Why implementing contact tracing might be harder than we originally thought

Medical experts are hoping that contact tracing might be the key to getting the coronavirus pandemic under control. The three-pronged system—which involves identifying those who have tested positive for the virus, tracking down anyone who may have come in contact with the infected person, and monitoring those individuals—is nothing new. Contact tracing has been used by global public health departments for decades to contain other diseases such as tuberculosis, HIV, and Ebola outbreaks.

However, it’s much more difficult to use contact tracing to track a respiratory pathogen, as opposed to one that’s transmitted through sex or blood. And the aspects of COVID-19 that make it such a unique virus—namely, the delay between when an individual becomes infected and when that individual starts showing symptoms—also contribute to why contract tracing may be more challenging than initially imagined.

Though challenging, it’s not impossible, as countries such as South Korea and Germany have credited modest outbreaks to early contact tracing.

Currently, the two biggest obstacles preventing successful contact tracing in the United States are the lack of widespread resources (such as testing and trained contact tracers) and the need for public cooperation. When practices as simple as social distancing and wearing a mask in public continue to be such hot-button political statements among many Americans, it’s not hard to imagine some parts of the country flat-out refusing to participate in contact tracing.

Not to mention, successful contact tracing potentially means asking people who have been exposed to quarantine for up to two weeks, which could present a logistical nightmare for those who are unable to isolate themselves from jobs or family.

Marc Lipsitch, an epidemiologist at Harvard’s T.H. Chan School of Public Health, said recently that “it’s clear that you can do a lot of control if you do contact tracing really well,” but he warned that it’s also “easy to overwhelm a relatively constrained group of people,” especially when you take into consideration testing limitations combined with an inundation of cases.

With 20,000 new COVID-19 daily cases being reported as of the end of May, the number of cases severely outnumbers the amount of tracers that have been hired so far. Some experts have suggested that 100,000-300,000 tracers could be needed to get ahead of the virus. “This really is the best tool we have to manage the pandemic until we have a safe and effective vaccine,” said Crystal Watson at the Johns Hopkins Center for Health Security.

And while testing has also ramped up—the U.S., as of early June, was testing up to 400,000 people per day, according to The Atlantic’s COVID Tracking Project—the country is still far off from the ultimate goal of anywhere from 500,000 to several million tests per day needed to make contact tracing truly effective.

Contact tracing in New York City

New York City, which was hit hardest by the coronavirus pandemic, is a microcosm that could serve as an example for the rest of the country if contact tracing eventually proves to be successful. However, there are “enormous challenges in New York City,” according to former CDC director Dr. Tom Frieden, who currently serves as president and CEO of Resolve to Save Lives, a global public health initiative that is working on the state’s contact tracing efforts.

“This is the biggest health emergency in more than a century and New York City has had a heartbreaking number of deaths,” he said, via the Guardian. “All the things that we love about New York City … make it more susceptible and more challenging to do contact tracing.”

In addition to crowded housing situations—such as nursing homes, correctional facilities, and homeless shelters—Frieden says that other challenges include population density, reliance on public transportation, and people traveling into the city. He also admits that contact tracing is “not an easy job” that “requires an understanding of patient confidentiality, medical terms, principles of exposure, infection, and symptoms, as well as interpersonal skills and cultural sensitivity.”

The glimmer of hope is that, while contact tracing clearly faces an uphill battle, it doesn’t need to be a perfect system to make a serious dent in new COVID-19 cases—especially if the immediate goal is to reduce the number of ill patients to the point that hospitals are no longer overwhelmed. According to one modeling study, if health officials can identify even half of all symptomatic cases and trace 40 percent of those contacts, “the ensuing reduction in transmission allows the reopening of economic activities while attaining a manageable impact on the health care system.”

Sources: Atlantic, STAT, Guardian, CIDID

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