Lessons from Contact Tracing in Mid-Missouri

Abstract

The public health community has used contact tracing to address pandemics since the eighteenth century. With the emergence of COVID-19, these classical skills are the primary defense for communities to limit morbidity and mortality during the pandemic. Here we describe the methods, strengths, and challenges of contact tracing.

Introduction

On December 31, 2019, the World Health Organization (WHO) was notified of an emerging pneumonia-like illness of unknown etiology within the city of Wuhan, China.¹ Identification of SARS-CoV-2 as the causative agent of this illness, termed COVID-19, followed soon after the outbreak. Despite the rapid development of an international crisis management team, a global preparedness plan to increase production and distribution of personal protective equipment (PPE), and extensive travel restrictions, COVID-19 rapidly spread across the world, leaving twin public health and economic crises in its wake.

COVID-19 has placed an incredible amount of stress upon the public health, research, and biomedical communities. Despite both science and medicine advancing at an unprecedented pace much remains unknown about this virus. This year COVID-19 migrated from the northeast, to the Sun Belt, and now has set solidly into the midwest. In Missouri the prevalence was low until mid-summer, but now we face a dramatic increase in cases, especially among younger people. With no natural immunity, and with widespread vaccinations and herd immunity in its earliest stages, case burden will likely continue to increase. Public health officials also anticipate sustained community transmission of COVID-19 this winter and spring, especially as adherence to public health recommendations wanes amid “caution fatigue.” As with the 1918 Spanish flu pandemic, we have primarily relied on nonpharmaceutical interventions to limit the spread of this novel coronavirus, including social and physical distancing, an emphasis on handwashing, situational awareness, and contact tracing with both isolation of COVID-19 positive patients and quarantine of their close contacts.

What is Contact Tracing? Why Does It Matter?

Soon after COVID-19 emerged, the WHO recommended public health agencies engage in contact tracing and quarantining of exposed individuals to slow the progression of the virus. Public health professionals use contact tracing as a means to follow and establish control of outbreaks. This practice was first developed by John Haygarth to prevent the spread of smallpox during the eighteenth century.^2–4 Since its inception, public health officials have utilized contact tracing for infection control during nearly every major epidemic and pandemic, including STIs, HIV/AIDs, tuberculosis, and smallpox. In 2020, contact tracing has been critical for effectively isolating and limiting the spread of COVID-19 in many countries.

There are three major components of contact tracing:^2,5

1. Identification of a primary case through symptoms, subsequent testing, and mandatory reporting to the health department. The primary case is considered a “person under investigation” (PUI) and needs to be isolated throughout the infectious period.

2. Outreach to any individuals that the PUI came in close contact with, during the predicted infectious period of the illness.

3. Quarantine of these contacts with monitoring for symptom development over the incubation period of the disease.

If the contact tests positive, that individual becomes a new primary case, and contact tracers repeat the process for the subsequent case. When adequately staffed, this system efficiently prevents the spread of disease by limiting contact between exposed and non-exposed individuals. Contact tracing is a well-vetted technique that has effectively limited the spread of COVID-19 in countries such as Taiwan, South Korea, and New Zealand, even in the absence of a vaccine; those countries have enjoyed widespread public support of strong public health measures to combat COVID-19, partly because of their unfortunate experiences with the 2002–2004 SARS and 2012 MERS outbreaks.

Effectively Using Contact Tracing to Limit Community Transmission of COVID-19

Contact tracing has become a household catch-phrase during the pandemic. However, many people still have questions about what is considered a “close contact.” The CDC recommends contact tracing to identify close contacts of an individual with a laboratory-confirmed or suspected COVID-19 infection. These guidelines further define a “close contact” as any individual within six feet of a PUI for at least 15 minutes in a 24-hour period during the time that the PUI was infectious. From a public health perspective, this infectious period starts two days before the onset of symptoms (or two days before a positive test, if the PUI is asymptomatic) and ends once the PUI enters isolation.^5–6

There have also been conflicting recommendations regarding testing procedures for close contacts. As of August 31, 2020, the CDC has recommended that in jurisdictions with testing capacity, symptomatic, and asymptomatic close contacts to patients with confirmed and probable COVID-19 should be evaluated and monitored. Implementation of this recommendation is often dependent on availability of local resources, especially with different testing modalities now available (including PCR, antigen testing and at-home testing, each of which have different test performance characteristics).

Quarantine and isolation are two other terms that are sometimes misunderstood or used interchangeably but mean different things. Quarantine is recommended for exposed contacts, while isolation is to prevent spread from confirmed cases. CDC has recommended that close contacts to confirmed or suspected COVID-19 cases self-quarantine for a full 14 days after the last potential exposure to the PUI. In some cases, such as for asymptomatic individuals, quarantine duration may be reduced to 10 days, or seven days following a negative COVID-19 test; however, ending quarantine early requires close symptom-monitoring, mask-wearing at all times around others, and avoiding contact with high-risk individuals for the full 14 days.⁷ The most precautious approach is still full quarantine for 14 days. Any close contact who develops symptoms of COVID-19 should isolate immediately and get tested. Any close contact who tests positive for COVID-19, whether asymptomatic or symptomatic, should then be managed as a primary case and isolate for 10 days minimum.

