ADRIAN FLORIDO, HOST:

Does it feel like everyone you know has COVID right now? For a lot of people, the answer is yes. And that's because in many parts of the country, COVID-19 case numbers are going up and up. Much of that increase is being driven by variants of omicron.

Well, Andy Slavitt thinks that this new wave of growth is giving us a glimpse into what endemic COVID will look like once we get there. Slavitt was a senior adviser to President Biden on COVID and was the head of Medicare and Medicaid in the Obama administration. Andy Slavitt, welcome back to ALL THINGS CONSIDERED.

ANDY SLAVITT: It's great to be here, Adrian.

FLORIDO: You said in a thread on Twitter that we're getting clues about what COVID will look like when it's an endemic disease. But before I ask why you think that, remind us what the endemic phase of a disease is and how that is different from the pandemic phase.

SLAVITT: Well, yeah, let's be clear - we don't know if we're in an endemic phase yet, and we probably won't know till afterwards because I think the best definition of endemic that I've heard is just when the surprises are gone, and it becomes predictable. Endemic doesn't necessarily mean everybody's safe. Endemic doesn't necessarily mean people are no longer losing their lives. It just means it's following a predictable pattern. And what we don't know but we may be witnessing are some clues as to what a predictable pattern will look like when we settle into one.

FLORIDO: Why is it so important for us to know that we're in an endemic phase, assuming we get there at some point?

SLAVITT: I think the real question is, what are the tools that we need to have as a country in order to live as normal life as possible? The best news of all is that we have incredible scientific tools - vaccines, boosters, oral therapeutics. And while none of them are perfect on their own, when you combine them with what our own immune system does and the continued kind of improvement of these tools, the layered immunity we have, COVID should become less and less fatal. It will still be dangerous and still dangerous for people who are frail, people who are immunocompromised, but even in those situations, the tools are better and better.

So what we really want to know is, is it going to get any more severe? And is it going to get any more frequent? And are the vaccines and tools we have going to continue to work? And if we are in a situation where we need to update our vaccines once or twice a year, we need to be prepared to do that.

FLORIDO: What are the unknowns out there that could change your assessment about how close we're getting to an endemic phase of this disease?

SLAVITT: So scientists talk about this notion of drift versus shift. And what they mean by that is a drift virus would indicate that we will just continue to see more progressions, almost laddering up of new omicron - we have 1.1, 1.2, 1.3, 1.4. And a drift is a better scenario than a shift. A shift is where we would get an entirely new Greek letter, in this case with completely different mutations and characteristics. And what's better about a drift is that our body is, generally speaking, forming better immunity in prior versions that protect us against newer versions. And our vaccines will, generally speaking, be more aligned to what we see next than they would be if we were to see a shift.

So the big question is, are we going to be in drift mode and for how long will we be in drive mode, or are we going to go back to shift mode where we'll see a delta, an omicron, etc.? No one knows the answer. But there are a number of scientists who say that the number of times we'll see a major shift could be pretty rare, could be as infrequently as once a decade.

FLORIDO: As you said, the predictability that comes from the endemic phase will help us figure out what kind of public health measures to use. But I wonder if it'll also discourage people from taking precautions, like masks and vaccinations.

SLAVITT: Well, predictability will be a good thing. You know, if we knew that we were going to see COVID-19 every June and every December, we might not like that, but at least it would tell us that we can take the kinds of precautions that we need to take then, and we don't need to take them other parts of the year. What bothers people is feeling like they're taking precautions in periods of time when it doesn't matter. So, you know, we don't give people flu shots in April, May and June because the risk of the flu is quite low then.

So if we understand this well enough, and it becomes predictable enough, I think you can then create targeted campaigns to say, hey, every time that this happens, these are the precautions we ought to take. We ought to wear masks. We ought to stay away from these types of crowds and these types of situations if we're immunocompromised. But other times of the year, go on, live your life. Things will be, more or less, safer.

FLORIDO: I've been speaking with Andy Slavitt. He's a former Biden and Obama administration official, the author of "Preventable" and the host of the "In The Bubble" podcast. Thanks for speaking with us.

SLAVITT: Thank you, Adrian. Transcript provided by NPR, Copyright NPR.