Contact tracing: Are we doing enough?

As some states begin to relax Covid-19 lockdown measures, many are questioning whether these states have the resources to open up safely. Along with massive testing and acquiring personal protective equipment and ventilators, another important piece of the puzzle is contact tracing.

What is contact tracing?

Contact tracing is the process of finding people who have been in close contact with an infected person, and providing these contacts with resources they need to avoid spreading the virus. Contact tracing for Covid-19 has received a lot of attention recently, but public health personnel have used contact tracing for decades to stop the spread of viruses such as SARS, Ebola, and HIV.

Currently, contact tracers are working with Covid-19 patients, asking them about everyone they had close contact with while they were infectious. (A close contact is someone who was within six feet of the infected person for more than 15 minutes within at least two days of their positive test.) Contact tracers then reach out to each of those contacts to inform them that they may have been exposed to the virus, and provide them with resources to isolate themselves and monitor their symptoms. To preserve the privacy of Covid-19 patients, contact tracers do not share the identity of the Covid-positive person with potential contacts, only informing contacts that they may have been exposed.

How can contact tracing help prevent Covid-19 spread?

Contact tracing is generally used during the “containment” phase of an epidemic–when the prevalence of infection is low and all cases can be feasibly tracked. In South Korea, Singapore, and Hong Kong, contact tracing–along with extensive testing–has been an important part of flattening the curve in the first wave of the virus.

Some US states have already created contact tracing programs to prevent the spread of the virus and facilitate a safe reopening. For example, Massachusetts has trained more than 1,200 contact tracers and supervisors, who have already contacted more than 17,000 people to trace and contain the virus. Illinois is planning to hire 3,800 contact tracers in coming weeks to stop the spread of Covid-19. New York is going even further, hiring an “army” of up to 17,000 contact tracers.

Will this extensive effort will be enough?

The Fitzhugh Mullan for Health Workforce Equity at George Washington University just released a new tool for estimating the necessary contact tracing workforce in each state. The number of contact tracers needed depends on how many new cases each state is reporting, how many people each infected person comes in contact with, and the daily caseload of each worker.

Currently, Massachusetts, New York, and Illinois still have high numbers of new cases, but because of shelter-in-place orders, people with Covid-19 have fewer close contacts to report. However, even if each person has just two close contacts, Massachusetts still will need about 3,000 contact tracers, at the current rate of new Covid-19 cases. When the number of new cases decrease, contact tracing will become even more effective, but states should keep in mind that when shelter-in-place orders end, the number of contacts will increase, making it harder for tracers to find all of the necessary close contacts.

And what about states that are opening up without a plan for hiring contact tracers? They could be caught off-guard. For example, Colorado will need about 3,000 contact tracers, according to the Mullan Estimator. But so far they only plan on hiring 50 students to help with contact tracing, even though the state started reopening retail businesses on May 1.

A new public health corps

Overall, the Mullan Institute estimates that the country will need nearly 180,000 contact tracers nationwide, given the current rate of new cases. This seems like an overwhelming effort for the country to undertake. However, some see the labor-intensive nature of contact tracing not as an obstacle, but as an opportunity. In The American Prospect, Leif Wellington Haase, former director of the New America California office, argues that the US should create a new “Public Health Corps,” reminiscent of the New Deal’s Civilian Conservation Corps, to train newly unemployed Americans as contact tracers.

More than 30 million Americans are unemployed due to Covid-19 and the subsequent economic fallout. Jobs that people can do from home are in high demand; about 9,000 people applied for a contact tracing position in Massachusetts in the first 24 hours of the job posting. “In addition to being a public-health necessity, contact tracing can serve as a temporary jobs program,” writes Haase.

Some argue that building a large contact tracing workforce is unnecessary; why hire so many people when we could just use a tracing app instead, like the one that Apple and Google are building? The experiences of some countries in using these apps shows that they can be helpful in tracing Covid-19 cases. But experts warn that there are many obstacles to implementing such a system effectively, including low utilization of the app, privacy concerns, and technology errors causing false positives and negatives. For these reasons, technology-based contact tracing should be used to complement, not replace, manual contact tracing.