The Food and Drug Administration said Tuesday that preliminary studies show that some fast-acting antigen tests may be less resistant to detecting variants of the highly infectious omicron coronavirus.
The FDA, along with researchers from the National Institutes of Health, used samples of patients who were certified by the omicron variant to study the effectiveness of antigen tests. The center said the preliminary results suggest that antigen testing "detects omicron variability but may reduce sensitivity," meaning that tests may miss out on infection, known as "false negative."
The number of cases is increasing across the country, making there a great need for immediate home screening. Antigen testing can be done at home, with results in a few minutes, while PCR tests are performed in labs and there are long periods of change.
The FDA did not say that individuals should avoid using antigen tests.
"The FDA continues to authorize the use of these tests as directed to authorized labels and individuals should continue to use them in accordance with the instructions included in the tests," the agency said in a statement. "Antigen tests are usually less sensitive and less likely to detect infections earlier than cell tests."
The FDA did not specify the types of tests used in the study.
Gigi Gronvall, senior researcher at the Johns Hopkins Center for Health Security, said in a telephone interview that the FDA findings underscore the challenge posed by the virus.
“With any new model, we have to make sure the tests work, and it looks like the tests work in this case. But they do not get diseases early in previous versions, ”he said. “So if you feel any symptoms but are not diagnosed, it is not a prison release card. You may have to reevaluate and hold back and think you don't have it. ”
The CDC shortens the recommended separation time for COVID
DEC. 28, 202102: 25
The FDA recommended a follow-up test on Tuesday to anyone who tested positive for a quick antigen test but had symptoms.
"Once a person is tested for antigen, they should isolate themselves and seek follow-up help from a health care provider to determine the next steps," the organization said.
President Joe Biden announced this month that management will distribute 500 million instant tests to US homes free of charge from January. The federal government is also planning to establish new testing centers across the country, with more than 20,000 already in operation.
The Centers for Disease Control and Prevention issued a new directive on Monday stating that people who are tested for Covid-19 but have no symptoms should be separated for five days, down from the previous 10-day recommendation. He says the change was due to growing evidence that the virus is highly contagious within two or three days after symptoms appear.