“Contact tracing is useful because it allows us to help people at direct risk of infection, rather than only being able to act in ways that help the whole community, which helps us use broad actions like shelter-in-place more sparingly, and also ensures that we can direct our time and attention to where they’re needed most.”

Eric Lofgren MSPH, PhD, Assistant Professor, Paul G. Allen School for Global Animal Health, Washington State University 

“The benefits of contact tracing are, if done correctly, it is a thorough process that helps identify and quarantine exposed individuals so they cannot then transmit the virus to others; it breaks the chains of transmission.”

Diana Cervantes, MS, DrPH, CPH, CIC, Assistant Professor at the University of North Texas Health Science Center at Fort Worth, Department of Biostatistics and Epidemiology and Director of the MPH Epidemiology Program

“Contact tracing is useful for a few purposes: treating people that may have been exposed, preventing new chains of transmission, identifying the degree of risk to people exposed to the case. For jurisdictions in the U.S. that have relatively few cases (now or in the future), contact tracing can be a very effective way to get people tested and isolated if they have been exposed to an infectious case, thereby limiting transmission. Contact tracing is most useful in the early stages of an outbreak, since the number of potential cases is small, and the outbreak may still be prevented or contained. With collective effort we may return to the point where each new case can be investigated as a local outbreak that can be prevented.”

Neil Abernethy, PhD, Associate Professor of Biomedical Informatics and Medical Education, University of Washingto

“Contact tracing is an old public health approach used particularly for TB and selected STDs, to identify individuals who may have been exposed and who may be incubating the infection and require treatment. As practiced in the past, it is labor intensive and requires substantial training of the those acting as contact tracers.”

Arthur Reingold, MD, Professor of Epidemiology; Head, Division of Epidemiology and Biostatistics, School of Public Health, University of California, Berkeley

Currently, contact tracing is a manual, very labor-intensive process involving public health staff, such as epidemiologists, calling individuals to obtain information. Per the World Health Organization, contact tracing involves detecting cases to identify their contacts; obtaining information and providing information to these contacts about the disease and their next steps due to their exposure; and, lastly, following up with contacts to determine if they develop signs and symptoms.

Diana Cervantes, MS, DrPH, CPH, CIC, Assistant Professor at the University of North Texas Health Science Center at Fort Worth, Department of Biostatistics and Epidemiology and Director of the MPH Epidemiology Program

“Contact tracing with Covid-19 is complicated by the low availability of testing, the rapidity of transmission and the likelihood that asymptomatic and pre-symptomatic cases may still transmit the disease. It is further complicated by staffing constraints during a widespread epidemic and the risks to investigators in high-prevalence communities. Another challenge is that this is a new disease – we are still learning about the hallmarks of infectiousness, the type of exposures, and the characteristics (like age or comorbidities) that put people at risk. Finally, the poor and inconsistent funding climate faced by our public health departments is a persistent national embarrassment; many health departments simply cannot afford staffing to conduct contact investigations.”

Neil Abernethy, PhD, Associate Professor of Biomedical Informatics and Medical Education, University of Washington

“For COVID-19, it is almost certain to be the case that, on average, each infected individual whose contacts need to be traced will have more contacts than the average individual with an STD, so the workload will be substantial.”

Arthur Reingold, MD, Professor of Epidemiology; Head, Division of Epidemiology and Biostatistics, School of Public Health, University of California, Berkeley

“Respiratory diseases are always challenging for contact tracing because they can be spread to people you didn’t directly interact with, which makes the number of potential people we have to find much larger, and much harder for people to recall correctly. The long period of time people can be infected with SARS-CoV-2 without knowing they are infected or necessarily showing obvious symptoms makes this doubly challenging, as there’s also a much more vague time period we have to consider where people might have been exposed.”

“There are special challenges with COVID-19 contact tracing due to the incubation period, when a person may have been exposed to the virus, and the infectious period, when a person is infectious and could transmit the virus. A two-week period is a long period of time for people to recall how they may have been exposed. In addition, since a person can transmit the virus before having any symptoms, it makes it difficult for a person to remember who they may have exposed (their contacts). Also, since there are people who may never have signs and symptoms or have very minor signs and symptoms but can spread the virus, these individuals will likely not be identified in contact tracing and so the chains of transmission cannot be broken.”

Diana Cervantes, MS, DrPH, CPH, CIC, Assistant Professor at the University of North Texas Health Science Center at Fort Worth, Department of Biostatistics and Epidemiology and Director of the MPH Epidemiology Program

“Several mobile applications have been proposed to help notify individuals who have come into contact with infectious cases. Other apps might support contact notification in the spirit of partner notification, to help us inform those we may have exposed while also sharing this information with public health authorities. This would be useful in our current circumstances since we don’t have enough trained disease investigators to go around. ”

Neil Abernethy, PhD, Associate Professor of Biomedical Informatics and Medical Education, University of Washington

“First, technology helps facilitate contact tracing by allowing much of it to be done remotely, minimizing direct contact between public health workers and the people they are trying to help. But the use everyone is currently focusing on is the ability to use technology to try and identify people who someone came in contact with, even in locations they don’t remember being, or fleeting contacts they don’t remember having. That helps contact tracing be more thorough, and also helps reduce the strain on some very busy departments of health right now.”

Eric Lofgren MSPH, PhD, Assistant Professor, Paul G. Allen School for Global Animal Health, Washington State University

“As manual contact tracing is so time and labor intensive, current technologies such as using cell phone signals and apps to identify and automate contact tracing may help supplement manual contact tracing efforts.”

Diana Cervantes, MS, DrPH, CPH, CIC, Assistant Professor at the University of North Texas Health Science Center at Fort Worth, Department of Biostatistics and Epidemiology and Director of the MPH Epidemiology Program

“There are absolutely privacy concerns – you’re dealing with both people’s health information, and also data on where they’ve been and who they’ve seen. In order to do contact tracing properly, you have to know a lot about where someone was and who they were with at the time, and doing that on a massive, automated scale is absolutely a situation where a breach of privacy could very seriously impact the people you are trying to help.”

Eric Lofgren MSPH, PhD, Assistant Professor, Paul G. Allen School for Global Animal Health, Washington State University

“Patient privacy is a top priority of public health authorities – there can be no investigations without trust, and therefore people can rely on public health agencies to protect their privacy. However, privacy is also a huge concern in the era of smartphones and digital tracking. Cell providers, marketing companies, and the government all have access to cell phone tower data that can localize mobile devices. This data has been used by some countries to guide their disease investigations. However, there are privacy-preserving approaches such as the Apple/Google partnership using opt-in Bluetooth data. There is a risk that this pandemic becomes a slippery slope that encourages more monitoring of the population for other purposes. Researchers and policy-makers alike should work with the public to identify which conditions are acceptable for the use of such information.”

Neil Abernethy, PhD, Associate Professor of Biomedical Informatics and Medical Education, University of Washington