What is Contact Tracing?
An overview of contact tracing methods and how technology is helping combat COVID-19
By Ryan Mathura, B.S.—Health Science
Mr. Mathura is pursuing his Master of Public Health degree from Emory University in Atlanta, GA, USA. This summer, he is also working as a COVID-19 contact tracing intern for the Georgia Department of Public Health.
Without a vaccine for COVID-19, effectively slowing the spread of the disease requires major changes in our everyday lives. Health departments and ministries all over the world have recommended closing businesses, prohibiting large gatherings of people, working from home, and wearing masks as ways to slow disease transmission. Despite these non-pharmaceutical interventions that are needed due to lack of drug treatments, many people cannot or will not follow recommendations for several reasons.
So, the question is: How do we improve non-pharmaceutical interventions to effectively reach people that are at risk of infection?
Answer: contact tracing!
Figure 1. Why Timing Matters with Contact Tracing. This infographic shows the benefits of isolating individuals who have been in contact with known infected people
Contact tracing is the method of finding and informing people who have been in contact with others who are infected or suspected of infection. At its core, contact tracing requires collecting contact information from infected people about other people they have interacted with during their infectious period. For COVID-19, people are the most infectious as early as two days before symptoms appear [1]. The U.S. CDC recommends that people with COVID-19 self-isolate for at least 10 days after symptom onset with resolution of fever for at least 24 hours. Those who never develop symptoms should isolate for 10 days after their first positive COVID-19 PCR test.
Common steps in the contact tracing process are:
Gather identities of people who test positive for the COVID-19
Conduct interview with infected individuals
Infected individuals are told to isolate until they are no longer infectious
Gather information about people the infected individual has interacted with since his/her infectious period began. Commonly collected information includes the name of the person she/he interacted with, the relationship between the individuals, contact information for the person, and the location and duration of the interaction
Conduct interview with contacts
Contacts are asked to quarantine for up to 2 weeks after interaction
Contacts are given information about best practices and any resources they may need during their quarantine period
Contacts are advised to get tested for COVID-19
Contacts should report their status to public health officials every day until their quarantine period is over
Contacts of the contacts are also recorded
The major benefit of contact tracing is letting people know they are potentially infected. From the moment that an individual knows he or she may be infected, he or she has the power to stop the spread of the virus in its tracks. Unfortunately, many people find it difficult to adhere to quarantine rules while still meeting daily needs. Contact tracing organizations therefore must supply resources such as how to get food and supplies safely while maintaining strict isolation.
Below are two graphics showing the potential impact of contact tracing. Those familiar with the epidemiological benefits of immunizations can make comparisons to the idea of herd immunity. Containing the disease to a few individuals helps protect communities and those who are at potentially higher risk than others.
Figure 2. How Contact Tracing Works. This infographic shows that a single person isolating is not sufficient. Their contacts are required to isolate to stop the spread into the community.
Technology companies have taken a lead with contact tracing. Tech giants such as Google and Apple have developed numerous applications for both sides of the equation: contact tracers and contacts. Google has partnered with MTX to create an open-source web application for the management of information regarding COVID-19 patients and their contacts. They have streamlined the interview process with user-friendly guides, making the entire application highly customizable for tracing organizations to make it work best for them. For contacts, the app has made the symptom reporting process very simple as well. After consenting to receive text messages from the organization contacts only have to reply with a “Yes” or “No” once per day while they are in their quarantine phase. The system will automatically unenroll them after their quarantine phase has ended so the contact knows when they can stop quarantining themselves. Those who do not or cannot use the app are still able to report their symptoms via hotline.
Apple and Google have partnered with each other for seamless integration with their services to be used along with Health Departments. As of August 2020, this technology is still in development and has only been deployed in a handful of regions worldwide. The mobile app’s first aim is for people to download the app and report symptoms. If users report any concerning symptoms, they can request to be tested for COVID-19 and their status is updated within the application’s servers. If potentially or confirmed infected persons consent to share their status, the app will use Bluetooth to alert other app users that they have come with someone who may have COVID-19. In addition, the app can alert users retroactively if a contact receives a positive test within about 5 days. While public health and reporting agencies collect personal information from the app, the app developers state that they do not share personally identifying information among users.
Figure 3. Schematic of App-Based COVID-19 Contact Tracing. This schematic from the open-source article by Ferretti et al illustrates how the Google and Apple application can be used to help people know when to isolate after somebody receives a positive test [2].
This type of mobile health app holds promise, but to be successful, about 60% of a population must adopt its use. The Google/MTX and Apple apps are not the only ones on the market, either. When a population uses multiple different apps that do not interface well, the data become difficult to interpret. Singapore, Australia, and South Korea have adopted national apps, but use in the United States remains highly regionalized. Moreover, despite the companies’ assurances that personal information will only be shared with reporting agencies, the use of Bluetooth proximity tracing poses challenges for privacy and the potential for abuse remains. Several apps have already fallen prey to security flaws. Cultural factors and beliefs about privacy versus social responsibility likely play a role in app adoption rates and their subsequent success.
Contact tracing is by no means a new tool. It is one of the many tried and true public health methodologies that have re-entered the public sphere due to the COVID-19 pandemic. Regardless of success or failure, new innovations in contact tracing will continue to evolve and contribute to the pandemic’s ever-growing influence on attitudes towards technology.
Mr. Mathura has no financial involvement or interest in the Bio Africa Marketplace or products mentioned therein or elsewhere within the BioAfrica Innovation Hub websites. His role in the Scientific Resource Hub does not constitute endorsement or recommendation of specific products or suppliers mentioned within the Bio Africa Innovation Hub websites.
References
Publicly available websites and news articles are linked in the text. Full references for peer-reviewed articles or other sites not publicly accessible are available below.
1. He, X., et al., Temporal dynamics in viral shedding and transmissibility of COVID-19. Nat Med, 2020. 26(5): p. 672-675.
2. Ferretti, L., et al., Quantifying SARS-CoV-2 transmission suggests epidemic control with digital contact tracing. Science, 2020: p. eabb6936.