CDC Shortens Isolation for Some Covid Infections

New recommendation comes as Omicron variant has sickened workers, putting stress on some industries

By Julie Wernau and Nidhi Subbaraman

The Wall Street Journal

U.S. officials cut the number of days that they recommend people isolate after being infected with Covid-19 to five days from 10, reflecting recent research, new pandemic-management ideas and stress on some industries as the Omicron variant has sickened workers.

The Centers for Disease Control and Prevention said Monday that people who have been infected with Covid-19 and are asymptomatic may leave isolation after five days and should wear masks around other people for five more days. 

Vaccinated people exposed to someone with Covid-19 should wear a mask around others for 10 days and take a Covid-19 test five days after exposure if possible, the CDC said.

The guidance opens the door for people to more quickly return to work, stores and other public spaces after contracting the coronavirus, a move public health experts say is in line with recent research about how long vaccinated individuals with Covid-19 remain contagious.

Some business leaders and public health experts had called for quarantine and isolation periods to be shortened as the highly infectious Omicron variant drives a surge in cases.

The risk of infection diminishes significantly toward the end of such windows, they said, and long absences for workers have strained operations at hospitals, airlines and other businesses.

The CDC said the change was informed by science demonstrating that the majority of Covid-19 transmission occurs early in the course of illness, generally in one to two days before the onset of symptoms and two to three days after.

Many countries have recorded skyrocketing daily Covid-19 case numbers since Omicron was identified in southern Africa in November. The CDC earlier in December said it had become the dominant variant in the U.S. within weeks.  

The seven-day average of new Covid-19 cases in the U.S. reached 198,405 on Sunday, according to a Wall Street Journal analysis of Johns Hopkins University data, a level last seen in January, amid the biggest pandemic surge to date. Many states haven’t reported new infections on some recent days because of the Christmas holidays.

Early studies in South Africa and the U.K. point to Omicron’s reduced severity in populations with high levels of immunity. People infected with the Omicron variant are between 50% to 70% less likely to be admitted to the hospital than those who were infected with earlier strains, according to a recent U.K. study.

The high number of Omicron cases expected in the U.S. and elsewhere in weeks ahead means that employers and public officials must adjust their recommendations for people who contract the virus, public health experts said. 

“When you have a rapidly spreading infection that’s going to have tens of millions of Americans infected in the next couple of months, 10 days is enormously disruptive,” said Ashish Jha, dean at the Brown University School of Public Health. “This policy is safe, it doesn’t put people at risk. We don’t think most people are contagious after five days.”

It is important that guidelines differ for vaccinated and unvaccinated people because studies have shown that vaccinated people with Covid-19 stay infectious for shorter periods than those who are unvaccinated, said Jay Varma, director of Weill Cornell Medicine’s Center for Pandemic Prevention and Response.

Whether a person shows symptoms is also key. “We know from many, many analyses of Covid outbreaks that people who are symptomatic are far more likely to infect other people than people who are asymptomatic,” Dr. Varma said. 

An eight-month study of breakthrough infections among 173 National Basketball Association participants published earlier in December in the New England Journal of Medicine showed that unvaccinated people were infectious for up to eight days, while vaccinated people cleared infections in under a week. Different variants didn’t cause meaningfully different infection times, the researchers said. The study was conducted before Omicron was identified. 

The coronavirus multiplies in the nose and throat of a person with Covid-19, and escapes in droplets and particles when that person breathes out, according to the CDC. Someone else can pick up the virus if they breathe in those particles for a prolonged period, or if a large enough number of particles reach the eyes, nose or mouth.

The CDC had recommended that people with Covid-19 isolate for 10 days from the first day symptoms develop or from a positive test. The agency on Thursday issued new guidelines for healthcare workers, reducing their recommended isolation time. 

Some workers have said that shorter isolation periods would put them at risk. National Nurses United, the country’s largest union of registered nurses, said in a letter to CDC Director Rochelle Walensky that shorter isolation times would result in more transmission, illness and deaths. 

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