Travel Health Needs of Children in U.S. Military Families Stationed Abroad

ABSTRACT

Introduction

While the U.S. DoD mandates preventive health measures for service members overseas, the health needs of their accompanying children are poorly described. This study aims to quantify and characterize the recommended travel health preventive services, with attention to malaria, dengue, yellow fever, Japanese encephalitis, tick-borne encephalitis (TBE), typhoid, and rabies, in military-connected expatriate children.

Materials and Methods

The registered country of residence of active duty service members and their families in December 2022 as reported by the Defense Manpower Data Center was assessed to quantify military-connected children living abroad. Data were sorted by age group and geographic Combatant Command. Country-level populations were mapped against CDC Yellow Book Health Information for International Travel country guidelines and Shoreland Travax recommendations.

Results

In 2022, there were 63,592 children of active duty service members living abroad. The largest populations were in Indo-Pacific Command (INDOPACOM) and European Command regions, reflecting long-standing bases in the regions. Of all conditions studied, Japanese encephalitis posed risk to the largest number of military children. Within INDOPACOM, 25,161 had regional to widespread endemic risk, while 357 children lived in countries with rare/focal risk for transmission. Relatively few children lived in areas with endemic risk for the other studied mosquito-borne illnesses, malaria (7454), dengue (3377), and yellow fever (533). With the emergence of TBE in much of Europe, 29,752 children were living in regions with some TBE risk. Only 1609 children lived in regions with both wildlife and domestic canine transmission cycles of rabies established. Typhoid risk for 13,607 children, largely in INDOPACOM, was sufficiently high for vaccination to be recommended for long-term travelers by the CDC and Travax.

Conclusions

Military-connected children living abroad have differing preventive health service needs from their counterparts in the United States. With these children living in countries with and without permanent military bases, there is a clear need for further investigation with attention to both uptake of preventive measures and incidence of disease. While risk assessments for any particular travel are unique and very much itinerary- and activity-specific, the risk stratification and terminology applied are both practical and consistent with the guidelines and resources available to clinicians. While for some children, risk may be overestimated because of their specific location within a country, there is also likely underestimation of risk assumed with regional travel to other countries with increased risk profiles. Understanding the utilization of preventive services and associated health outcomes in this population is crucial for their well-being.

INTRODUCTION

The U.S. Military Health System (MHS) provides care to 9.6 million beneficiaries, including service members, retirees, and their family members, both in the United States and abroad.¹ Approximately 1.9 million children under 18 years old are eligible for care, of whom 880,000 are children of active duty service members, with the remainder in reserve component or military retiree families. Ninety-five percent of beneficiaries reside in the United States. In fiscal year 2022, the Defense Health Agency reported that 170,000 active duty service members and 120,000 of their family members were residing outside the United States. (not including those on temporary deployments). There are limited data published regarding the health needs and outcomes of military children residing outside the United States.

The U.S. DoD mandates certain preventive health measures for service members serving abroad; however, these interventions are not mandated for family members.^2,3 Before moving to any new duty station, typically for 2- to 3-year tours of duty, family members are required to complete health screenings to ensure the availability of necessary medical care. These health screenings are of particular importance to those moving to geographically remote or medically underserved locations. This screening requirement typically involves a single health appointment where an administrative review of the patient’s health record is conducted and the associated paperwork is completed. Before any travel, whether it is short-term travel or an ex patria/long-term travel, pretravel counseling is recommended for vaccines and other location-specific disease prevention approaches, using the guidance provided by the U.S. Centers for Disease Control and Prevention (CDC). However, within the DoD, there is no uniform mechanism to monitor completion of these CDC recommendations for family members in either the initial screening process or a separate dedicated pretravel health visit, despite counseling and immunizations being readily available at little to no cost to the patient. A recently released DoD Instruction has directed Military Treatment Facilities to improve uniformity for this “Family Member Travel Screening” that includes a provision for immunization counseling, but it does not address an enforcement mechanism or tracking of adherence with CDC recommendations.^4,5

The scale, utilization, and outcomes of travel-specific prevention interventions in this population of long-term ex patria children of active duty service members are yet to be described. As an initial effort to better describe the health needs of military children residing overseas, we aim to quantify and characterize the scope and scale of recommended travel health preventive services, with particular attention to malaria, dengue, yellow fever (YF), Japanese encephalitis (JE), tick-borne encephalitis (TBE), typhoid, and rabies.

