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Pfizer and partner BioNTech announced Wednesday that new data show that antibodies generated by their Covid vaccine appear less effective against the Omicron variant than other variants, but that a third booster dose likely provides sufficient antibody protection.

Those data are very preliminary.


But STAT took the opportunity to catch up with Pfizer’s head of vaccine research, Kathrin Jansen, who has been one of the main architects of the development program that has helped make the Pfizer-BioNTech vaccine the most widely used of the Covid shots. Jansen emphasized that Pfizer is developing an Omicron-specific vaccine, but that she does not know exactly what strategy the world should or will take over the coming months. Instead, she is focused on being prepared for anything.

Below are excerpts from the conversation, edited for clarity and length.

Previously, you told me that this was a time for data, not panic. What do these new data tell us about whether we will need a new, Omicron-specific booster?


The one thing I think is more important than anything is that people need to get vaccinated, and when they have the opportunity to get boosters, they need to get their boosters. The world is dominated by Delta. And so we need to see what happens with Omicron, right? I mean, we now know that Omicron is in many different parts of the world. But does it take over? Will it take over Delta? It’s a very difficult question to say today what we may do, you know, in a couple of months from now.

If you ask my gut feeling, I don’t have one right now. Because I’m also concerned that to just jump to a conclusion without evidence — we may build a vaccine and then what do we know about the next variant that is coming? Right? We cannot predict what’s next after Omicron. So we may build something Omicron-specific and then the next variant of concern is coming along and then we start all over again. So that’s why I’m hesitating. You know, now we get ready. We look at the evidence. I think we are in a position to address it. But I do not have a good sense right now if we want to, need to, should have to. You have to give us a little bit more time.

One thing that I was actually elated about is that when we look at this data, after the three doses, it looks really, really good. I mean, those titers look like what we saw with wild type and other variants and what was associated with vaccine protection. So that is really, in my mind, just fantastic news. And no matter what happens, it buys us a lot of time to make sure that we have everything at our fingertips, and then can look at the complete evidence and say, “OK, now let’s decide what we’re going to do.”

As we approach these variants, is the best approach to be using one vaccine, like the Pfizer-BioNTech mRNA vaccine? Or should we be considering approaches that mix and match different vaccines? In addition to the mix-and-match study from the National Institutes of Health, J&J recently had some interesting data on the immune profiles that resulted from mixing its vaccine with the Pfizer-BioNTech one.

I think we have to be careful. Right now what we know is that two and three doses of mRNA are highly effective. And that’s a fact. We have a good safety profile. And I’m speaking for our vaccine here. So I’m not really sure, based on those data, I would do mixes and matches. Because I’m a purist, right? I always say if you have a good thing, don’t muck around with it. So in the absence of what I would call substantial data that look at a true efficacy, I would not, based on those data, make a recommendation that is different from what there is now. So you know if somebody would do a real-world effectiveness study, and it would show a difference in protection, I would say, OK, fine, there’s your evidence. But small numbers, just looking at mechanistic things, I don’t think it’s sufficient to say that’s a good idea or not a good idea. I mean, it’s just not enough data to say anything.

We’ve talked a lot over the years about vaccine hesitancy. We’ve certainly seen a lot of it over the past year. Do you have any worries about how people digest this news today and, more broadly, the discussions about Omicron?

I would think that you know that those people, they have their own agenda. They say whatever they need to say, to prove themselves, to make noise and make people insecure of what the real facts are. So I don’t know what they are going to do.

We were very careful with drafting the messages, because we don’t want to do anything that makes people insecure. Right now is not the time. We have Delta full bore in this country. And we know our vaccine is highly effective against this variant. I mean, we have shown it over and over again. So you know, with Omicron right now, yes, it’s a potential threat. But we’re generating the data and I think people need to just look at the evidence. The evidence is our vaccine is highly effective against Delta. Delta is the major variant that is circulating and we’ll see what happens with Omicron.

No matter what happens, I think we have demonstrated over and over again that our vaccine is effective in preventing Covid-19. We provide tools to make sure that people don’t end up in the hospital, in the emergency room. My advice is, for crying out loud, you know, we have the pandemic still blooming and there are a lot of people who get infected. Vaccinate, vaccinate, vaccinate. The vaccine is working. So what is there to debate?

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