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Do vaccines stop infections from the omicron variant? Early results are released

DEBBIE ELLIOTT, HOST:

COVID-19 hospitalizations are rising in the U.S. And with the omicron variant reported in at least 57 countries and 19 U.S. states, scientists are trying to answer the main question we all have - will vaccines work against this new variant? Last night, scientists in South Africa released preliminary results from a study that begins to answer that question, and NPR's Michaeleen Doucleff is here to explain. Tell us more about this study and what it finds.

MICHAELEEN DOUCLEFF, BYLINE: Yeah. So just to be clear, it's a very small study and hasn't been peer-reviewed yet. But their data suggests that vaccines will be much less effective at stopping infections from omicron, but they will still likely offer protection against severe disease.

Here's what they did. They took blood from people who had been vaccinated with two shots of the Pfizer vaccine and looked to see how well their antibodies killed or neutralized the virus. Everyone in the experiment was able to fight off earlier versions of the virus quite well. But against omicron, that ability dropped dramatically. On average, the antibodies, which fight off the virus, were 40 times less potent against omicron.

ELLIOTT: Forty times - so 40 times less effective. That sounds like a big number.

DOUCLEFF: Yeah. This drop in potency is much greater than scientists have seen with other variants. I spoke to Pei-Yong Shi. He's a virologist at the University of Texas Medical Branch at Galveston. He's doing similar experiments for Pfizer. He's never seen a drop like this.

PEI-YONG SHI: It's astonishing, the - in terms of the reduction. That's my first response.

DOUCLEFF: But he says, you know, this finding isn't surprising because omicron has many mutations already known to weaken the power of antibodies.

ELLIOTT: So does this mean that we're going to see more and more breakthrough infections as omicron spreads?

DOUCLEFF: Yes. All scientists I talked to say this is very likely because in South Africa, they're seeing a lot of reinfections. So that observation combined with this lab data indicate that omicron is good at bypassing antibodies that the immune system makes.

Now remember, though, the vaccine isn't just about protecting against infections. It's also about protecting against severe disease and death. And there's reason to believe that the vaccines will still do that. Most of the people in the South African experiment did retain some ability to kill the virus. And scientists say that even just a little bit of antibody activity can be enough to prevent you from ending up in the hospital.

And also remember that the immune system has other tools besides antibodies, and these can also ward off severe disease. In particular, the T cells can clear out the infection - can clear out the virus after an infection. And scientists think those may hold up better against omicron.

ELLIOTT: OK. This South Africa experiment only looked at two shots. What about the booster? Is that going to help against omicron?

DOUCLEFF: So just this morning, there's data out from Germany in a press release from Pfizer showing that the booster will significantly raise the potency of your antibodies, at least in the short term. So, again, the message is clear - get vaccinated. And if you've had two shots, get a booster. It's your best protection against severe disease.

ELLIOTT: NPR's Michaeleen Doucleff, thank you.

DOUCLEFF: Thank you.

(SOUNDBITE OF NYMANO'S "BLURRY FEAT. HYUME") Transcript provided by NPR, Copyright NPR.