METHODS

We conducted a comprehensive analysis using administrative data from the U.S. Military’s Defense Enrollment Eligibility Reporting System (DEERS). Using the “DEERS Mailing Address Family, Age, Location Report,” we determined the registered country of residence for active duty service members and quantified the total number of children less than 18 years of age who were living abroad in December 2022. Data were stratified by age group (0-5 and 6-17 years) because of the higher vulnerability to infectious diseases of children under 5 years (Table 1). Countries of residence were aggregated into the 6 geographic Combatant Commands. Combatant Commands represent how the DoD organizes regions for command oversight of force health protection policies including vaccine recommendations: Africa Command (AFRICOM), Central Command (CENTCOM), European Command (EUCOM), Indo-Pacific Command (INDOPACOM), Northern Command (NORTHCOM) not including Canada or the 50 United States, and Southern Command (SOUTHCOM).⁶ An Arc-geographic information system threat-based map of the Combatant Commands was generated (Esri, Vienna, VA and Phylopic.org). Children of reservists and retirees, as well as those living in the continental United States, Alaska, Hawaii, and Canada, were excluded. We cross-referenced the CDC Yellow Book: Health Information for International Travel and Shoreland Travax for recommended disease-specific guidelines on pretravel health services, with attention to pediatric indication for chemoprophylaxis or vaccines for malaria, dengue, YF, JE, TBE, typhoid, and rabies.^7,8 We aggregated results by age group, geographic region, and medical threat intensity. Nomenclature for intensity of risk was adopted directly from the Yellow Book and Travax; for example, “regional to widespread” risk was applied when prophylaxis or vaccination would be routinely recommended for all travelers or there was transmission risk across a plurality of populated areas. “Rare/focal risk” was assessed for places in which vaccines or prophylaxis would not typically be recommended unless there was a specific, itinerary-based risk factor.

Table 1.

Children of U.S. Military Active Duty Personnel Living Abroad^a in 2022.

Geographic Combatant Command	0 to 5 years old	6 to 17 years old	Total
AFRICOM	156	200	356
CENTCOM	299	561	860
EUCOM	12,887	18,356	31,243
INDOPACOM	12,277	16,753	29,030
NORTHCOMa	517	1,018	1,535
SOUTHCOM	184	384	568
Total	26,320	37,272	63,592

The data represent a cross-reference of the Defense Enrollment Eligibility Reporting Systems Mailing Address Family, Age, Location Report from December 2022 with the DoD Combatant Commands.

^aExcludes the 50 U.S. States and Canada.

Abbreviations: AFRICOM, Africa Command; CENTCOM, Central Command; INDOPACOM, Indo-Pacific Command; EUCOM, European Command; NORTHCOM, Northern Command; SOUTHCOM, Southern Command.

This study represents the results of a subanalysis in the Deployment and Travel Health: Knowledge, Attitudes, Practice, and Outcomes Study (KAPOS) supported by the DoD’s Infectious Disease Clinical Research Program. Knowledge, Attitudes, Practice, and Outcomes Study aims to quantify the burden and distribution of deployment and travel-associated disease within the MHS in order to inform policy and practice guidelines that will decrease the burden of disease and improve quality of care. Knowledge, Attitudes, Practice, and Outcomes Study received Institutional Review Board approval at the USU with appropriate considerations for human subjects research.⁹

RESULTS

In 2022, 63,592 children of active duty service members aged 17 years and younger lived abroad in the 6 regions of interest, as reported by the Defense Manpower Data Center (Table 1). An additional 4194 children were identified without a specified region of residence. There were 25,320 children aged 5 years or younger, and 37,272 were 6 to 17 years old. The largest populations were located in countries within INDOPACOM (n = 29,030) and EUCOM (n = 31,243), reflecting long-standing bases in Japan, Korea, Guam, Germany, the United Kingdom, and Italy. Figure 1 represents infectious disease risk by Combatant Command. Population counts relative to exposure to diseases of interest and recommended prevention strategies are outlined in Tables 2 and 3.

