Can COVID Tests Detect New Variants?
By James Vito, DMD
In
Dr. Vito's Newsletters
December 13, 2022
New COVID variants like BQ.1.1 and XBB are circulating, causing concern that at-home rapid tests may not be effective at detecting them. But experts say that currently, our existing antigen tests can spot an infection—so long as you test properly and repeatedly.
Nathaniel Hafer, PhD, an assistant professor of molecular medicine at UMass Chan Medical School, said the variants we are now seeing may behave differently, but the part of the virus that antigen tests detect hasn’t changed.
“The important thing to recognize there is that many of the mutations are in the spike protein. That's obviously important for immune evasion and how our body can recognize and fight off the virus.”
A new study published in the science journal, Cell found that rapid antigen tests efficiently detect all current and previous SARS-CoV-2 variants. “Based on our findings, none of the major past and present SARS-CoV-2 variants of concern contain mutations that would affect the capability of current rapid antigen tests to detect antibodies,” study author Filipp Frank, PhD, an assistant professor in the department of biochemistry at Emory University, said in a statement
While the spike protein of the SARS-CoV-2 virus has indeed mutated since the start of the pandemic, the N protein in new variants is still detectable on antigen tests.
With rapid antigen tests, people either swab their nostrils or the back of their throat to collect a sample. That sample is then mixed in a tube with a liquid, then the mixed liquid is squeezed onto a test strip.
Antigen test strips have antibodies on them, which are just like the antibodies we have in our bodies that recognize foreign compounds. If you are positive for SARS-CoV-2, the swab sample will react with the antibodies on the test and show a positive result.
At-home antigen tests are accurate about 80% of the time in people who are infected with SARS-CoV-2. PCR tests have an accuracy rate of about 95%.3
Take home message: Rapid, at-home antigen tests can still detect new variants—including BQ. 1.1. and XBB. While we might need to tweak our antigen tests in the future, we are OK with existing ones for now. Experts say testing repeatedly for a few days will give you the most accurate results.
Until Next time: Stay Safe, Stay Healthy and Stay Careful out there
James A Vito, D.M.D.