A highlight from Coronapod: the biomarker that could change COVID vaccines

Nature Podcast
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In the show. We're going to bring you nature's take on the latest of it. Nineteen developments speaking to experts around the world about research during the pandemic. we're entering a new era. Now we've new covert strategies. There's some new eye knowns and we've got a vaccine hello and welcome to corona pod. I'm noah baker and joining me. This week is corona poed regular and calloway. And how how are you doing not bad. Thanks so you as ever at beavering away. Writing story after story after story about corona virus and the story. You're publishing this week is one. That's been quite a long time coming about correlates of protection. Now there's a lot to dig into here but to start with. Can you tell me what we mean when we say current surge protection. Yeah so it's looking at cove in nineteen vaccines or vaccines in general. And anytime you have a vaccine. Unless it's one hundred percent effective they're going to be people who get vaccinated and unfortunately still get infected on. The vast majority of people who are protected by the vaccine so quarrel protection is an immune measurement or some kind of measurement or biomarker. That tells you which is which which are going to be protected in which people might not be an. This is a really important and useful marker for immunologists people that are designing vaccines to know. Why what is it that so kind of coveted about this measure. Yeah it's really important critical. Perhaps and i think probably the most relevant application of knowing a core protection for who's vaccines is in the situation where we moved heaven and earth to conduct quite a large number of large field trials whether you give tens of thousands of people either a vaccine or placebo injection than you follow them to see who gets coded and who doesn't and that allows you to directly. Measure the effectiveness of a vaccine. But we're getting to a stage where it's harder to run trials involving thirty forty fifty thousand people either because covered nineteen vaccines are available or they're just too darn expensive and so we want to be able to take vaccines and give them to a smaller number of people and figure out whether they're likely to work or not right. So instead of giving a vaccine to tens of thousands of people and seeing how many people are protected. You look instead for some kind of biological marker be than antibody count or something which we know through these studies to provide a level of protection which is acceptable. Which is what you ultimately used to approve your vaccine exactly in almost all cases for vaccines for viruses. It is some antibody measurement saying you know people produce this level of antibody response. They have a strong likelihood of being protected. Probably not a guarantee you know. That's not how biology tends to work but know strong likelihood and regulators might be willing to say it good enough to deploy in the population provide. Of course it's safe. We're talking about a measure of efficacy. Not necessarily safety here right at the beginning of conversation. I this is a story. That's been a long time coming. Vaccines have been around for quite a while. Now and being being distributed a lot of data has been gathered and yet it's only now that we're starting to see the i kind of really clear data in humans to indicate what this corridor protection might be. Why is it taking so long. And what are we starting to see now. I mean there are a couple of reasons. The first one is is kind of a good one. I mean these these vaccines especially the first ones from visor. Madonna sam successful. It was hard to determine a corlett protection on them. Actually explain one of the most reliable ways that people do is they look in the clinical trial so a large field trial and they look at people who got vaccinated but still got infected. We call these breakthrough cases and they compare them to people who got vaccinated but it didn't get infected and you try and look at. What are the differences in their immune profiles an antibody levels or something like that to see if there's a clear threshold above which you get protection and below which you don't but you need a lot of these breakthrough infections to really get a clear picture of what protects you in what doesn't and with these first vaccines from fines there. Madeira they were so successful especially initially when they presented their first results that they just didn't have the data to to determine a coronado protection now. These trials have continued. They've had more and more breakthrough infections and they have gotten a clearer picture but making these measurements which are kind of measuring really precisely different kinds of antibodies. And maybe even other markers. It's not a simple matter. You know you have to do it in a very repeatable manner. You can't do it in labs all over the country you kind of want it done in the same facility or repeatedly in the same facility like different times. It's it's doing a lot of laboratory work on a lot of samples and then doing a lot of complicated statistics on them. And then checking your answer once twice three times. So that's why it's taking a while to get these answers and that's even more difficult to do when the thing that the vaccines are protecting against is also a moving target. When you have a vaccine is designed to fight one particular variant of the virus and others new variants that have arrived. It gets really tricky. To pick up. Are all of these reasons that people might have different immune responses different exposure. And so oh yeah. Completely described these breakthrough analysis as being the main way and i've heard him described as gold plated. But they're not the only way to come up with a corlett of protection another way that was done with meningococcal vaccines which has been immensely successful in developing new ones to say this trial was seventy percent effective. We're going to draw a line at seventy percent. It's like antibody responses and that's gonna be our threshold are correlated protection. It's worked pretty well for getting new vaccines in this category. So i mean there are other ways of doing this and you're right. It's a moving target and

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