Expert Commentary

Digital contact tracing and the coronavirus pandemic: 5 studies to know

Until there’s a vaccine for the new coronavirus, infectious disease professionals worldwide are turning to digital contact tracing tools to help stem the spread of COVID-19.

(Markus Winkler / Unsplash)

Until there’s a vaccine for the new coronavirus, infectious disease professionals point to digital contact tracing as a key way for authorities to safely lift lockdowns and begin cauterizing the economic, mental health and other personal trauma the pandemic is inflicting on millions of people worldwide.

Contact tracing involves monitoring people who’ve come into close contact with those diagnosed with an infectious disease, such as COVID-19. Contact tracing comes in two basic flavors: manual and digital. Health authorities may use them in tandem. Manual contact tracing usually starts with a public health official calling those close contacts and offering recommendations for preventing the virus from spreading further.

“It’s test, track, trace and quarantine,” said Howard Bauchner, editor-in-chief of the Journal of the American Medical Association, on a recent JAMA podcast.

Governments around the world, including in the U.S., are turning to digital contact tracing to speed up the process. Some digital contact tracing applications that epidemiologists and software engineers have developed alert users in near real-time if they have come into contact with someone who has COVID-19. The two primary purposes of using digital contact tracing are case management and proximity tracking, according to the U.S. Centers for Disease Control and Prevention.

Online applications would let people who suspect they have COVID-19 to report symptoms and allow public health agencies to quickly follow up with patients who have been diagnosed. A smartphone application might use geo-positioning data to alert users if they are near someone with COVID-19. Some Americans might be willing to use contact tracing applications, but others may have privacy concerns.

The push-and-pull between ensuring patient privacy and protecting public health is still playing out. Americans are about evenly divided on whether they think it’s acceptable for the government to use cellphones to track people who have contracted COVID-19, according to a recent survey from researchers at Northeastern University, the Harvard Kennedy School and Rutgers University.

“An app that provides fantastic provable privacy but doesn’t help stop the spread of the disease isn’t a useful tool,” wrote Ian levy in a recent blog post from the National Cyber Security Centre, an agency of the United Kingdom government. Levy is the agency’s technical director.

Some estimates put the financial burden of national, digital contact tracing at a small fraction of the cost of recent economic relief bills President Donald Trump signed in recent weeks. Infectious disease specialists Rochelle Walensky at Massachusetts General Hospital and Carlos del Rio at the Emory University School of Medicine estimated the dollar cost of widespread testing and tracing in the U.S. in an April 17 Viewpoint article in JAMA. Viewpoint articles offer scholarly perspectives on current health topics.

It could cost $2.5 billion to do antibody testing on half the U.S. adult population and another $1 billion for frequent testing for people diagnosed with COVID-19, Walensky and del Rio explain. Digital contact tracing could cost $1 billion to $2 billion.

“These estimates suggest that more than $5 billion in public health investment will be required, calculations that exclude the costs of protecting the most vulnerable communities or the investment in research and development required to deliver life-saving diagnostics, therapeutics, and vaccines,” Walensky and del Rio write. “Nevertheless, this investment pales in comparison to the exponentially more profound losses from economic shutdowns.”

The five academic studies that follow offer insights on successful digital contact tracing programs around the world, privacy considerations for digital tracing and more.


Contact Tracing Assessment of COVID-19 Transmission Dynamics in Taiwan and Risk at Different Exposure Periods Before and After Symptom Onset

Hao-Yuan Cheng; et. al. JAMA, May 2020.

The authors are government or university epidemiologists and public health experts in Taiwan, which had its first confirmed COVID-19 case on January 21.

“With proactive containment efforts and comprehensive contact tracing, the number of COVID-19 cases remained low, as compared with other countries that had widespread outbreaks,” they write.

The researchers looked at data from the first 100 confirmed cases in Taiwan, and 2,761 people who had close contact with members of that initial group. They followed up with those close contacts for two weeks after they were last exposed to someone with COVID-19. The researchers defined a “close contact” as someone not wearing personal protective equipment who had face-to-face contact for more than 15 minutes with a COVID-positive person. The Taiwan Centers for Disease Control used an electronic system for case management, “to follow and record the daily health status of those quarantined contacts,” the authors write.

The illness rate was 1% for people exposed within the first five days that the COVID-19 patient started experiencing symptoms. The illness rate was 0.7% for people exposed before the COVID-19 patient began showing symptoms. None of the contacts exposed after that initial 5-day symptomatic period contracted coronavirus.

“These findings underscore the pressing public health need for accurate and comprehensive contact tracing and testing,” writes JAMA Editor-at-Large Robert Steinbrook in an editor’s note. “Testing only those people who are symptomatic will miss many infections and render contact tracing less effective.”


Rapid Implementation of Mobile Technology for Real-Time Epidemiology of COVID-19

David Drew, et. al. Science, May 2020.

The authors discuss early results from the COVID-19 Symptom Tracker smartphone application, which they developed as part of a global consortium of scientists with big data expertise. David Drew is a biomedical researcher at Massachusetts General Hospital. All the authors are epidemiologists or immunologists at top hospitals and research universities in the U.S. and U.K.

The application launched in the U.K. on March 24 and in the U.S. on March 29. By May 2, it had a combined nearly 3 million users. Data gathered through the app offer new insights on how the coronavirus spreads.

