NPR's Mary Louise Kelly talks with Dr. Wilbur Lam, a lead investigator assessing COVID-19 diagnostic tests for the U.S. government, about detecting the omicron BA.2 subvariant with rapid tests.

Transcript

MARY LOUISE KELLY, HOST:

The end of public health restrictions around the United States may feel like the endgame of the pandemic. Try telling that to COVID. For weeks, infection counts have been slowly ticking up in the U.S. with the omicron BA.2 subvariant the dominant strain of the coronavirus in the country. Those rapid at-home tests that so many of us now have stashed in a drawer - they could help if we can trust them with this subvariant.

So let's bring in Dr. Wilbur Lam, professor of pediatrics and biomedical engineering and one of the lead investigators assessing COVID-19 diagnostic tests for the federal government. Dr. Lam, welcome.

WILBUR LAM: Thanks for having me.

KELLY: Let's start there. Can we trust the rapid tests? Can we tell that the rapid tests pick up omicron BA.2 as well as they did previous variants?

LAM: Yeah. In general, I think the answer is yes with a couple of caveats. One caveat is that these rapid tests don't detect as much virus as the standard PCR test. However, to mitigate that, because these things are more available than PCR testing, each person, if they're able to get hold of them, can test themselves serially, like when they - the first day of symptoms. They can test themselves on the second day, third day. And that serial testing does end up mitigating the drawbacks of at least the accuracy of these types of tests compared to PCR tests.

KELLY: So the key is repeat, repeat, repeat.

LAM: Exactly, if you're able to get them.

KELLY: I mean, you may be hearing some of the same things I have. Purely anecdotal, but a lot of friends who are symptomatic, they take the rapid test, it's negative. They take it again, it's negative. When they finally get a PCR test, positive. And what do you say to them?

LAM: Yeah, and that's the other caveat with omicron. One aspect about omicron is biologically, it likely is more infective than the other previous variants. They jump from person to person much more quickly than the other variants. So the test might not even have time to pick it up before it jumps from one person to another person in a household. So the test theoretically still works. It's just that the biology of this virus may enable it to jump from one person to person before the test can even catch it.

KELLY: In terms of what we should do, if I have COVID symptoms, I take my rapid test. It's negative. What is your advice? I mean, I hear you saying take it again the next day and the next as long as you have symptoms. Should I also go get a PCR test? Should I think about isolating?

LAM: Yeah, that's a great question and something I deal with my own family and even my patients. So I would say it's really about the context. If you're going to - example - for - to a large meeting or conference, and you're trying to screen yourself, and if you get COVID, as you've said yourself, this newer variant isn't as fatal. Maybe that's OK. However, if you're trying to test yourself, and you're going to visit, for example, an elderly family member who is immunocompromised due to cancer and chemotherapy, that's when I would say take some extra precautions even if you're negative. So continue to mask, test again, maybe get a PCR test.

KELLY: Okey-doke. Just about 30 seconds left, but how is supply doing? I mean, I remember in the winter, it was hard to get a rapid test. Are there more out there? Are there enough?

LAM: Thankfully, at least as of right now, supply's OK, and that's thanks to some of the new government policies that's been instigated since the winter where we've been trying to bring in more tests, absolutely.

KELLY: OK. Dr. Wilbur Lam - he's a professor at Emory University and Georgia Tech and a physician with Children's Healthcare of Atlanta. Dr. Lam, thanks so much.

LAM: Thanks for having me. Transcript provided by NPR, Copyright NPR.