Countering earlier concerns, a real-world study finds that a widely used at-home coronavirus test called BinaxNOW is as effective at detecting omicron as other COVID-19 variants.

The study of Abbot's rapid antigen test included more than 700 people who visited a walk-up testing site in San Francisco.

The test detected 65% of infections caught by more sensitive PCR tests, but pinpointed 95% of people with the highest levels of the virus. Among those with high levels of the virus, the test identified 98% of those with symptoms and 90% of those without symptoms.

The results are about the same as what was found in real-world studies before omicron emerged, according to the researchers.

The test is "working as it was designed," study author Joseph DeRisi, a biochemist at the University of California, San Francisco, told The New York Times. "There does not seem to be any performance deficit with Omicron."

The study, published on the preprint server medRxiv, has not yet been peer-reviewed.

Some earlier preliminary studies had raised questions about whether rapid antigen tests might be less sensitive to omicron than other variants.

Scientists are still trying to determine how well at-home tests work for omicron, Dr. Janet Woodcock, acting commissioner of the U.S. Food and Drug Administration, said Tuesday during a Senate hearing on the federal coronavirus response, the Times reported.

"We believe all of them detect omicron," she said. "We simply feel they are somewhat less sensitive than they were to some of the previous variants."

But the new research, done with nasal swabs, does not address how early in an infection the rapid tests can spot the variant, or whether they would perform better with saliva samples. Also, the BinaxNOW results cannot be extrapolated to other rapid tests, which must be evaluated individually, the researchers noted.