Cough and fatigue alone, for example, did not appear to be strongly linked to positive COVID-19 tests. No one who reported diarrhea alone tested positive. Anosmia — the loss of sense of smell — was more common than fever in people with positive tests. The data were also useful in predicting outbreaks.

“In Southern Wales in the United Kingdom, users reported symptoms that predicted, five to seven days in advance, two spikes in the number of individuals reported by public health authorities to be confirmed with COVID,” the authors write.

The authors note several tradeoffs. People with smartphones aren’t representative of a country as a whole. That’s a limitation of any voluntary application, the authors write. The benefit is that the application was deployed quickly and provided useable data. The application is endorsed by national health agencies in the U.K., and the team provides daily updates to the U.K.’s chief scientific officer.

“We are working to develop a similar approach in the U.S.,” the authors write. “However, the lack of a national healthcare system has required a strategy focused on engaging local public health leaders. For example, we have partnered with the University of Texas School of Public Health to conduct state-wide surveillance to support public health decision making, especially as their state government begins softening mitigation strategies.”


Peer-to-Peer Contact Tracing: Development of a Privacy-Preserving Smartphone App

Tyler Yasaka, Brandon Lehrich and Ronald Sahyouni. Journal of Medical Internet Research MHealth and UHealth, April 2020.

The authors developed a proof-of-concept smartphone and web app that allows users to check their potential exposure to the new coronavirus, and anonymously report if they contract COVID-19.

Tyler Yasaka is a software engineer. Brandon Lehrich and Ronald Sahyouni are biomedical engineers. All are affiliated with the University of California, Irvine.

Privacy is central to the application because digital contact tracing doesn’t work without widespread adoption, and people are less likely to use an application they don’t trust. Existing contact tracing apps often rely on personal data, like timestamped location tracking.

“If a sufficiently large portion of a population does not participate due to privacy concerns, such an intervention may have limited impact on the outcome of a pandemic,” write Yasaka, Lehrich and Sahyouni.

Their application works through checkpoints that users, including business owners and public officials, create. People use their smartphones to scan quick response codes posted at places like public parks. The application tracks the checkpoints that users create and join, but doesn’t continually track their location.

When users join a checkpoint, they find out their coronavirus risk status based on confirmed COVID-19 cases from other users who checked in there. To avoid false positives, health professionals could have QR codes that patients would scan to confirm they tested positive for COVID-19. People who contract COVID-19 could share their checkpoint history with their doctors.

“To facilitate contact points for larger numbers of people, local businesses could allow customers to join a contact point by scanning a QR code upon entry,” the authors write. “However, users may become fatigued from such behavior over time and choose to discontinue or may be dissuaded from participating at the onset. Under normal circumstances, these hurdles might deter most users; however, due to the tremendous impact of a pandemic, users may be motivated to overlook these inconveniences in light of alternative, more invasive location-tracking measures.”


Quantifying SARS-CoV-2 Transmission Suggests Epidemic Control with Digital Contact Tracing

Luca Ferretti, et. al. Science, March 2020.

“Given the infectiousness of [COVID-19] and the high proportion of transmissions from pre-symptomatic individuals, controlling the epidemic by manual contact tracing is infeasible,” writes Luca Ferretti and his co-authors. Ferretti is a senior researcher in statistical genetics and pathogen dynamics at the University of Oxford.

The authors propose an algorithm that allows a smartphone app to conduct contact tracing and make isolation recommendations. The application could almost instantly perform contact tracing that would otherwise take a week to do manually, according to the authors.

Positive coronavirus results are transmitted to a central server, with recommendations for self-quarantine or physical distancing for people known to have come in contact with someone confirmed to have COVID-19. Users would know in near real-time if they have been in close quarters with a COVID-19-positive person. People with symptoms could also request tests through the app.

“People should be democratically entitled to decide whether to adopt this platform,” the authors write. “The intention is not to impose the technology as a permanent change to society, but we believe that under these pandemic circumstances it is necessary and justified to protect public health.”


Full Disclosure: How Smartphones Enhance Consumer Self-Disclosure

Shiri Melumad and Robert Meyer. Journal of Marketing, March 2020.

People are more likely to give up personal information when the ask comes from their smartphone rather than their personal computer, according to three field studies and two controlled experiments the authors performed. Shiri Melumad and Robert Meyer are marketing professors at the University of Pennsylvania.

Their analyses included about 10,000 online restaurant reviews, about half written on computers and the other half on smartphones. The authors looked at language reviewers used, such as first-person pronouns, as an indicator of self-disclosure. In another part of the analysis, the authors randomly assigned 715 participants to write about an upsetting personal experience on a computer or smartphone. The authors also reviewed the level of self-disclosure in nearly 300,000 tweets, about 60% of them written on smartphones.

Melumad and Meyer conclude that “increased willingness to self-disclose on one’s smartphone arises from the psychological effects of two distinguishing properties of the device: (1) feelings of comfort that many associate with their smartphone and (2) a tendency to narrowly focus attention on the disclosure task at hand due to the relative difficulty of generating content on the smaller device.”

Check out our other coronavirus-related resources, including tips on covering biomedical research preprints and a roundup of research that looks at how infectious disease outbreaks affect people’s mental health. Also, don’t miss our feature on rural broadband in the time of coronavirus.

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