The agency had previously recommended that those who have been in close contact with someone who has been infected with the coronavirus immediately enter a quarantine period for fourteen days. The two weeks is based on how long scientists believe it can take the virus to incubate in the body and potentially be spread to others.
The fourteen-day quarantine is still the “best way to reduce the risk of spreading COVID-19,” Dr. Henry Walke, the agency’s coronavirus incident manager, said in a news briefing on Wednesday. But there are now “two acceptable alternatives.”
According to the guidance, quarantine can end after ten days if the individual has not developed any symptoms and seven days if the asymptomatic person also tests negative for the virus.
Walke added that the sample for the negative test should be collected within forty-eight hours of the final day of quarantine.
“We continue to refine our guidance to prevent transmission and protect Americans,” he said. “Reducing the length of quarantine may make it easier for people to follow critical public health action by reducing the economic hardship associated with a longer period, especially if they cannot work during that time.”
The CDC is hoping that the change will boost compliance with one of the most important tools for limiting the spread of the virus, which has reached new heights over the past couple of weeks.
“In a situation where cases are rising, that means that the number of contacts are rising, and the number of people who require quarantine is rising. That’s a lot of burden, not just on the people who have to quarantine, but also on public health,” Walke said.
“We believe that if we can reduce the burden a little bit, accepting that it comes at a small cost, we make greater compliance overall with people.”
CDC scientists and outside researchers calculated that for people ending quarantine after seven days, the “residual post-quarantine transmission risk” is about 5 percent, with an upper limit of 12 percent, according to Dr. John Brooks, the chief medical officer for the CDC’s coronavirus response.
Meanwhile, the risk of transmission drops to about 1 percent for those who quarantine for ten days, with an upper limit of 10 percent.
Last month, the CDC revised its language on what it defines as “close contact” with a coronavirus-positive individual.
Previously, health officials considered close contact to be spending fifteen consecutive minutes within six feet of an infected person. But the definition was changed to being within six feet of an infected individual for a total of fifteen minutes or more over a twenty-four-hour period.
Ethen Kim Lieser is a Minneapolis-based Science and Tech Editor who has held posts at Google, The Korea Herald, Lincoln Journal Star, AsianWeek, and Arirang TV. Follow or contact him on LinkedIn.