Let’s talk about AstraZeneca and Oxford University’s COVID-19 vaccine candidate and the big announcement that came out last week. I’m Dr. Jeff Kingsley and welcome to another edition of Riding in Cars with Researchers.

The announcement that came out last week is important to discuss because it has not yet been published and it has not yet been peer-reviewed. And the way the announcement was made was misleading. Or the way the media is discussing it is misleading. So the analysis was on tens of thousands of patients who had participated in this vaccine trial. When they analyzed the entire data set once patients had gotten the two-dose regimen and were already several months out from receiving those doses, a certain number of patients who were in the trial actually contracted COVID-19. At that point, they were able to look at that data and say, “Of the patients who got COVID-19, who got our vaccine and who didn’t?” If we look at that data and see that out of tens of thousands of people, a hundred patients contracted COVID-19 (let’s pretend all of those hundred patients did not get the vaccine). Then the vaccine’s efficacy would be deemed 100% – meaning zero patients who got the vaccine got COVID-19. And all of the patients who did get COVID in the arm that didn’t get the vaccine, that would be a 100% efficacy.

So what they published was that of their entire dataset there was about a 60% efficacy for their vaccine, but they announced that there was a small segment of the population that showed a 90% efficacy. Now that analysis isn’t justifiable. There were only 3,000 patients in that sub-segment, and the number of COVID-19 cases in that sub-segment wasn’t large enough to really rely on that analysis. And so you really can’t trust that that sub-analysis that talks about a 90% efficacy. You can rely on the analysis more that says a little more than 60% efficacy.

It’s still over the bar that we had created going into this. COVID-19 is scary. The bar for the vaccine candidates was set at 50% – meaning if you have a greater than a 50% efficacy, the FDA would consider approving your vaccine. And so 60% is still above that bar, but the 90% that they’re talking about in these sub-segments can’t be trusted as more analysis would be needed.

Thanks for riding along!

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