When Will This REALLY be Over? Part 3b of 4: Contact Tracing

When will we talk about the coronavirus pandemic in the past tense? When can we live as we did in 2019, without fear of COVID-19 cases rising again? In part one of this series, we reviewed three indicators that will tell us when we’re getting close to the end: 1) wait it out until we have global herd immunity, 2) hunt and catch all new cases with testing and tracing, and 3) give our bodies armor and shields against infection using vaccines or other prophylactic treatments. In the last post (part 3a of 4), we discussed the importance of testing and examined the status of viral testing in the United States. We’re back for part 3b of 4 of this series, where we’ll delve into the “catch” part of the “hunt and catch” approach—contact tracing. Testing and contact tracing go hand-in-hand to contain the spread of coronavirus. While testing identifies initial cases of COVID-19, tracing helps catch additional cases that might otherwise remain undetected. This essay will answer these questions:

1) What is contact tracing? 2) Why is contact tracing important? 3) What does a contract tracer do? 4) How might phone apps aid the work of contact tracers? 5) What is the status of contact tracing in the United States today? 6) How can you help support contact tracing efforts? What is contact tracing? In this context, the definition of contact is “a person who has lately been exposed to an infected person.” If a person tests positive in a COVID-19 viral test, the people they have been close enough to pass the virus to are their contacts. Tracing is the term for the investigation that follows a new COVID-19 case confirmation. A contact tracer is a person whose job it is to interview positive confirmed cases. The goal of contact tracing is to find out everywhere an infected person has been and track down the people they were nearby during the time they might have been shedding the SARS-CoV-2 virus. The contacts of positive people are advised to self-quarantine and, if available, get tested. Why is contact tracing important? In the last essay, I explained why a lack of testing limits our ability to control the spread of coronavirus. In an ideal situation, every US citizen would have a dozen COVID-19 viral test kits at home they could take whenever they wanted to check themselves. If this were true, everyone could know if they’re positive or negative. People with a positive result would presumably stay away from other people. While people with a recent negative test result could go out knowing the chance they are positive is relatively low (but not zero). Even people who get a negative test result should still behave as if they might be infected because testing is not perfect. People can actually be positive (infected) but score negative because they have low levels of virus. This can happen if they recently got infected and the virus has not multiplied in their body enough yet to be detected by the test. Contact tracing is critical to slowing the pandemic because it helps us find additional COVID-19 cases among people who are unlikely to take a viral test. It is essential to identify positive cases before they feel sick or early in their infection, before they spread the virus to others. Let’s revisit an analogy introduced in part one of this series to explain further why contact tracing is important. Pretend you protect a vast forest and the people who live there from wildfires. One way to do that is to employ a group of people who vigilantly hunt for little fires. When they find a small fire, their job is to put it out and make sure it does not spread to nearby trees. The first hint that a new fire is brewing might be the sight or smell of smoke. This is like when a viral test comes up positive, identifying a new COVID-19 case. The contract tracer is like the forest staff; they race to the site of the fire and circle it, trying to stop further spread. Contact tracing snuffs out tiny COVID-19 local outbreaks before they can grow into large outbreaks. What does a contract tracer do? Next, I’ll be referring to this illustration to explain how a contact tracer does their job. Let’s start with the confirmed case person in red with a “+” on their head. They just received a positive test result verifying their infection by the SARS-CoV-2 virus.

A contact tracer is assigned to investigate the infected person. The interviewer must figure out when the person first felt sick (or note if they have not had symptoms) and when they took their test. They use this information to calculate when the person probably became contagious and when their infection should be over. Next, the contact tracer questions the person about where they have been during their infectious period. They record the people they’ve been closer than six feet from for over 15 minutes. A person could get infected from one direct sneeze in an instant; the 15-minute limit is arbitrary. However, this limit helps a tracer prioritize finding the contacts who are at greatest risk of exposure. In the illustration above, there are five lines to other people who the contact tracer discovered might have been exposed. The contact tracer then notifies each person to warn them they have been near a person who tested positive. The tracer does not share the name of the infected person to maintain their privacy. If there is testing available, the tracer will test all five people. Regardless of testing, though, the tracer will urge the contacts to act as if they are positive and self-quarantine for 14 days, just in case. In this example, let’s assume that testing was not available for these contacts. However, all five people agreed to stay home and away from others. The tracer would check in with each of these contacts daily to ask them about their symptoms. One contact (the orange figure), reports a fever and illness. This person is labeled as a probable COVID-19 case because they have disease symptoms and known recent contact with an infectious confirmed case. In the example illustrated, the probable case has contacted five additional people (beyond the confirmed case). Next, the contact tracer would interview the contacts of the probable case. They follow a web of clues, investigating people and their interactions, to hunt down everyone who might be positive. When people have many contacts, and several of the contacts also test positive, the role of contact tracer is labor intensive. Another factor complicating the role of contact tracer is their need to protect themselves from getting the virus. For COVID-19 tracing, most of the work is by phone or email. Sometimes, however, a tracer has to knock on a door. They do this with proper PPE (personal protective equipment). How might phone apps aid the work of contact tracers? If someone with COVID-19 visited a crowded public place, such as a bar, they might not know the names of the people they sat next to for hours. When this happens, the contact tracer wouldn’t be able to find those people, but a phone app could! When Bluetooth is on, phones notice when other phones are nearby. This information could be stored for a few weeks and used to alert anyone who had a phone that was near the phone of an infected person. Smartphone technology has been used in other countries as a tool in the hunt and catch strategy and might be deployed in the United States soon. A well-designed cell phone app would help people avoid locations with more COVID-19 as well as assist tracers’ efforts to find contacts. It can only work, though, if widely used by a majority of Americans. That’s why Apple and Google are doing something uncharacteristic—they are collaborating on this project! Take another look at the illustration; focus on the purple cell phones and dotted lines connecting the phones. This app would use Bluetooth location to show the location of positive cases and places where infectious people have been recently. The app might collect data from people who have tested positive and choose to self-identify. Or they might have people report symptoms of illness, regardless of whether testing has verified it.

