There's more potentially worrisome news for vaccinated people: In very rare cases, people experiencing breakthrough infections may be at risk for long-COVID symptoms.
That's according to a small new study of fully vaccinated health care workers in Israel, published Wednesday in The New England Journal of Medicine.
The study confirmed what's already known: That it's very rare for fully vaccinated people to get infected or sick with COVID-19. But it also found lingering COVID symptoms did develop in a handful of breakthrough cases.
Researchers studied 1,497 vaccinated health care workers at the Sheba Medical Center in Israel. Among them, only 39 got infected despite their inoculations. Of those, seven — or about 19% — developed symptoms that lasted at least six weeks, including headaches, muscle pain, loss of taste and smell and fatigue.
"It's really disturbing," says Dr. Gili Regev-Yochay, director of the infection, prevention and control unit with the Sheba Medical Center and an author of the study.
"If this is what we're going to see with all of the even mildly symptomatic infections that we're seeing now, it's definitely worrisome," she says.
Regev-Yochay and others stress that the results need to be confirmed by additional research involving many more patients who are followed for much longer. It could be a false alarm, the symptoms could be much rarer, or they could resolve far more quickly than the months of symptoms that typically plague those suffering from long COVID.
Experts stress that vaccination remains highly effective at preventing the most severe consequences of infection: hospitalization and death.
Nevertheless, other researchers agree the findings are cause for additional investigation.
"We had hoped that when you get vaccinated and even if you did have a breakthrough infection you would have enough of an immune response that would block this protracted symptom complex now known as long COVID," says Dr. Eric Topol, a professor of molecular medicine at Scripps Research.
"This study is the really first to give us an indicator that there's some long-haulers among that small group of people that had breakthrough infections," Topol says.
Regev-Yochay and her colleagues at the Sheba Medical Center noted that some of the patients in the study with lingering symptoms had severe fatigue.
"You could say these are potentially mild symptoms, but disturbing enough that some of the people didn't even return to work. It's very concerning," Regev-Yochay says.
The study was conducted when the Alpha variant was dominating Israel. Since Delta's so much more contagious and tends to produce even more virus inside people's bodies, if anything, the problem could be even worse now, Regev-Yochay and others say.
"What we're learning about this virus and frankly the heinous nature of this virus is that when it came out of China it was billed falsely as a winter respiratory virus that like influenza could cause severe and occasionally fatal pneumonia," says Dr. Paul Offit, a vaccine expert at the University of Pennsylvania who advises the Food and Drug Administration about vaccines. "But this virus is much more than that."
Other experts say the findings provide yet more evidence that fully vaccinated people need to remain cautious, and should follow the new guidelines from the Centers for Disease Control and Prevention to wear masks indoors in risky situations.
"You could imagine your vaccine providing a bit of a force field, but that's not the case anymore," says Saad Omer, a vaccine expert at Yale. "It's still pretty strong armor. But it's penetrable armor."
ARI SHAPIRO, HOST:
There's more potentially worrisome news today for vaccinated people. In very rare cases, they may be at risk for long COVID symptoms. NPR health correspondent Rob Stein joins us with the details.
ROB STEIN, BYLINE: Hey there, Ari.
SHAPIRO: So yesterday, the CDC revealed the troubling news that fully vaccinated people might still be able to spread the virus. What's new today?
STEIN: It's a new study from Israel, and it's really the first to suggest that vaccinated people may - and I really need to stress the word may - be at increased risk for long COVID symptoms. Researchers at the Sheba Medical Center in Israel have been following hundreds of doctors and nurses and other health care workers who got vaccinated. And the good news is the researchers confirmed that those so-called breakthrough infections are extremely rare. And when they do happen, most people get either no symptoms or just mild symptoms.
But now comes the disturbing part. In this study, about one in five people who got infected even though they were vaccinated - 19% - experienced symptoms found in long COVID patients that lasted at least six weeks.
Here's Gili Regev-Yochay. She led the study.
GILI REGEV-YOCHAY: They had severe fatigue. They continued to have loss of taste and smell. Some of them did not return to work because they were so tired, you know, muscle pain, headaches that were continued. You know, you can say these are potentially mild symptoms, but disturbing enough that some of the people didn't even return to work. It's very concerning.
STEIN: Now, it's really important to stress that these are very small numbers. Out of about 1,500 vaccinated health care workers in the study, only 39 got infected, and only seven had these symptoms that lasted more than six weeks.
SHAPIRO: So with all those caveats and the small sample size, how worried should vaccinated people be?
STEIN: Yeah. So for now, it's definitely not time to sound any major alarm bells. Clearly, you know, more research is needed to see if this holds up when more people are studied over a longer period of time. It could turn out that this is just a false alarm, or it's even rarer than this, or that these symptoms, you know, do end up going away relatively quickly and don't plague people for months, like long COVID. Nevertheless, it is worrying. I talked about this with Dr. Eric Topol at the Scripps Research in California.
ERIC TOPOL: We had hoped that when you get vaccinated, and even if you did have a breakthrough infection, that you had enough of an immune response that would block this protracted symptom complex now known as long COVID. This study is really the first to give us an indicator that there's some long-haulers among that small group of people who had breakthrough infections.
STEIN: Now, it's also important to note that this study was done when the alpha variant was dominating Israel. And since delta's so much more contagious and tends to produce even more virus inside people's bodies, if anything, the problem could be even worse now.
SHAPIRO: That does sound like an important detail. So what should vaccinated people do about this?
STEIN: You know, the first thing everyone stresses that I talked to about this is that the vaccines are still really powerful at doing the most important thing, which is, you know, keeping people from getting really sick or dying. So the most important thing anyone can still do now is get vaccinated. But it is a reminder that vaccines, you know - they're not perfect. And this virus keeps turning out to be nastier than we've thought. Here's Saad Omer. He's a vaccine expert at Yale.
SAAD OMER: You can imagine your vaccine providing a bit of a force field, but that's not the case anymore. It's still pretty strong armor, but it's penetrable armor.
STEIN: And it could turn out that some vaccinated people do end up with health problems that linger. So this is just one more reason why it's more important than ever that vaccinated people not let down their guard and, you know, follow those new recommendations from the CDC that they put back on their masks when they're in risky situations.
SHAPIRO: That is NPR's Rob Stein.
Thanks a lot, Rob.
STEIN: You bet, Ari. Transcript provided by NPR, Copyright NPR.