ARI SHAPIRO, HOST:
The protection provided by at least one of the COVID-19 vaccines appears to have begun to fade. That's according to the Israeli Ministry of Health. But some public health officials are cautioning that it's too soon to know for sure. Joining us to explain what this means is NPR health correspondent Rob Stein. Hi, Rob.
ROB STEIN, BYLINE: Hey there, Ari.
SHAPIRO: What exactly is the Israeli Ministry of Health saying?
STEIN: The ministry hasn't released a lot of information, but a brief statement about the Pfizer vaccine says that over the past month, there's been a, quote, "marked decline" in the efficacy of the vaccine in preventing infection and symptomatic illness. The ministry says that's dropped to just 64%. It was estimated to be in the 90s. So in other words, the Israeli health ministry says the chances that fully vaccinated people could still catch the virus and develop mild or moderate symptoms has increased significantly.
SHAPIRO: That sounds really concerning. So what's the reaction been?
STEIN: You know, Ari, it's been mixed. I reached Dr. Anthony Fauci about this late this afternoon, and he said he found the Israeli statement kind of, you know, puzzling in several ways. For example, it would be very unusual for a vaccine to provide the same level of protection against both asymptomatic and symptomatic infection. And so he says he's reserving judgment until he has a chance to see more details.
ANTHONY FAUCI: It's something we would certainly want to pay attention to, but I'm not so sure we can make any major conclusions based on the information we have right now.
STEIN: Dr. Fauci says it could be that the Israelis are just testing a lot more people, so they're finding a lot more who got infected even though they were vaccinated. But he said he's trying to get more information from Israel as soon as possible to try to figure out what's really going on here.
SHAPIRO: If this is true, why would it be happening?
STEIN: You know, there are a lot of factors that could be playing a role. Israel rolled out the vaccine a lot quicker than other countries, so there's a chance that they're starting to see some of the protection begin to fade. And the health ministry notes that this happened at about the same time that the Delta variant really took off in that country. You know, that's the variant that was first spotted in India that's super contagious. And while the vaccines appear to still work very well against all the variants, including the Delta variant, lab studies suggest that it may not quite be as effective against the Delta variant. I talked about this with Dr. Paul Offit. He's a vaccine expert at the University of Pennsylvania.
PAUL OFFIT: I think you're seeing two things going on in Israel. You're seeing the effect of the Delta variant in terms of its inability of immunization to protect against mild disease caused by the Delta variant. And you're also probably seeing some fading of immunity over time.
STEIN: And that would leave some even fully vaccinated people more vulnerable.
SHAPIRO: So how worried should Americans who've gotten the vaccine be in the United States?
STEIN: Well, you know, Ari, if it's true, it definitely would be a concern. You know, this would suggest that the Pfizer vaccine and probably the very similar Moderna vaccine just doesn't provide the same level of protection as they did against the original strains of the virus. I talked about this with Saad Omer. He's a vaccine researcher at Yale.
SAAD OMER: With the original virus, you know, you would think - you know, you could think of it as a forcefield. Now, it's not that kind of a situation.
STEIN: You know, but doctors Offit, Omer and Fauci, they all stressed that the key thing is that the vaccine still remained highly effective at preventing people from getting so sick that they end up in a hospital or even die, which, you know, that's what matters most. The Israelis say that's still holding at about 93%. Here's Dr. Offit again.
OFFIT: The good news is protection against severe critical disease, the kind of disease that causes you to go to the hospital or die, is still excellent, even against the Delta variant. So the vaccine still is doing its job at keeping you out of the hospital and keeping you out of the morgue.
STEIN: But all the experts note that the Delta variant is taking over in this country, too. And, you know, it already accounts for at least one quarter of all infections and is already the dominant variant in some parts of the country. And there are still lots of people in this country who aren't vaccinated, so they're vulnerable. And, you know, the more the virus spreads, the more who will end up getting sick and dying.
SHAPIRO: That's NPR health correspondent Rob Stein. Thank you.
STEIN: You bet, Ari.
(SOUNDBITE OF TAYLOR MCFERRIN'S "DEGREES OF LIGHT")
NPR transcripts are created on a rush deadline by an NPR contractor. This text may not be in its final form and may be updated or revised in the future. Accuracy and availability may vary. The authoritative record of NPR’s programming is the audio record.