With a soaring number of COVID cases and testing sites seeing high demand, at-home tests have often become the more convenient option.
But some doctors, including Dr. Anthony Fauci, White House chief medical advisor and the top U.S. infectious disease expert, have cautioned that not all at-home antigen tests may be able to adequately detect the omicron variant.
As the coronavirus mutates, it could render some antigen tests ineffective, said Pablo Penaloza-MacMaster, assistant professor of microbiology-immunology at Northwestern University Feinberg School of Medicine. However, most are still working.
“It depends which antigen the test is trying to detect,” he said. “If it’s going after the nucleocapsid (an internal RNA-binding protein), it’s typically better because this viral protein is more conserved, meaning it mutates less than the spike protein.”
Feeling out of the loop? We'll catch you up on the Chicago news you need to know. Sign up for the weekly Chicago Catch-Up newsletter here.
Professors said while omicron might currently evade one test, that same test may work to detect a new variant in the future.
“While the Centers for Disease Control evaluate which home tests are less effective at providing an accurate result, it is important to keep in mind that rapid tests are an important tool for keeping everyone safe as many of us travel to be with family over the holidays,” said Thom McDade, the Carlos Montezuma Professor in the department of anthropology and a biological anthropologist at the Institute for Policy Research at Northwestern University.
According to the Food and Drug Administration, both the Abbott BinaxNOW and Quidel QuickVue antigen tests are able to detect the omicron variant "with similar performance as with other variants."
However, the FDA based its findings on preliminary studies that used heat-inactivated omicron samples, not live samples. Clinical evaluations using such samples remain ongoing.
Heat inactivation can potentially alter the virus's protein structure, which may lead to changes in test performance that can be mistaken for changes due to viral mutations.
Two other tests, Linea COVID-19 Assay Kit from Applied DNA Science and Revogene SARS-CoV-2 from Meridian Bioscience should not be used, according to the agency. The FDA stated research has found both are unable to detect the variant.
While antigen tests are much quicker, they're generally less sensitive and less likely to pick up very early infections than molecular tests for any variant, according to the FDA. If people test negative with an antigen test but are suspected of having COVID-19, molecular testing may be useful for determining whether or not they have the coronavirus, the agency's website stated.
