As the omicron subvariant XBB.1.16 takes off in the U.S., questions have emerged around whether current at-home COVID-19 tests accurately detect the strain.
CDC estimates indicate the strain accounts for 7.2 percent of U.S. cases, and experts anticipate it will become dominant in the coming weeks. Anecdotally, the strain appears to be causing conjunctivitis among children in India, where it is causing a surge. The potential shift in symptom set raises the question about whether the tests can accurately detect the evolved virus.
As the prevalence of XBB.1.16 grows, experts don't anticipate the accuracy of at-home tests to be affected, since most are designed to recognize the virus' nucleocapsid protein, not the spike protein. Health officials have said XBB.1.16 has a very similar profile to XBB.1.15 — the dominant strain in the U.S. — with one additional mutation in the spike protein that has shown increased infectivity and a potential increase in pathogenicity in lab studies.
"The majority of SARS-CoV-2 variant mutations occur in that spike protein and so thus far, the ability of at-home [tests] to detect the virus has not been affected, through many interactions of changing variants, because the nucleocapsid protein has not changed much as the virus has evolved," Amy Karger, MD, PhD, clinical pathologist and associate professor at the University of Minnesota Medical School in Minneapolis, told Becker's.
At-home COVID-19 antigen tests are expected to be around 80 percent accurate at detecting a COVID-19 infection, according to the FDA. They are less sensitive than polymerase chain reaction tests — the gold standard — and should thus be repeated after a negative result regardless of symptoms.