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On a Tuesday in March, 60 members of a choir in Skagit County, Washington State, gathered for rehearsal. All were feeling well, and the session went as usual. With the COVID-19 outbreak nearby, the singers were careful to avoid physical contact.
Over the next few days, several choir members developed fever and cough. A week later, one of them alerted the county health department, and public health disease detectives quickly went to work.
Starting with the choir roster, they called all 121 members to determine who had attended the practice. Many attendees reported having cough and fever. The public health staff asked each of these to list everyone they had close contact with before and after their symptoms began. Then they called all those people, advising them to quarantine themselves while they were assessed and tested for COVID-19.
Three weeks after the rehearsal, 45 of the 60 singers were ill with COVID-19, three were hospitalized, and two had died. The health officers worked hard to identify everyone who was exposed. Because of their fast, expert and sensitive detective work, they were able to warn the people who had been exposed and protect the community.
The strategy they used is known as contact tracing. Contact tracing is a powerful, tried-and-true service health departments use to stop outbreaks and epidemics of many contagious diseases.
Imagine 45 people developing a contagious disease, each infecting two to three other people, and each of those people infecting two to three more, and this continuing. That outbreak would quickly become a big epidemic. By finding contacts, isolating those with symptoms, and having the rest quarantine for two weeks, a health department can nip a small outbreak in the bud, preventing it from exploding into a full-blown epidemic.
The initial outbreaks of COVID-19 exploded. Extensive physical distancing and sheltering in place have therefore been needed to “flatten the curve.” But all we’re doing now is a strategic retreat – into our homes. We need to come out again, and when we do, it’s inevitable that there will be more spread of the virus.
To be safer, we’ll need to #BoxItIn, with four essential actions: extensive testing to find infected people, effective isolation of all who are infected, contact tracing to warn those exposed, and quarantine of the contacts found.
That’s the only way to keep the epidemic from roaring back. We need to conduct contact tracing on a massive scale: identifying every new case; identifying and locating every contact of every case; testing every contact and checking them for symptoms; isolating those who are ill with COVID-19; and quarantining those who were exposed so that if they become sick they won’t infect other people.
This isn’t about big tech companies using databases of personal information or cellphone records to track people’s whereabouts. It’s person-to-person contact tracing the way it’s been long done by public health workers trained to protect people’s privacy and confidentiality. But it has to be done for every case and contact – because if just one chain of transmission is missed, the virus will get out of the protective box and rage through our communities again.
Each of us has a right to know if our neighborhood is about to be hit by a hurricane. We expect the government, supported by the private sector, to warn us so we can protect ourselves and our families. In the same way, every community throughout the United States needs to strengthen the early warning system for COVID-19 – so you will find out if you’ve been exposed and can take steps to avoid spreading the infection to your loved ones, neighbors, and community. That’s what contact tracing does.
Until we have a safe and effective vaccine, this is the only way we can prevent the epidemic from coming back. Contact tracing is an essential key to a future without COVID-19 epidemics.
It will be a massive effort, requiring thousands of public health workers partnering with community, religious and social service organizations to support patients and their contacts who are in isolation or quarantine. But it’s what we will have to do to prevent many more deaths and to get our lives and economy back on track as soon and as safely as possible.
Dr. Sam Dooley is a medical epidemiologist who retired in January 2020, after 31 years of service at the U.S. Centers for Disease Control and Prevention.