Figure 1.

Select infectious disease risk by U.S. DoD Region in 2022.

Table 2.

Number of Children by Region with Exposure Risk for Selected Mosquito Transmitted Disease.

Malaria	0 to 5 years old				6 to 17 years old
	No risk	Rare cases/focal endemicity	Regional to widespread endemicity		No risk	Rare cases/focal endemicity			Regional to widespread endemicity
AFRICOM	12	20	124		24	34			142
CENTCOM	292	7	0		545	15			1
INDOPACOM	9443	2813	21		12,817	3902			34
NORTHCOM	502	15	0		994	24			0
SOUTHCOM	85	62	37		181	142			61
Total	10,334	2917	182		14,561	4117			238
Yellow fever	0 to 5 years old				6 to 17 years old
	No risk	Rare cases/focal endemicity	Regional to widespread endemicity		No risk	Rare cases/focal endemicity				Regional to widespread endemicity
AFRICOM	36	27	93		60	31				109
SOUTHCOM	92	43	49		203	91				90
Total	128	70	142		263	122				199
Japanese encephalitis virus		0 to 5 years old			6 to 17 years old
	No risk	Rare cases/focal endemicity		Regional to widespread endemicity	No risk		Rare cases/focal endemicity			Regional to widespread endemicity
INDOPACOM	1493	134		10,650	2019		223			14,511
Denguea	0 to 5 years old				6 to 17 years old
	No evidence of risk	Sporadic/uncertain risk		Frequent/continuous risk	No evidence of risk			Sporadic/uncertain risk		Frequent/continuous risk
AFRICOM	14	112		30	32			134		34
CENTCOM	274	25		0	498			63		0
EUCOM	12,887b	0		0	18,356b			0		0
INDOPACOM	11,925	165		187	16,042			292		419
NORTHCOM	50	0		467	98			0		920
SOUTHCOM	15	23		146	24			63		297
Total	25,165	325		830	35,050			552		1,670

This table represents a cross-reference of administrative data from the Defense Enrollment Eligibility Reporting Systems Mailing Address Family, Age, Location Report from December 2022 with the DoD Combatant Commands and country-specific recommendations from CDC Yellow Book: Health Information for International Travel and Shoreland Travax.

^aCDC Yellow Book defines dengue regional risk as “No evidence of risk,” “Sporadic/uncertain risk,” or “Frequent/continuous risk.”

^bEmerging risk with cases now reported in Italy, France, and Spain.

Abbreviations: AFRICOM, Africa Command; CDC, U.S. Centers for Disease Control and Prevention; CENTCOM, Central Command; EUCOM, European Command; INDOPACOM, Indo-Pacific Command; NORTHCOM, Northern Command; SOUTHCOM, Southern Command.

Table 3.

Number of Children by Region with Exposure Risk for Tick-Borne Encephalitis, Rabies, and Typhoid.

Tick-borne encephalitis 0-5 years old						6-17 years old
	No risk		Rare cases/focal endemicity		Widespread endemicity	No risk	Rare cases/focal endemicity		Widespread endemicity
AFRICOM	151		5		0	195	5		0
CENTCOM	292		7		0	547	14		0
EUCOM	623		12,220		44	868	17,425		63
INDOPACOM	12,273		4		0	16,739	14		0
Total	13,339		12,236		44	18,349	17,458		63
Rabiesa		0-5 years old				6-17 years old
		Wildlife species only		Dogs and wildlife		Wildlife species only		Dogs and wildlife
AFRICOM		0		156		3		197
CENTCOM		257		42		469		92
EUCOM		12,848		39		18,284		72
INDOPACOM		12,108		169		16,374		379
NORTHCOM		502		15		994		24
SOUTHCOM		46		138		98		286
Total		25,761		559		36,222		1050
Typhoidb		0-5 years old				6-17 years old
		No risk		At risk c		No risk		At risk
AFRICOM		0		156 (39)		0		200
CENTCOM		12		287 (81)		35		526
INDOPACOM		7895		4382 (1,448)		10,652		6,101
NORTHCOM		50		467 (132)		98		920
SOUTHCOM		0		184 (38)		0		384
Total		7957		5476 (1,738)		10,785		8,131

