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Why the U.S.'s supply of COVID tests has been unpredictable — and how that can change

ARI SHAPIRO, HOST:

There's been a run on at-home COVID-19 tests. Holiday travel, family gatherings and the rapid spread of the omicron variant are driving huge demand. The Biden administration says it'll set up a website next month to deliver half a billion over-the-counter tests to Americans who request them. NPR's Yuki Noguchi reports on the country's testing supply struggles.

YUKI NOGUCHI, BYLINE: Drugstore shelves are stripped of at-home COVID tests. States offering free over-the-counter tests, like Ohio and New Hampshire, ran out within hours. Susan Van Meter is executive director of AdvaMedDx, a trade group of diagnostic test makers. To consumers clamoring for rapid tests, she says more are on the way.

SUSAN VAN METER: That supply is increasing. If a rapid test isn't on the shelves in your pharmacy at this point, we would expect that it would be in the days and weeks ahead.

NOGUCHI: Van Meter says until now, it's been up to test makers to forecast demand, which has been unpredictable. What's changed, she says, is the federal government's recent investments in manufacturing and big orders. That makes planning production much easier.

VAN METER: We've been dealing with a tremendous amount of uncertainty. We've watched testing demand increase and then decline precipitously. Giving companies that sense of certainty about how many tests they should be manufacturing is incredibly helpful.

NOGUCHI: Take-home rapid antigen tests, which cost about $10 apiece and take 15 minutes to process, are suddenly very popular among U.S. consumers. But for much of the pandemic, the country's been heavily reliant on another form of COVID testing known as PCR tests. Their downsides are they're more expensive and can take up to three days to process, but they're also more sensitive and accurate than rapid antigen tests. There, too, production has ramped up. But in many places, consumers are waiting in long lines.

William Morice is president at the Mayo Clinic Labs. He also chairs the American Clinical Laboratory Association. Morice says labs still have PCR tests, but he worries because during previous surges, some testing components ran out.

WILLIAM MORICE: I think the concern is that there's not a whole lot in reserve.

NOGUCHI: Shortages of chemicals, pipette tips, collection trays - last year, those were all an issue, and Mayo Clinic had to stop running tests. Right at this moment, Morice says, the bigger problem is a lack of lab workers.

MORICE: Our biggest concern right now, like a lot of health care, is on the people side, being able to get sufficient workforce to man all the different steps that are required to do the testing.

NOGUCHI: A lot of the nation's public policies hinge on easing some of these bottlenecks, from returning to work to staying in school after exposure to COVID.

PIA MACDONALD: Any one of these massive initiatives that rely on testing is risky at this point.

NOGUCHI: Pia MacDonald is an epidemiologist and senior director at RTI International, a nonprofit research group. She says new travel requirements, for example, might be impractical.

MACDONALD: Some countries that said you need to have a test within 48 hours are changing to 24 hours. But then how many of the labs can actually process fast enough for that to be workable? It feels like a lot of people are changing strategies, and we don't know yet if actually those are going to work based on the supply.

NOGUCHI: Until widespread testing is available, experts say the key is to test smarter. In other words, using the faster over-the-counter tests before everyday gatherings like work or school and using lab-processed PCR tests for patients who might need COVID treatments, for example. Mark Stevenson is chief operating officer at Thermo Fisher, which makes PCR tests.

MARK STEVENSON: You've got to balance between speed of test and actually sensitivity of the test, and that's why it's often a balance on the choice of testing you're using.

NOGUCHI: But testing choices are just growing right now, and it's hard to plan for fast-moving variants like omicron.

STEVENSON: Demand has been very lumpy over the last two years, so we've had to manage large increases due to new variants coming in and then ramping back down. What it means as a manufacturer is either we're buying too much raw material or not enough.

NOGUCHI: Closer coordination with the federal government, he says, should make for more predictable testing supply. Yuki Noguchi, NPR News.

(SOUNDBITE OF MUSIC) Transcript provided by NPR, Copyright NPR.

Yuki Noguchi is a correspondent on the Science Desk based out of NPR's headquarters in Washington, D.C. She started covering consumer health in the midst of the pandemic, reporting on everything from vaccination and racial inequities in access to health, to cancer care, obesity and mental health.