In a tiny new real-world investigation, researchers found that two frequently used at-home antigen tests, the Abbott BinaxNOW and the Quidel QuickVue, may be ineffective at detecting certain Omicron infections, even when patients had significant quantities of the coronavirus in their bloodstream.
It took an average of three days for persons to test positive on a quick antigen test after receiving a positive P.C.R. result for the first time. According to the findings of the research, which was carried out by many members of the Covid-19 Sports and Society Working Group, in four instances, persons transferred the virus to others while the fast test revealed a negative result in the other two cases.
If the infections were missed, it is unclear whether this was due to the fact that antigen testing are intrinsically less sensitive to Omicron or if this was due to the fact that saliva tests may be more effective at detecting the new variety.
However, the findings are consistent with previous preliminary indications suggesting the at-home tests that many Americans have come to depend on — at least as they are now done, with a nose swab — may be ineffective in detecting certain Omicron cases in the early stages of the disease.
The researchers claimed they communicated their findings with government authorities, including those at the White House, the Food and Drug Administration, and the Centers for Disease Control and Prevention, in real time, while the outbreaks were taking place last month, according to their statement.
Many of the research are preliminary and modest in scope, and much more information is required. The tests, which can be performed at home and provide findings in minutes, continue to be an essential public health tool, and positive results are particularly likely to be useful, according to many experts. (The wait for the findings of a P.C.R. may be many days.)
Omicron has been identified by a number of firms as being detectable, and numerous independent scientists have said that they think the tests should be able to identify the variation, particularly when it is present in large concentrations. However, a few recent research raise concerns regarding the sensitivity of the tests.
According to Bruce Tromberg, head of the National Institute of Biomedical Imaging and Bioengineering, the Food and Drug Administration’s update was prompted by a review the agency is doing with the National Institutes of Health. The antigen tests were examined by the scientists using pooled samples of nasal mucus acquired from many persons who had Omicron, as well as pooled samples of nasal mucus collected from comparable people who had Delta.
Because of Omicron’s quick reproduction, there is a shorter window of opportunity to capture the virus before it spreads. As a result, individuals may need to test themselves as soon as feasible after a suspected exposure and as near as possible to an anticipated gathering or event, according to specialists. They may also be required to test themselves on a more regular basis in general, which may be difficult when the tests are in limited supply.