97-5979-8_7

other food deliravy robot: doi: 10.1109/ACCESS.2024.3355278.

Response: Thank you for providing these insightful articles. We appreciate the reviewer’s suggestions and have carefully considered each recommended reference. The paper “Moshayed et al., 2024 Robots in Agriculture: Revolutionizing Farming Practices” has been added to section 4.3 Study Limitations and Future Directions . This placement allows us to acknowledge its relevance to the broader field while keeping the introduction concise and closely aligned with the primary goals of our study.

We also reviewed the book chapters “Moshayedi et al., 2024 Meta-heuristic Algorithms as an Optimizer: Prospects and Challenges (Part I and II).” However, we found it challenging to establish a direct connection between meta-heuristic algorithms and our current application, which focuses on spatial and vulnerability-driven modeling rather than algorithm optimization.

Finally, regarding “Moshayedi et al., 2024 Design and Development of FOODIEBOT,” we determined that food delivery robotics fall outside the scope of this manuscript, which is centered on healthcare-focused drone delivery in flood-prone rural communities. For this reason, we did not include this reference.

15. Please answer below question

How did drone delivery compare to traditional personal vehicle travel times for medication delivery in Virginia’s Eastern Shore?

Response: Drone delivery was markedly faster. Over 80% of Eastern Shore patients could receive medications within 10 minutes by drone, whereas many remote communities faced vehicle round trips of 20-50 minutes to the nearest pharmacy. In places without practical vehicle access, such as Tangier Island, drones reduced delivery time to under 10 minutes and provided a viable alternative to boat or plane transport.

16. What factors were incorporated into the transportation vulnerability indices developed in this study?

Response: The vulnerability indices incorporated three main factors: patient age, vehicular travel time to the nearest pharmacy, and flood-related travel interruptions. Patient age was assessed by calculating the percentage of individuals aged 60 and older in each census block and assigning those values to building footprints. Vehicular travel time was determined by calculating the shortest driving routes from each building footprint to the nearest pharmacy. Flood-related interruptions were evaluated using FEMA 100-year flood zones and road networks to categorize each property’s access as not affected, detoured, blocked, or inundated. Two indices were created: VAT, which included age and travel time, and VATF, which added flood interruption to capture the additional impact of flooding on patient access.

17. Which area was identified as having the highest concentration of vulnerable patients, and why?

Response: The western coast of the Eastern Shore was identified as having the highest concentration of vulnerable patients. This area’s elevated vulnerability is largely due to its low-lying, flood-prone conditions, which, when factored into the VATF index, increased vulnerability scores and created concentrated hotspot patterns in the spatial analysis.

18. What role did community engagement and collaboration with multiple organizations play in the project’s success?

Response: Community engagement and collaboration were critical to the project’s success. Local stakeholders, healthcare providers, drone service experts, and academic researchers worked together to address complex transportation barriers and design an effective, data-driven drone delivery network. The Accomack-Northampton Planning District Commission facilitated community outreach, ensuring local needs were understood and addressed. Healthcare providers like Riverside Health guided the medical delivery requirements, while DroneUp provided the technical expertise and operations. Academic partners supported project management and data modeling. This transdisciplinary collaboration ensured that the system was both technically feasible and responsive to the community’s healthcare needs.

19. What future improvements to the vulnerability scoring methodology and service delivery were recommended by the study?

Response: We recommended refining the vulnerability scoring methodology by integrating additional factors, such as the prevalence of health conditions like hypertension and behavioral aspects related to driving patterns b

Attachment

Submitted filename: Responses to reviewer Sept 4.docx

pone.0333696.s003.docx (35.8KB, docx)

Decision Letter 2

Zeashan Hameed Khan

17 Sep 2025

Drone-Based Medication Delivery for Rural, Flood-Prone Coastal Communities

PONE-D-25-20755R2

Dear Dr. Chen,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

Kind regards,

Zeashan Hameed Khan, Ph.D.

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

The revised version is sufficiently improved and hence can be accepted in the present form.

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #2: (No Response)

Reviewer #3: All comments have been addressed

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2. Is the manuscript technically sound, and do the data support the conclusions?

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Reviewer #2: (No Response)

Reviewer #3: Yes

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3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #2: (No Response)

Reviewer #3: Yes

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4. Have the authors made all data underlying the findings in their manuscript fully available?

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Reviewer #2: (No Response)

Reviewer #3: Yes

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5. Is the manuscript presented in an intelligible fashion and written in standard English?

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Reviewer #2: (No Response)

Reviewer #3: Yes

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6. Review Comments to the Author

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Reviewer #2: (No Response)

Reviewer #3: The authors have carefully addressed all of my previous concerns, and the paper has undergone substantial revisions. I believe these changes have significantly improved the overall clarity, quality, and contribution of the work. The revised version is more coherent, and the presentation of results is much stronger compared to the earlier draft. Overall, I am satisfied with the responses provided and the improvements made.

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Reviewer #2: No

Reviewer #3: No

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Acceptance letter

Zeashan Hameed Khan

PONE-D-25-20755R2

PLOS ONE

Dear Dr. Chen,

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Thank you for submitting your work to PLOS ONE and supporting open access.

Kind regards,

PLOS ONE Editorial Office Staff

on behalf of

Dr. Zeashan Hameed Khan

Academic Editor

PLOS ONE

Associated Data

    This section collects any data citations, data availability statements, or supplementary materials included in this article.

    Supplementary Materials

    Attachment

    Submitted filename: Response to Reviewer_medical delivery in ES June 30.docx

    pone.0333696.s002.docx (32.6KB, docx)
    Attachment

    Submitted filename: Responses to reviewer Sept 4.docx

    pone.0333696.s003.docx (35.8KB, docx)

    Data Availability Statement

    All the geospatial outcomes are available from the Harvard Dataverse (webpage: https://dataverse.harvard.edu/dataverse/DroneDOTSMART).


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