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There is a huge blood shortage in the U.S. The Red Cross is calling it a crisis - the worst in over a decade. It's just one more sign of the health care disruptions that patients are facing during this pandemic. NPR's Will Stone reports.

WILL STONE, BYLINE: Isaac Bishop could tell America's blood supply was stretched. Bishop is 18. Last year, he was diagnosed with an aggressive form of bone cancer and started chemo two weeks later. Over time, he needed blood transfusions, but some days he could only get half of what he needed. Then, in December, he showed up at the hospital, they checked his blood counts...

ISAAC BISHOP: They were low enough to the point where I could get blood, and they didn't have any that they could give me. So they said, come back tomorrow or the next day, and maybe we'll have something to give you.

ROB BISHOP: Those are very hard things to hear as a parent.

STONE: That's Rob Bishop, Isaac's father.

R BISHOP: A blood transfusion is going to change the way he feels in a matter of 15 minutes and help him to be stronger.

STONE: That's because when his blood counts were low, Isaac would feel weak and lightheaded.

I BISHOP: I feel like I'm going to pass out, and I'll need to sit down and lay down when I'm doing things. So I'll stay in bed most of the time.

STONE: Ultimately, Isaac was able to get the transfusion a few days later, but more than once they were told there wasn't enough blood as the shortage became more serious. And then last month, the Red Cross declared it a crisis. It wasn't just felt by cancer patients. In large metro areas, some hospitals are postponing up to 25% of elective surgeries, according to the health care company Vizient. Dr. Randall Oyer directs the cancer institute run by Penn Medicine in Lancaster, Pa.

RANDALL OYER: I've been a physician for a little more than 40 years, and no, I have never seen a situation like this before.

STONE: Oyer says Penn Medicine even assembled an emergency response team made up of surgeons, oncologists and others to draw up plans in case they had to ration blood. They started offering employees a full day of paid time off if they donated.

OYER: As soon as that incentive was offered, you know, hundreds of blood donation slots filled up immediately.

STONE: The reality is that blood products have a shelf life. Red blood cells can last up to a month, platelets less than a week.

VICKI FINSON: We are still day to day.

STONE: Vicki Finson is with Bloodworks Northwest in Seattle.

FINSON: We have to micromanage every order, and we have to work with our hospitals to try to triage where that blood should be.

STONE: There's no single reason for the severe shortage. Dr. Jennifer Andrews is medical director of the blood bank at Vanderbilt University Medical Center. She says January is typically tough because of the holiday season, and blood donations have been down since the start of the pandemic. But the last few months brought about a sort of perfect storm.

JENNIFER ANDREWS: What the crisis showed is how precarious the blood supply is and how vulnerable it is.

STONE: Big winter storms, the omicron surge and staffing shortages added to the problem. Andrews says it's also hard to know how much blood is actually out there.

ANDREWS: So in the midst of these shortages, my staff in the blood bank - we're calling all the other hospitals in our city, and we're asking, do you have any extra for us?

STONE: The shortage has eased up slightly over the past month, but it remains dire in many parts of the country. And now, as hospitals catch up on the backlog of delayed surgeries, demand is staying high. Kim Kinsell of Lifesouth Community Blood Centers says the problem isn't just logistics. She says historically, baby boomers have helped prop up the blood supply, but as they age, they're giving less and needing more.

KIM KINSELL: We've seen this trend over the last two years has really been magnified with COVID, that we really need a younger donor base to step up.

STONE: The question is, will they, as the omicron wave recedes and giving blood becomes easier again? Will Stone, NPR News. Transcript provided by NPR, Copyright NPR.