The US Food and Drug Administration issued a new recommendation on Thursday that asymptomatic people who are using at-home COVID-19 antigen tests take at least three tests, each spaced 48 hours apart, so that there is no risk of infection. to reduce the chances of missing.
According to the agency, people who have symptoms of Kovid-19 should undergo at least two tests at an interval of 48 hours.
The new guidelines come as Omicron’s highly transmissible ba.5 subvariant continues to circulate, and after the Centers for Disease Control and Prevention relaxed its recommendation for routine surveillance testing in most circumstances.
Many people have reported that at-home tests failed to detect their infection, but studies have generally shown that rapid antigen tests are as good at detecting omicrons as they were at detecting delta , previous ed.
Experts have long noted that rapid antigen tests, which are less sensitive than PCR tests, are designed to be used sequentially, and when people take them repeatedly over the course of several days. then they are most likely to detect the coronavirus.
But the new recommendations emphasize the need for “additional testing over the long term,” the agency said.
Dr. Jeff Shuren, director of the agency’s Center for Devices, said: “The FDA’s new recommendations for at-home COVID-19 antigen tests underscore the importance of repeat testing after a negative test result to increase the chances of detecting an infection. could.” and Radiological Health, said in a statement.
The new guidance is based on the results of a new national study, which has not yet been published in a scientific journal. The study, led by researchers from the University of Massachusetts Chan Medical School, focused on 154 people who tested positive for the virus between October 2021 and February this year using PCR tests.
It found that among symptomatic people, two tests 48 hours apart detected 93 percent of the infection. But in the same testing pattern, only 63 percent of the infection was detected in people without symptoms.
When people without symptoms took three tests, every two days apart, the tests caught 79 percent of infections.
The results suggest that “serial testing with antigen tests is a useful method of detecting infection,” Nathaniel Hafer, a molecular biologist at UMass Chan Medical School and an author of the study, said in a statement.
The FDA said people who are concerned that they may be infected after receiving two or three negative results on at-home antigen tests may continue to test themselves, seek a more sensitive PCR test, or seek medical advice from a doctor. can consult.
People who test positive using an at-home test, the agency said, should assume they are infected and follow guidelines set by the CDC.
The CDC updated its COVID-19 guidance on Thursday, but did not change its recommendation that people who test positive for the coronavirus self-isolate at home for at least five days.
The FDA said it doesn’t require people to use the same brand of test each time.
“If you plan to use the COVID-19 antigen tests at home, have multiple tests on hand so you can test more than once,” the agency said.
(This story has not been edited by seemayo staff and is published from a rss feed)