This table represents a cross-reference of administrative data from the Defense Enrollment Eligibility Reporting Systems Mailing Address Family, Age, Location Report from December 2022 with the DoD Combatant Commands and country-specific recommendations from CDC Yellow Book: Health Information for International Travel and Shoreland Travax.

^aU.S. Centers for Disease Control and Prevention considers endemicity to be worldwide with some countries categorized as rabies virus–free with unclear wildlife burden. U.S. Centers for Disease Control and Prevention develops recommendations based on risk of rabies exposure (i.e., presence of canine rabies and planned activities of traveler) and availability of postexposure prophylaxis.

^bRisk or no risk is based on CDC recommendation for vaccination because of endemicity by country.

^cNumbers in parentheses indicate children under the age of 2 years, who are unable to receive the Vi capsular polysaccharide vaccine.

Abbreviations: AFRICOM, Africa Command; CDC, U.S. Centers for Disease Control and Prevention; CENTCOM, Central Command; EUCOM, European Command; INDOPACOM, Indo-Pacific Command; NORTHCOM, Northern Command; SOUTHCOM, Southern Command.

Mosquito-borne illnesses pose a significant ongoing risk to military children located in all regions excluding EUCOM, where there is emerging risk (Table 2). Malaria risk was classified as regional to widespread for 420 children, with the majority of those children residing in AFRICOM nations. Rare or focal risk of malaria existed within the country of residence for 7034 children, mainly residing in INDOPACOM. Yellow fever endemicity across the range of focal to widespread represents a threat to 533 children within AFRICOM and SOUTHCOM. Of all conditions studied, JE posed risk to the largest number of military children living abroad. Within INDOPACOM, 25,161 had regional to widespread endemic risk, while 357 children lived in countries with rare/focal risk for transmission. Dengue represents a sporadic/uncertain risk for 877 children, while 2500 had exposure risk classified as frequent/continuous by the CDC Yellow Book. However, with emerging risk in Europe, there is the potential in the future for considerably more at risk military-connected children.

Population and risk categorization for TBE, rabies, and typhoid are outlined in Table 3. There were 29,694 children, predominantly from EUCOM, with rare/focal risk of exposure to TBE virus, but only 107 living in countries with regional to widespread risk. While 61,983 children lived in countries with rabies established in wild animal populations, only 1609 lived in regions with both wildlife and domestic canine transmission cycles established. Typhoid risk for 13,607 children, largely in INDOPACOM, was sufficiently high for vaccination to be recommended for long-term travelers (which includes military families stationed abroad) by the CDC and Travax.

DISCUSSION

This study examines the distribution of military-connected children stationed overseas in DoD regions in relation to endemic infectious diseases, many of which are vaccine- or prophylaxis-preventable, a topic that has not previously been studied in a systematic manner. Colonel Leo Geppert’s 1958 analysis of pediatric admissions to U.S. Military hospitals in Tokyo, Japan, and San Antonio, Texas, was the first attempt to describe incident disease burden in a population of military children living abroad.¹⁰ Since then, little has been published on the travel-specific health threats these children may encounter; instead, efforts have focused on the social stressors or health system and associated medical training requirements.^11–14 Prospective cohort studies within military families have studied disease incidence in short-term travelers but not ex patria populations.¹⁵ This gap contrasts efforts to surveil and report on travel and deployment-related diseases in service members.^16,17 This population of 63,592 children under the age of 18 years accounts for approximately 7.2% of all children of active duty service members and merits consideration for their unique health risks and outcomes. We review annual population estimates for those stationed overseas in a region with transmission risk for malaria, dengue, YF, JE, TBE, typhoid, and rabies.

