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New guideline of U.S. CDC to shorten isolation period spurs concerns among experts


The guidance does not require a negative test to leave isolation or quarantine, which experts worry may drive up transmission and new cases. Another concern voiced by epidemiologists is that it fails to distinguish between vaccinated and unvaccinated people.

The U.S. Centers for Disease Control and Prevention (CDC) has shortened isolation time for Americans infected with COVID-19 from 10 to 5 days, which has prompted public confusion and made health experts warn that the recommendation may lead to more COVID-19 spread and more infections cases.

In a new guideline released earlier this week, the CDC is shortening the recommended time for isolation from 10 days for people with COVID-19 to 5 days, if asymptomatic, followed by 5 days of wearing a mask when around others.

The CDC has also updated its recommendation of quarantine period for those exposed to COVID-19. For people who are unvaccinated or are more than six months out from their second mRNA dose or more than 2 months after the Johnson & Johnson vaccine, and not yet boosted, CDC recommends quarantine for 5 days followed by strict mask use for an additional 5 days.

The change in guidance was "motivated by science demonstrating that the majority of SARS-CoV-2 transmission occurs early in the course of illness," according to the CDC.

People line up to pick up free at-home COVID Antigen test kits in Washington D.C., the United States on Dec. 22, 2021. (Photo by Ting Shen/Xinhua)

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CDC Director Rochelle Walensky said the change was also motivated by economic and societal concerns.

"With a really large anticipated number of cases from Omicron, we also want to make sure we can keep the critical functions of society open and operating," she said on Tuesday. "We can't take science in a vacuum. We have to put science in the context of how it can be implemented in a functional society."

The guidance does not require a negative test to leave isolation or quarantine, which experts worry may drive up transmission and new cases.

"CDC's new guidance to drop isolation of positives to 5 days without a negative test is reckless," tweeted Michael Mina, assistant professor of epidemiology at Harvard T. H. Chan School of Public Health.

"Some people stay infectious 3 days, some 12 (days)," he tweeted. "Test negative to leave isolation early is just smart."

With the surge in cases driven by the Omicron variant, the administration of President Joe Biden has faced criticism for failing to prepare adequate supply of tests. People are queueing up at malls and around city blocks, sometimes for hours, to get tested.

Another concern voiced by epidemiologists is that the new recommendation fails to distinguish between vaccinated and unvaccinated people, who recover from the virus at different times.

"Vaccinated people are much less likely to get infected and less likely to be infectious for a long period of time," said Aaron Caroll, a pediatrician at Indiana University.

Eric Topol, director of the Scripps Research Translational Institute, said the policy represents "a new low" for the CDC, saying it flies in the face of the Biden administration's pledge to hew closely to scientific evidence to curb the pandemic.

Some experts are concerned there is not enough evidence of how Omicron behaves to support CDC's new five-day isolation recommendation.

In the meantime, some other experts acknowledged that shortening the isolation period would relieve stress on hospitals and businesses as more workers become infected with Omicron. 

Published : December 31, 2021

By : Xinhua