The purple figure in the top left has not had contact with the others in the picture. They are looking at their phone to visualize their risk of contracting the virus in their location. The individual is using the app to inform their decision about where to go. App users might view a map showing where positive cases have been reported near them lately. This could help everyone move about with less risk. Contact tracing with viral testing (possibly with a cell phone app technology) creates an effective strategy to reduce the spread of COVID-19. This could empower people to be safer when they are being social, informed by real-time knowledge of their local situation. Experts agree this approach is important, especially once stay-at-home restrictions are lifted. Next, let’s look at what the United States is doing to deploy this strategy. What is the status of contact tracing in the United States today? The United States has always had contact tracers. This is not a novel idea; contact tracing is a fundamental tactic used to control many infectious diseases. Pre-pandemic tracers typically worked on sexually transmitted and other infectious diseases. Historically, the United States used less than 10,000 contact tracers. As a result of this pandemic, though, local, state, and federal public health organizations are increasing staff. As of April, (add link) when the current open positions are filled, there will be nearly 40,000 tracers to work on COVID-19. Experts who have been studying COVID-19 contact tracing programs in other countries, combined with an assessment of the current situation in the United States agree, however, we need over 40,000. John Hopkins and Harvard groups recommend a minimum of 100,000 tracers. A recent bipartisan letter to congress requests federal funding to bring our tracer levels up to 180,000 people. The "Box it In" strategy proposed by Resolve to Save Lives (an organization led by former CDC director, Dr. Tom Frieden) warns that if our COVID-19 cases continue to increase, we may need closer to 300,000 tracers. The number of contact tracers we need will change. The greater the number of local outbreaks, the more tracers we’ll need. As explained in the last post, we cannot test our population widely. Therefore, no one knows for sure how many COVID-19 positive cases there are at any moment and where, precisely, they are located. The range in estimates for tracer needs differs because they are based on different views of the actual numbers and geographic distribution of COVID-19 cases. As our testing capabilities increase, however, the data will become more accurate, and our needs for contact tracing will become more clear. The experts agree we need more tracers, but they disagree on how and when. There is debate over who will pay the wages of the extra staff. Experts also differ on the qualifications needed for new hires (e.g., whether a degree or relevant experience should be required). There is also disagreement on the timing trade-off between ramping up our testing-and-tracing approach versus relaxation of curve-flattening social restrictions (masks, social distancing, travel, group-size, etc.). The job contact tracers face becomes more difficult if everyone goes out and mingles together. If we had over 100,000 tracers working before lifting stay-at-home orders, they would be better able to control the spread. However, that may not be practical. If the rise in cases is sudden and widespread post-relaxation of restrictions, the contact tracers (regardless of how many we hire) might become overwhelmed, rendering this approach ineffective. Therefore, this is why many are clamoring for immediate drastic increases in content tracing and testing. How can you help support contact tracing efforts? First, regardless of the official rules in your area, if you can do so safely and without harming your livelihood or mental health, you can help others if you minimize the number of people or places you visit. If someone you know tests positive for infection with COVID-19 and a contact tracer calls you, their job will be easier if you only have to report contact with five people and five places, compared to 25 of each! You can also help by answering your phone or replying to contact tracers. Many of us screen calls for spam and don’t answer our phones or check emails from people we don’t already know. If you are exposed to a person with COVID-19, the tracer needs to reach you. Take the call. Answer the email. Help the tracer find you. If you have the skills to be a contact tracer and if you are looking for employment, you could apply for this job. If interested, contact your local or state health department to find out if they are hiring tracers. If funding is not available, some regions might accept volunteer contact tracers. To be a competent contact tracer, you have to be comfortable talking to people and be patient and kind. You would have to be able to interview people, keep accurate records, and help people feel comfortable sharing where they’ve been and who they have been around recently. You can also help by using the COVID-19 phone app when it is released. It will only work if most people who have smartphones use it. Otherwise, it won’t have enough data to provide accurate information. Encourage your friends and family to use the app too. This concludes today’s discussion about the importance of contact tracing, an important job, and part of a productive hunt and catch strategy, which will help us contain COVID-19 cases. See you soon for the last segment of this series aboutCOVID-19 vaccines and prophylactic treatments. Take care, COVID Carrie