Malaria

U.S. Centers for Disease Control and Prevention surveillance data show that children comprise approximately 16% of reported malaria cases in US citizens and that among travel-associated cases, the use of effective chemoprophylaxis is low.¹⁸ Within our study’s population, we found that 420 children of service members, 43.3% of whom were aged 5 years or under, were living in countries with widespread endemicity and near-universal recommendations for chemoprophylaxis. Another 7034 may require chemoprophylaxis, depending on where they live or travel within the country of residence. A total of 266 were located in AFRICOM, where there is a higher prevalence of Plasmodium falciparum, the most likely species of malaria to cause severe or life-threatening disease. There are no published data on the use and adherence to chemoprophylaxis in this population, nor even analogous populations such as Department of State embassy-based families. However, there is evidence within the MHS that provider specialty type can influence the type of chemoprophylaxis recommended and the risk-of-resistance-related appropriateness of the medication.^9,19 While anecdotal cases of malaria among these children are known to have occurred, there are no published data on the burden of malaria cases among military-connected children living abroad.

Japanese Encephalitis

The risk of acquiring JE virus infection is confined exclusively to INDOPACOM. Because of the significant military presence in Japan and Korea, we found that 25,161 children lived in areas with regional to widespread endemicity, with another 357 in areas with rare cases/focal endemicity—making it, of the diseases we studied, the threat impacting the greatest number of military children. The JE vaccine is approved for children 2 months and older. While DoD policies since 2015 have encouraged vaccination of all eligible family members living in threat areas, the uptake rate for both primary and booster doses is unknown, nor have this population’s barriers to immunization been studied.²⁰

Dengue Fever

While in recent history considered to be endemic in Central America, South America, Southeast Asia, and parts of Africa, cases of dengue have now been reported in Italy, France, and Spain.²¹ The risk of dengue fever in U.S. Territories such as Puerto Rico, the U.S. Virgin Islands, and American Samoa is well known with the risk now expanding to the continental United States, including Texas and Florida.²² The CDC’s guidance for travelers defines dengue transmission risk using categories of “no evidence of risk,” “sporadic/uncertain risk,” or “frequent/continuous risk.” We found that 2500 children of active duty service members live in areas of frequent/continuous risk of dengue, with another 877 in areas of sporadic/uncertain risk. As the risk of dengue endemicity spreads throughout Europe, more than 30,000 children of service members could be at risk. Safe and effective vaccine candidates have been an elusive goal given the need to provide equally high protection rates against all 4 serotypes or risk increasing the potential for severe dengue in subsequent infections. There is an FDA-approved and available vaccine, Dengvaxia™ (Sanofi Pasteur), for children ages 9 to 16 years living in dengue-endemic areas but only for those with a laboratory-confirmed previous dengue infection; additionally, this vaccine requires 3 doses separated by 6 months in order to provide full protection.²³ However, in June 2024, the manufacturer announced cessation of manufacturing because of lack of worldwide demand, an issue highlighting the limited population of military children that would be eligible to use this vaccine despite the overall threat of dengue infection. While other vaccines are in advanced clinical trials or in use in other countries, most notably QDenga™ (Takeda), which is available for children 4 years and older in several regions across the world including the European Union, it is not currently approved in the United States, nor is there an active application with the FDA.^24,25 Furthermore, the scale of threat posed by dengue mirrors that of both Zika virus and chikungunya virus, which all have the same primary vectors and overlapping geographic regions of risk. In the future, the chikungunya vaccine currently licensed for individuals 18 years and older as a single dose may play a role in expanding the protection of these children against emerging arbovirus threats.²⁶

