NOEL KING, HOST:
Remember the excitement when people got the first coronavirus vaccines last month? Well, public health experts at the time pointed out that both vaccines available in the U.S., of course, require two shots. Those second shots started going into arms this week. Here's Will Stone.
(SOUNDBITE OF ARCHIVED RECORDING)
UNIDENTIFIED PERSON #1: So this...
UNIDENTIFIED PERSON #2: Your COVID dose.
UNIDENTIFIED PERSON #1: ...Is your second dose.
UNIDENTIFIED PERSON #3: OK.
WILL STONE, BYLINE: No one needed to convince Dr. Megan Ellingsen to show up for her second shot of the coronavirus vaccine. Ellingsen got her first shot the same day she had to do a procedure on a hospice patient at his home.
MEGAN ELLINGSEN: A week later, we found out he had COVID. And I was in this small bathroom with him for 45 minutes. And you can imagine how frightening that was.
STONE: Yesterday, Ellingsen became one of the first to be fully vaccinated at PeaceHealth St. Joseph Medical Center in Bellingham, Wash.
ELLINGSEN: I'm so immensely grateful to everybody who's brought this from the research table to us.
STONE: This second shot boosts the efficacy of the vaccine to about 95%.
Kate Morin (ph), a COVID ICU nurse, calls her slightly sore arm a huge relief.
KATE MORIN: I'm just much more afraid of COVID than I am the vaccine. I've seen people die. I've seen people very, very sick.
STONE: Orchestrating this two-shot vaccine is not as simple as it might seem. It has all the complications of the first shot, like a limited shelf life once it's thawed out. And people getting it need to show up at the right time, which requires careful recordkeeping and coordination.
CHARLES PROSPER: We have seen good coordination, good vaccine supply.
STONE: That's PeaceHealth hospital executive Charles Prosper. He says there was a brief delay this week in the shipment of second doses, but they've got extras, a buffer just in case.
PROSPER: That has actually kept us in good shape, with no risk of individuals missing their second dose.
STONE: But supplies are less certain in some places. Florida is telling hospitals not to hang on to any. And they're counting on manufacturers delivering the second doses on time.
MARY MAYHEW: Certainly, it creates some angst.
STONE: Mary Mayhew is president of the Florida Hospital Association.
MAYHEW: The bottom line is demand is absolutely far exceeding supply.
STONE: Second doses of the earliest vaccine from Pfizer are being given in Florida. But the second shots of Moderna vaccine, which are due to go into arms in about two weeks, have not yet arrived.
MAYHEW: Everybody wants to have the staff scheduled, to have the appointments. And it is just simply challenging to manage all of that without having the certainty of when that will arrive.
STONE: Because the U.S. vaccine rollout is going slower than promised, some scientists believe the second shot should be skipped for now. They argue that would get more people at least some protection quickly. But the FDA says that strategy is not rooted solidly in the available evidence.
Dr. Glenn Morris directs the Emerging Pathogens Institute at the University of Florida.
GLENN MORRIS: The real problem is getting enough doses into enough people.
STONE: And Morris says in some parts of the country, including Florida, where websites have crashed and crowds have gathered outside the clinics, that could warrant delaying the second shot.
MORRIS: In other circumstances, it may not be necessary. And the better part of valor is to go ahead and proceed with the standard dosing regimen.
STONE: Dr. Mark Fendrick at the University of Michigan studies other vaccines that require multiple doses. He says just getting people to follow through with a second shot is hard, even when supply isn't an issue.
MARK FENDRICK: We can't let the last leg of this remarkable COVID-vaccine journey, this so-called second-dose problem, stop us from completing the quest to get our lives back.
STONE: And people need to get those second doses at the same time the U.S. is trying to rapidly expand the number of people getting their first. For NPR News, I'm Will Stone. Transcript provided by NPR, Copyright NPR.