Several common rapid antigen tests work well for Omicron, according to a new study.
Several rapid antigen tests widely used in the United States—Abbott BinaxNow, BD Veritor At-Home, and Quidel QuickVue—are effective in detecting the Omicron variant of the coronavirus. According to a new real study, this eases concerns about possibly false-negative test results. Tests were conducted similarly for Omicron and the Delta variant in a study that was published on Monday but has yet to be published in a peer-reviewed journal. According to a study conducted in collaboration between the National Institutes of Health, the Food and Drug Administration, and the UMass Chan School of Medicine. The difference between the variants was not statistically significant.
The researchers found that the tests performed best among those with the highest viral load, detecting more than 90 percent of Omicron and Delta infections in that group.
“This study adds to the body of evidence that Omicron can be detected with the home tests we have,” said Nathaniel Hafer, a molecular biologist at the University of Massachusetts School of Medicine and study author.
Rapid antigen tests, which are less sensitive than PCR tests, are designed to detect proteins on the surface of the virus. If genetic mutations change these proteins, it could affect the ability of the tests to detect the virus. Therefore, every time a new variant appears, researchers need to reevaluate the tests.
Early laboratory studies have shown that some antigen tests may be less sensitive to Omicron detection than previous options, meaning they may produce more false negatives. FDA warned of this possibility at the end of December.
But experts noted that the tests still need to be evaluated in large, real-world studies.
New findings from ongoing research in the US which began in October and was designed to evaluate the performance of rapid antigen tests in asymptomatic people.
Participants received in the mail home PCR kits and one of three randomly selected brands of rapid antigen tests. They collected PCR samples and performed rapid antigen tests every 48 hours for 15 days. They sent their PCR samples to a lab for testing and reported the results of their rapid antigen tests on a research app. (They were also asked to upload photos of their rapid test results.)
About 6,000 people took part in the study between October and the end of January. The new analysis focuses on 153 people who tested positive for the virus at least once as a result of a PCR test at some point during this period. The researchers concluded that approximately sixty percent had confirmed or probable Omicron infections using a combination of sequencing data and information about when each person first tested positive. The rest presumably had a Delta.
The PCR results showed that about half of the 153 participants had a high viral load. Among this group, 96 percent of those with Omicron infections and 91 percent of those with Delta infections tested positive for the antigen within two days of a positive PCR result.
“The study showed that at higher numbers of virus, these antigen tests do a good job of identifying cases,” said Matthew Binniker, director of clinical virology at the Mayo Clinic, who was not involved in the study. “The real problem with false negatives comes from lower levels of the virus.”
Experts are urging people who have symptoms of the virus or who have been exposed to the virus to have multiple antigen tests over several days to increase the chances of finding an infection.