AILSA CHANG, HOST:
The nation's top health experts are raising alarm. New cases of the coronavirus are rising, up by more than 20% on average compared to just two weeks ago. And there are concerns that rise will accelerate even with more people getting the vaccine. Will Stone reports.
WILL STONE, BYLINE: After months of declining cases, there is a resurgence of infections in the U.S. - so far, mostly in the Midwest and the Northeast. And now hospitalizations are catching up. Pinar Karaca Mandic at the University of Minnesota is tracking this uptick.
PINAR KARACA MANDIC: We did identify 13 states with consecutive day increases in their hospitalizations, so that's concerning.
STONE: Michigan, Minnesota, New Jersey, Iowa and Delaware are some states where the trends are especially concerning. She says, in some cases, certain metro areas are driving the spike, including Detroit, Minneapolis. But overall, it's more spread out.
KARACA MANDIC: They're like small increases which then all add up.
STONE: It's a confusing picture. There's good news. More than 54 million Americans are fully vaccinated, many of them older and at high risk. And at the same time, there are fears of this fourth wave driven by a far more contagious variant, the B.1.1.7.
MIKE OSTERHOLM: I think that we really have underestimated what this B.1.1.7 virus is going to do, and it's unfortunate we're doing that.
STONE: Mike Osterholm at the Center for Infectious Disease Research and Policy. He says the spread of that variant in Europe has meant a steep increase in cases. And it's a very real warning.
OSTERHOLM: I'm feeling quite certain that in this country we're going to see exactly the same thing over the course of the next four to six weeks.
STONE: Even with about 16% of the U.S. vaccinated, the variant still appears to be spreading quickly, especially with more states opening up. But there are forces working in the country's favor. It's getting warmer. More people are outdoors, where the chance of getting infected drops. Those factors have Ali Mokdad at the University of Washington less alarmed about the surge.
ALI MOKDAD: No, this is not a big national wave.
STONE: He says that's because the vaccines are effective against this contagious variant. But in the meantime, people need to be cautious, especially those not vaccinated yet.
MOKDAD: So I'm concerned about an increase in infection among the younger population.
STONE: And he worries about people letting their guard down and new variants.
For NPR News, I'm Will Stone. Transcript provided by NPR, Copyright NPR.