Interviewing COVID-19 cases and contact tracing is extremely labor-intensive for local health departments. Since the arrival of COVID-19, local health department employees and volunteers have worked diligently to keep up with case investigations and contact tracing protocols to limit viral spread within their communities.⁸ In Boone County, Missouri, the goal of the Columbia-Boone County Department of Public Health and Human Services (PHHS) has been for a staff member to interview every PUI within 48 hours to gather CDC-required case information. The staff member instructs the PUI on isolation procedures and gathers the names of all identifiable close contacts. PHHS contact tracers then notify these individuals that they have been identified as close contacts to a case of COVID-19, and they are instructed to quarantine for 14 days from the time of their last exposure. Guidelines for quarantining and symptoms of COVID-19 are reviewed with each contact. Recently, PHHS announced that they need to curtail contact tracing due to the overwhelming burden of cases and are now providing detailed guidelines to instruct cases to manage their own close contact notifications.⁹

PHHS also specifically recommends that close contacts wait until at least five days post-exposure before undergoing COVID-19 testing. This recommendation was partly based on local availability of PPE and testing, as well as on studies that suggest that false negative rates drop substantially five to nine days after exposure.¹⁰ Testing too early consumes limited testing resources, and risks giving individuals a false sense of security (when they get a negative result while still presymptomatic).

For PUIs in isolation, the timing is different. Individuals who test positive are instructed to isolate until they meet the criteria for being non-infectious (ten days after testing positive for asymptomatic individuals; ten days after symptom onset for symptomatic individuals, provided that symptoms have improved and the individual is afebrile for 24 hours without the use of antipyretics).¹¹ If a previously asymptomatic patient becomes symptomatic, the clock “restarts” for the ten days of isolation, based on date of symptom onset.

Pitfalls of Contact Tracing

When colleges and universities opened this fall, thousands of students returned to college towns from around the nation and even abroad, predictably increasing the risk of exposure to local communities. Contact tracing has been focused on preventing campus transmission from spreading to high-risk populations and congregate living conditions (such as nursing homes or prisons). However, campus-based contact tracing becomes very challenging if students gather in large social groups and are unable to identify close contacts. Following an early surge in cases, our policies, contact tracing and isolation and quarantine protocols successfully maintained a flattened curve throughout the 2020 Fall Semester.¹²

Local communities also face increased risks in grade schools and daycare facilities. There is a necessary balance between the educational imperatives of in-person schooling (including socialization and educational needs of our children) and the public health interest of minimizing the spread of communicable diseases. The optimal balance for each community requires careful weighing of risks and benefits.

A rapid increase in cases can overwhelm a community’s ability to conduct effective contact tracing in a timely manner; lags in notifications and subsequent delays in quarantine of contacts may also result in additional spread. In Boone County, as of January 8, 2021, we have more than 19,000 cases (869 active, 29 hospitalized, 60 deaths), with a total of 108 hospitalized COVID-positive patients in our three hospital systems, because of patients from our neighboring counties. Our positivity rate has increased dramatically, from 2–3% in early June, to over 30% since Thanks giving.^6,8,13 In Boone County, PHHS and the University of Missouri (MU) have tried to ensure that we have adequate resources to effectively respond to increased cases. As of the date of this submission, MU remains able to maintain standard case investigation and contact tracing, while PHHS is now overwhelmed and will rely on cases to manage their own contacts. While this is suboptimal, it is occurring nationally amid the predictable surge in cases this winter. Contact tracing involves many questions and considerations of various scenarios from cases and contacts alike. Health care providers need to be prepared to respond, stay up-to-date with the latest guidelines, and coordinate with county health departments as much as possible.

With the rising number of cases nationally, individuals often see their physicians before being contacted by local health departments. Under these circumstances, providers should inform patients that the health department will contact them with specific recommendations. Meanwhile, the major messages for newly-positive COVID-19 patients are (1) go to the emergency department for any severe symptoms, (2) isolate (i.e. do not share bathrooms or contact surfaces; have someone bring you food if you are in a household with others; do not travel anywhere, including to the grocery store) for at least 10 days after symptom onset (or after a positive test), and (3) list and notify close contacts, defined as those who have been within six feet of a COVID-positive patient for at least 15 minutes during their infectious period (starting two days prior to symptom onset, or two days prior to testing positive if asymptomatic).

Concerns with Contact Tracing Efforts in Relation to Reopening of Schools and Universities in Spring 2021

Emphasizing the role of young people in spreading COVID-19 has also led to unfortunate and inappropriate stigma. We are now in a time of widespread community transmission, and half of COVID-positive patients are uncertain how they acquired the virus.

Stigmatization may result in students and young adults resisting testing or minimizing symptoms to themselves and others. Local authorities need to maintain a caring attitude with students and young adults, while also maintaining a consistent message and clear boundaries for social distancing and masking.

Respecting privacy is another critical concern. Resistance to reporting symptoms can result in missing and inaccurate data, as well as missed opportunities to prevent transmission. In some areas, phone applications have decreased the human resource burden and inaccuracy of contact tracing. Such applications track potential exposure and automatically notify individuals at risk; while these applications show some promise, there are concerns about privacy and effective implementation of such technologies.^13–17

Conclusion

This pandemic has led to unprecedented challenges for our often-neglected public health system. While health departments across the nation have committed thousands of person-hours to PUI investigations and contact tracing, many are overwhelmed by the current rise in cases. Controlling the spread of COVID-19 is extremely labor intensive and requires funding, active community and health care provider engagement, and public recognition and acceptance of the importance of quarantine and isolation. Without these elements, the morbidity and mortality rates for COVID-19 will continue to rise.

Frequently-evolving guidelines are also a challenge to communicate, especially when patients, friends, and family members come to us for answers. As we all grapple with caution fatigue and COVID fatigue, it is incumbent on all of us to follow public health recommendations including the avoidance of large gatherings, regular hand-washing, and maintaining at least six feet of distance from everyone outside of our households, whether or not we are wearing a mask. Nonpharmaceutical interventions, including good cough and hand hygiene, staying home while sick, social and physical distancing, mask-wearing in public, and contact tracing with isolation of positive patients and quarantine of close contacts is still our best bet until we have widespread availability and acceptance of effective vaccines.