Published on Jul 02, 2021

Video Transcript

[MUSIC PLAYING] DR.JOHN WHITE: Welcome, everyone. I'm Dr. John White, chief medical officer, WebMD and you're watching Coronavirus in Context. Have you been hearing about the boosters? Are we going to need a booster in the fall? I'm not so sure. And to help provide some insights, I've gone to one of the experts, Dr. Rachel Presti. She's an associate professor of infectious disease at Washington University, st. Louis and an author of a study that looked about the durability of the mRNA vaccine. Dr. Presti, thanks for joining me.

DR.RACHEL PRETSI: It's nice to be here. Thank you.

DR.JOHN WHITE: Well, let's get right to it because everybody wants to know how long this immunity last? Are we going to need a booster? Does it protect against the variance? Your study recently came out in the journal, Nature. I want you to describe it to our viewers and what you found.

DR.RACHEL PRETSI: So what we looked at was people who had gotten the Pfizer vaccine. So I want to be very, very clear that the only vaccine we looked at was the Pfizer vaccine. So we looked at people who were eligible to get that vaccine very early. So we started enrolling people in December or January and we looked at two different things.

So initially, we looked at blood and looked at the B cell produced, the antibody cells producing cells, the B cells in the blood over time. And then in some of the participants, we also looked at what is happening in the lymph nodes. And what we found was in the blood you see good antibody responses that's already sort of been seen in all of these vaccines. And the interesting thing that is potentially relevant is that it looked like even in people who'd previously been infected with COVID, there was a boost, there was an increase in their response in the blood after getting the vaccine.

So there's been some discussion about whether or not if you had COVID if you still need a vaccine. I think this would suggest that having a vaccine there's a benefit.

DR.JOHN WHITE: What period of time did you look at?

DR.RACHEL PRETSI: So starting in December and then we have data through about March, April. So 12 weeks or so. About three months after people had been fully vaccinated. So after they've gotten their two doses, we started looking in the blood.

DR.JOHN WHITE: And what did you conclude? This is the exciting.

DR.RACHEL PRETSI: So that is what we saw. We saw that people had nice antibody responses but that they also even more importantly had B cells in their blood. So antibody producing cells in their blood and we saw that there were sort of lasting through that time period.

DR.JOHN WHITE: That's not something we see with all vaccines, correct?

DR.RACHEL PRETSI: So, you know? In the blood we do-- what we would expect to see with any vaccine is that you get antibodies that are produced in the blood and then you expect those antibodies in the blood to go down. In the second and more important part of what we did was to look at the lymph nodes. And what we saw in the lymph nodes was antibody producing cells in the germinal centers of the lymph nodes. And the germinal centers are kind of like training camp or school for B cells.

And what we saw that was sort of surprising was even 12 weeks after the vaccine had gone in the arm, we were still seeing in quite a few of those folks, we were still seeing these cells in the lymph nodes. And what's important about that is the lymph nodes are where your antibodies get better, right? Where they learn how to bind better, where they learn how to make a broader response to variance.

DR.JOHN WHITE: So what's the bottom line? Because some people are saying you can interpret this data even though it's based on 12 weeks that the durability the vaccine, the mRNA vaccines could provide protection for years. Is that what we can conclude, maybe even a lifetime for those people that have been previously infected with COVID.

DR.RACHEL PRETSI: Yeah, so immunology is still one of those fields where we know a whole lot more about what happens in animals than we do what happens to humans. But the whole point of the immune system is to make an immune response that lasts your whole lifetime. And so I think we get very focused on what's going on in the blood because that's easy to see, right?

But what your immune system is supposed to do when it sees a pathogen is it takes that to the lymph node, it makes a really strong immune response. And then after that, the really good cells will go to the bone marrow and they make those memory cells that are supposed to last you life.

So we're still trying to figure out the bone marrow part, we don't have that data yet but we should hopefully, have that soon. But what we're seeing in the lymph nodes is they're making a really good response. And I think that's promising that we might have a response that's going to last for a long time.

DR.JOHN WHITE: How long is a long time?

DR.RACHEL PRETSI: You know, we've only known about this virus for a year, actually a little bit more, well, a year and a half. So scientists don't like predicting the future but I think it's likely that this is going to be a durable immune response. Having yet to that is what is the virus going to do?

DR.JOHN WHITE: Sure, with the variants and mutations. But could one reasonably conclude, from your research that the vaccine effectiveness for the mRNA vaccines could last for years?

DR.RACHEL PRETSI: I think you could. I think it looks very promising that you at least make an antibody response that is likely to last for quite some time.

DR.JOHN WHITE: So there Presti, are a lot of people are excited about this research and it may show us that we don't need boosters, we need a little more time to tell. But others will say, Dr. Presti, it was a very small study. How do we know that this information is going to hold up?

DR.RACHEL PRETSI: This study gave us a tremendous opportunity that we haven't really had to see how does your immune system work to a new virus and to see it in extreme detail, right? So we were able to look in the blood but also in the lymph nodes and hopefully also in the bone marrow. And that's important data.

DR.JOHN WHITE: Well, some encouraging data about how long the mRNA vaccines may provide protection against Coronavirus. Dr. Presti, I want to thank you for the research that you're doing to help provide answers to the questions that we're all having.

DR.RACHEL PRETSI: Thank you very much.