Yellow Fever

Yellow fever poses a risk within both AFRICOM and SOUTHCOM nations. We identified 341 children living in areas with regional to widespread endemicity and another 192 in areas with rare or focal endemicity. Currently, the YF vaccine is approved and recommended for all individuals 9 months old or older traveling to regions or living in countries with endemic transmission. While this would apply to most military-connected children stationed in at risk areas, the 6- to 9-month-old population poses a unique challenge. In this age group, the live attenuated vaccine can be considered for those who are considered highest risk, largely based on duration of travel or intensity of transmission; however, its use must be weighed against the increased risk of severe complications, particularly YF vaccine-associated neurologic disease (e.g., meningitis, encephalitis, and Guillain Barré syndrome), which has an incidence of 50-400 cases per 100,000 infants vaccinated between the age of 6 to 9 months.²⁷ Yellow fever vaccine is contraindicated in infants under 6 months, and they are dependent on daytime mosquito bite prevention methods and in utero passively acquired immunity. While uptake of YF vaccine is likely high because it can be a criterion for crossing international borders under the International Health Regulations, its usage in military-connected children, particularly those in the 6- to 9-month age range, has not been described.

Tick-Borne Encephalitis

While TBE is found throughout many EUCOM nations, focal endemicity and rare cases also occur in AFRICOM, CENTCOM, and INDOPACOM. In our study population, 107 children with 44 under the age of 5 years were at risk of widespread exposure because of their location in EUCOM, whereas another 29,694 lived in countries, particularly Germany, reporting focal endemicity or rare cases. The risk of acquiring TBE is highest in spring and summer when participating in outdoor activities with elevated exposure to the Ixodes tick.²⁸ There is an FDA-approved TBE vaccine available to children 1 year and older. Yet, implementation within the MHS has been limited, with European medical facilities often referring those interested in the vaccine to local civilian clinics.²⁹ While most military-connected children in EUCOM live in areas where the risk is currently assessed as low, taking a detailed history of planned activities abroad is imperative to more accurately assess risk and need for vaccination. Between 2017 and 2021 there were 11 cases in MHS beneficiaries reported in Europe, including 4 in family members or service retirees—a sharp rise from the single case reported in the 5 years prior.³⁰ As with dengue fever, rising temperatures and shifts in vector ecology may intensify the risk to military families living in Europe.

Typhoid

The CDC estimates that approximately 5700 cases of typhoid, almost all travel-associated, occur each year in the United States.³¹ Two vaccines for typhoid exist: a live attenuated oral vaccine and the injectable Vi capsular polysaccharide formulation. Children 6 years and older can take the oral vaccine, which requires 4 doses over 8 days. A booster is required every 5 years. The injectable form of the vaccine is a single dose given to individuals older than 2 years old, with a booster needed every 2 years.³² Anecdotally, the injectable vaccine is more readily available at DoD facilities and is utilized by traveling families if offered. Currently, there are no vaccines available for children under 2 years old. We found that 13,607 children of service members live abroad in typhoid-endemic areas where CDC and Travax would recommend the vaccine, particularly to long-term travelers. Of those children, 1738 were under 2 years old and thus ineligible for either FDA-licensed vaccination. Anecdotally, we believe that there is little utilization of typhoid vaccine among children living on U.S. Military bases in South Korea and Guam. While little is known about the actual burden of typhoid in the U.S. Military pediatric population, the under 2-year age group is a uniquely vulnerable population and more likely to experience complications. A protein-conjugate vaccine is prequalified by the World Health Organization for use down to 6 months of age and, if licensed in the United States, could serve as an opportunity to broaden the population protected among both ex patria and domestically stationed military families that travel.³³ Although more immunogenicity data would be needed, it is also possible that, like other protein-conjugate vaccines, it would provide more durable protection and less frequent need for boosting than the VI capsular polysaccharide vaccine.

