CDC Study Raises Questions About Agency’s Insulation Guidelines


Five to nine days after first testing positive for coronavirus or developing Covid-19 symptoms, more than half of people who have rapid antigen testing test positive for the antigen test, according to a new study From the Centers for Disease Control and Prevention.

Finding raises more concern agency’s revised isolation guidelinesSaying that many people with Covid can end their isolation period after five days without a negative coronavirus test.

A CDC scientist who is the study’s author said he doesn’t believe the agency’s isolation guidelines need to change. But the scientists said the results show that many people with the virus may still be contagious during this period.

Angela Rasmussen, a virologist with the University of Saskatchewan’s Vaccine and Infectious Diseases Organization, said in an email that the study “shows what many people suspect: five days is insufficient for a significant number of people.” “The bottom line is,” she added, “that this should definitely lead to a change in isolation guidance.”

The research was done after Omicron became the dominant variant in the United States and as cases increased nationwide. cases has fallen rapidly since thenreducing the risk of infection and the number of Americans in isolation.

The CDC shortened the isolation period from 10 to five days in December as the Omicron variant spread. Many public health experts criticized the movementHe noted that people may still be contagious five days later, and allowing them to end isolation without testing could help the new variant spread more quickly.

D., a medical epidemiologist at the CDC and author of the new study. Ian Plumb said he believes the study “fundamentally supports” the agency’s current isolation guidance, which asks people to continue taking precautions, including wearing masks and avoiding travel. — Until 10 full days have passed.

“Honestly, I don’t think that means that current guidance needs to change,” he said.

Instead, he said, the study supports the idea that antigen tests can be successfully integrated into isolation guidelines.

“I think the biggest takeaway is that it’s possible to include antigen tests in the isolation guide because they provide additional information about the risk of someone being potentially infectious,” he said.

The new study was based on people who reported coronavirus infections between January 1 and February 9 to the Yukon-Kuskokwim Health Corporation, which provides healthcare to rural communities in southwestern Alaska.

In early January, Yukon-Kuskokwim published new isolation guidelines. He recommends that people isolate for 10 full days after testing positive for the virus or developing symptoms of the virus. However, individuals with no or no symptoms and no fever for at least 24 hours on days 5 to 9 of their isolation period were eligible for free Abbott BinaxNOW rapid antigen tests administered by Yukon-Kuskokwim staff. If they test negative, they may end their isolation period early.

54.3 percent of 729 people who had an antigen test on the 5th to 9th days of their isolation period were positive. The proportion of people who tested positive decreased over time: 67.5 percent tested positive on Day 5 of their isolation period, compared with 38.6 percent on Day 9.

The researchers found that people with symptomatic infections were more likely to test positive on days 5 to 9 than those who were asymptomatic. People who had received the primary vaccine series (two doses of mRNA vaccine or a single dose of Johnson & Johnson vaccine) or had been previously infected with the virus were less likely to have positive antigen results during this time than those who did not. vaccinated or previously infected.

“Ultimately, I don’t think this is surprising, based on the data we’ve seen and the general concern of the infectious disease community about shortening isolation in the face of a new variant,” said Saskia Popescu, infectious disease epidemiologist at George’s. Masonic University. “But I think it’s important that we continue to evaluate this, as antigen tests are not a perfect proxy for infectivity and ability to transmit the virus.”

The findings are consistent with several other recent studies that have not yet been published in scientific journals or reviewed by outside experts. In one, the researchers found: More than 40 percent of vaccinated healthcare workers positive in rapid antigen tests on days 5 to 10 of their illness.

Inside two other studies, researchers found A significant proportion of people with suspected and confirmed Omicron infections still have high viral loads more than five days after first testing positive for the virus.



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