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Should Coronavirus Vaccine Trials Be Unblinded?


It took a lot to develop the two COVID-19 vaccines that are now being distributed in the U.S., including volunteers who agreed to participate in trials. Some of those study participants got a vaccine. Others got a placebo. Since the trials were double-blind, neither the volunteers nor the administrators knew who got what. And so now that the vaccines have received emergency approval, there's a question. Should volunteers who got the placebo be offered the vaccine? Should the studies be unblinded? When an FDA advisory committee dug into this question about the Pfizer and Moderna vaccines, Dr. Steven Goodman of Stanford School of Medicine presented, and he's with us now.


STEVEN GOODMAN: Hi, Ari - looking forward to the conversation.

SHAPIRO: To start, will you just briefly explain why trials are blinded in the first place? What's the point?

GOODMAN: Well, the main point is that when we ascertain the outcomes - and in this case, the outcomes were both safety, how bad people felt and exactly what symptoms they had afterwards, as well as the infection - that they're not affected by knowing whether they got the vaccine or the placebo. That is the injection that felt like a vaccine but wasn't.

SHAPIRO: Now, what's the argument for not giving everybody the vaccine right now? What knowledge might we potentially lose if the folks who got the placebo suddenly get vaccinated?

GOODMAN: Well, it isn't so much lose, but we won't learn some very important things as well or as fast as we could. And the things that we want to learn more about - and this is really critical - are, how long does the protection last? We don't know the efficacy in all sorts of subgroups - various ethnicities, the old, people who have other conditions. And the other issue is if people leave the study because they think it's all over, then our attempt to learn about long-term effects, both safety and efficacy, is greatly diminished. So it's really important that people stay in as long as possible and report their symptoms in as objective a way as possible.

SHAPIRO: So there's value in keeping this study going. But how do you weigh that against the ethics of denying a workable, effective vaccine to people who volunteered to be human subjects to develop that lifesaving vaccine?

GOODMAN: Well, that actually is not exactly the choice. There is a design that allows them to get vaccinated within the trial, just as they would be outside even before, and still remain blinded.

SHAPIRO: So you're saying there is a loophole here where you don't have to unblind the vaccine, and you can still give everybody who got the placebo a dose of the effective vaccine. Explain that.

GOODMAN: Yes. So the proposal is to do what we call a crossover, which is that everyone who has the placebo or who got the placebo is vaccinated, and they get their two shots. But to maintain the blind, the people who got the vaccine originally also get two shots. But this time, they get the placebo. And even though we're comparing now a vaccinated to a later vaccinated group, there's still many things that we can learn from that comparison. And if we unblind, they become more difficult to learn.

SHAPIRO: Now that you have lots of people all over the country getting this vaccine, could the study just shift to following what happens in the general U.S. population rather than these volunteers who got the injection before it was widely available?

GOODMAN: Well, in fact, the FDA is planning to do exactly that. But the problem is that the information you get from those sort of studies - and they're absolutely critical - is going to be much slower and much less valid or less precise than what we can get from the studies which are studying individuals and being followed very closely. So, yes, we will be following these on a population basis. But the quickest and the most valid way to get some of this information is to make the most of what happens in the trials and continue to observe them even under blinded fashion, even vaccinated, for as long as we possibly can.

SHAPIRO: That's Dr. Steven Goodman, associate dean and professor of epidemiology and medicine at the Stanford School of Medicine.

Thanks for talking with us today.

GOODMAN: Thank you. Transcript provided by NPR, Copyright NPR.