SCOTT DETROW, HOST:
COVID-19 vaccines work really, really well at keeping people out of the hospital and keeping people from dying. That's what scientists say and what the data overwhelmingly shows. So many people were shocked to hear that Colin Powell, who had been vaccinated, died from COVID complications this week. But as NPR's Will Stone reports, serious breakthrough illnesses do happen.
WILL STONE, BYLINE: Colin Powell was not the typical vaccinated American. All the details about his health aren't public, but we do know he had some big risk factors. For one, he had undergone treatment in recent years for blood cancer. Dr. Jonathan Golob, who's at the University of Michigan, says these are exactly the kind of patients he expects to see with a severe breakthrough infection.
JONATHAN GOLOB: It's become quite clear that the majority of people who have received one of the COVID vaccines and then come into the hospital sick really do have something that means their immune system just was not going to respond well to the vaccine.
STONE: That could be due to cancer, a severe autoimmune disease or an organ transplant. In fact, over the summer, the CDC reported that more than 40% of hospitalizations among the vaccinated were in people with a weakened immune system. And it's why a third shot was recommended for this group. Golob says the other risk factor for Powell was his age. He was 84.
GOLOB: It seems like the vaccines work well upfront. But people who are older, the effect of the vaccine tends to wear off a little bit more quickly.
STONE: Which is why boosters are now recommended for people over 65, an age group that accounts for the overwhelming majority of hospitalizations among the vaccinated. Dr. Amit Bahl noticed this when he looked at which COVID patients were showing up at Beaumont Health, a hospital system in Michigan.
AMIT BAHL: The average unvaccinated patient was 52 years old. And the fully vaccinated patient was over 70.
STONE: Bahl's study found that if you were vaccinated, you had a 96% reduction in the chance of being in the ER or hospital.
BAHL: A bad outcome for a patient that's fully vaccinated was exceedingly rare.
STONE: That was before the surge in the delta variant. And Bahl says since then, the numbers have changed. About a quarter of the patients in their hospitals for COVID are now vaccinated.
BAHL: So you're seeing a higher percentage that are coming into the hospital. But still, proportionately, it's much less than those that are unvaccinated.
STONE: It's a key point. More people are vaccinated, so the total numbers will be bigger. But the general trend holds. Serious breakthrough infections are more likely among people who are in their 70s or older with underlying health problems. Still, it's unnerving when high-profile figures fall seriously ill and die. Angela Rasmussen is a virologist at the University of Saskatchewan.
ANGELA RASMUSSEN: I think it gives people the false impression that the vaccines aren't working. And, in fact, that is absolutely not the case.
STONE: It's hard to pinpoint just how many vaccinated people are ending up in the hospital in the U.S. because it's not being tracked in a comprehensive way. We do know the risk of getting hospitalized is 12 times higher for those who are unvaccinated. But Rasmussen says breakthrough cases are becoming more common. The country's inundated with the highly contagious delta variant. And more people are vaccinated, which leads to more breakthrough infections.
RASMUSSEN: We have more cases overall. And it really becomes a numbers game. Vaccines are wonderful. They are very effective. But they're not 100% perfect effective. And you always are going to have some cases that the vaccines don't work.
STONE: And while most breakthrough infections don't lead to serious disease, in some fraction of the population, they do, which is why the best solution for protecting the most vulnerable is to make sure everyone around them is also vaccinated.
Will Stone, NPR News.
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