MARY LOUISE KELLY, HOST:

COVID-19 has been around long enough that we are not even counting the waves anymore, but the virus and the tools we have to fight it keep evolving. And the guidance seems to evolve just enough with each surge that it can leave even the most diligent among us - those of us trying to follow the rules and stop the spread - can leave us feeling lost.

So with some parts of the country now seeing an uptick in cases driven by the BA.2 subvariant, we're going to check in with Dr. Celine Gounder, senior fellow and editor-at-large for public health at Kaiser Health News. She's also a former advisor to the Biden administration. Dr. Gounder, great to speak with you again.

CELINE GOUNDER: Great to be here.

KELLY: I want to start with tests, which we can all get free - these at-home rapid antigen tests. The government will just send them to you if you go to covid.gov, and you can sign up. Do these rapid tests work against the newest variants? Because they were developed for the original strain.

GOUNDER: So the rapid antigen tests you can get from covid.gov do work to pick up omicron. There's usually a day or two delay between when you might test positive on a PCR versus when you might test positive on one of these at-home rapid antigen tests. But they do work to pick up an infection, and they should be used frequently - especially if you have symptoms - to try to screen yourself.

KELLY: OK. So bottom line - you trust them. You just said, if I have symptoms - so if my nose is running or my throat is sore - if I take an at-home test and it is negative, do I need to wait a day or two and then follow up with a PCR test?

GOUNDER: Not necessarily. What I would suggest is use both of the rapid home tests that come in the box, use them a couple days apart, and if you're still worried at that point, then go out and get a PCR test.

KELLY: What about the scenario that I take a test and it is positive? Because the guidance for this is different now than it was two years ago, when we were all starting this. We now have treatments against COVID-19. How do I get them?

GOUNDER: To access treatment, you can also go to covid.gov. You can look up where in your area you can access Paxlovid, monoclonal antibodies, what facilities currently stock them, and how you can go about getting that. If you already have a primary care physician, they could also help you navigate that.

KELLY: Should everyone be getting treatment? If I test positive, but I feel fine - I have no symptoms - do I still need to do this?

GOUNDER: Right now, we have a pretty short supply of treatment, and so we're really trying to target that supply to people in whom it would really have the most benefit because we really want to make sure that we're using these treatments to keep people out of the hospital. People who are young, healthy, who don't have significant symptoms are probably not going to end up in the hospital regardless, and so that's not the best use of that short supply that we currently have.

KELLY: What is the latest guidance on isolation time? The CDC shortened the window - it's now five days. Is there consensus among experts that that is long enough?

GOUNDER: Well, what we're seeing is that people very often test positive for longer than five days. You have maybe about half of people who are negative by five days, but then the other half are positive out to even 12, 14 days. And so I think the way to address that is repeat a test if you're still positive, really try to stay at home, and if you absolutely cannot stay at home, that's a situation where you really should be masking when you're around other people so that you're not infecting others.

KELLY: Dr. Celine Gounder of Kaiser Health News, always a pleasure. Thank you.

GOUNDER: My pleasure. Transcript provided by NPR, Copyright NPR.