SAN FRANCISCO, Calif. (KRON) — While the FDA says at-home coronavirus tests may be less sensitive to the omicron variant, some doctors and researchers say that statement leaves out some crucial information.
They say the at-home antigen tests are still an important tool and produce mostly accurate results.
As at-home COVID-19 antigen tests fly off the shelves at your local stores, some people are now questioning their accuracy in detecting the omicron variant.
Some doubts have been raised after the FDA put out a report on Tuesday, writing: “Early data suggest that antigen tests do detect the omicron variant but may have reduced sensitivity.”
“FDA didn’t do any favors to anybody today by reporting out sensitivity. What they should’ve been reporting out is negative predictive value, which is a different cut when you array this in a two-by-two table,” said professor of epidemiology at UCSF Dr. George Rutherford. “When you have a negative test how sure can you be that it’s negative, truly negative? And the answer is when there’s 45 cases per 100,000 in San Francisco, for example, the vast majority, 99% are going to be true negatives.”
Rutherford disagrees with how the FDA put out the information, saying the antigen tests are performing well with detecting true negative cases.
“FDA’s giving you a different statistic, which, you know, you’d like to think would perform better, but given the relatively low rate of disease, it’s performing quite well,” Rutherford said.
However, Rutherford reiterates what we already know about the at-home tests: that timing is crucial and the PCR molecular tests are the most accurate option.
“There are some timing issues with it. If you do it too early, it’s not going to pick it up. That’s not a fault of the test, it’s just the timing of it,” Rutherford said.
If using the at-home rapid tests, Rutherford says you can count on accurate results as long as you test twice, a couple of days apart.