Rabies

Animal bites, with concomitant potential rabies exposure, are equally common among travelers of both short- and long-term duration, with canine and nonhuman primates being the most common animals involved.³⁴ Canine bites to children are the most common cause of human rabies worldwide, resulting from either lack of recognition of risk or inability to access preventive therapy. Thus, rabies and bite prevention and management, more generally, are topics that must be discussed with families preparing to travel abroad.³⁵ In a prospective study of military family travelers, close contact animal exposures were more common among children than adults, yet adults had higher rates of rabies pre-exposure vaccination.¹⁵ Anecdotally, military families stationed at the US embassies and living close to local communities of regions with endemic canine rabies—as opposed to regions with rabies limited to wildlife species only—are typically offered pre-exposure vaccines. In contrast, those living on large US bases with access to Military Treatment Facilities are counseled on bite avoidance, management, and postexposure prophylaxis. The uptake of pre-exposure prophylaxis, incidence of animal bites, and utilization of postexposure prophylaxis in the ex patria military child population are unknown. Given the ease with which military families abroad may visit countries with different risk profiles, the known challenges in accessing the recommended postexposure prophylaxis in many civilian medical facilities abroad, and the recent shift to a 2-dose pre-exposure prophylaxis regimen with less stringent booster requirements for many travelers, reconsideration of how this vaccine is employed, particularly among military children living abroad, may be warranted.³⁵

Study Strengths and Limitations

This study is an initial attempt to provide a landscape analysis of some of the significant travel-associated, preventable diseases that the children of U.S. Military service members living overseas may face. This analysis benefits from the ability to utilize DoD workforce data to assess in detail the location-specific medical threats coupled with clear policy guidance from multiple authoritative organizations. Although we describe these threats and the population size impacted at the regional level, we did this to align with other public-facing reports by the DoD and to ensure that describing in detail small groups of military-connected children living in particular countries did not pose a security risk. While risk assessments for any travel are unique and very much itinerary- and activity-specific, both the risk stratification and terminology applied are practical and consistent with the guidelines and resources available to clinicians. It is anticipated that, for some children, risk may be overestimated because of their specific location within a country. Likewise, there is presumably some underestimation of additional risk assumed with unique activities or regional travel to other countries with increased risk profiles. Future work may consider analysis of active and passive surveillance and medical encounter data for this unique patient population. Such studies could address many of the questions raised by our findings to better understand and address the health risks faced by military-connected children living overseas.

CONCLUSION

Children living as expatriates overseas are a unique risk population for a variety of infectious diseases and other travel-related conditions, yet epidemiological information on this population is scant. Children of U.S. Military active duty service members are a unique subset of this population that has not been systematically studied in more than 60 years. Our findings highlight the need for a better understanding of disease burdens and utilization patterns for chemoprophylaxis and vaccination, which could inform policies, guidelines, and additional medical research initiatives focused on potential medical threats in expatriate children. The unique status of U.S. Military children who relocate alongside military parents not only positions them as a possible sentinel population but also warrants extra precautions to protect their health while they accompany their parents in efforts to protect national health and security.

FUNDING

This study was supported by the Infectious Disease Clinical Research Program, a DoD program executed through the USU through a cooperative agreement with The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc. This project was funded in whole, or in part, with federal funds from the National Institute of Allergy and Infectious Diseases, National Institutes of Health (Inter‐Agency Agreement Y1-AI-5072), and the Defense Health Program, U.S. DoD (HU0001190002).

CONFLICT OF INTEREST STATEMENT

None declared.

DATA AVAILABILITY

The data that support the findings of this study are available on request from the Defense Manpower Data Center.

INSTITUTIONAL REVIEW BOARD (HUMAN SUBJECTS)

IDCRP-097.

INSTITUTIONAL ANIMAL CARE AND USE COMMITTEE

Not applicable.

INSTITUTIONAL CLEARANCE

Institutional clearance is approved for this study.

INDIVIDUAL AUTHOR CONTRIBUTION STATEMENT

P.W.H. conceptualized and designed the study, obtained the data, contributed to data analysis, and reviewed and revised the manuscript.

A.P.M. and A.M.D. designed the study and data collection instruments, carried out the initial analyses, and reviewed and revised the manuscript.

E.H.L. contributed to data analysis, designed figures, and reviewed and revised the manuscript.

All authors approved the final manuscript as submitted and agree to be accountable for all aspects of the work.