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How The COVID-19 Vaccine Trials In Children Are Going To Work


This week Moderna began testing its COVID-19 vaccine in babies and young children 6 months to 11 years old, and Pfizer will soon follow. Now, it could still be many months, even a year or more, before a vaccine for young children is authorized. But meantime, we wanted to know; what exactly are researchers trying to learn through these trials? And we put that question to Dr. Yvonne Maldonado of Stanford. She's chair of the American Academy of Pediatrics' Committee on Infectious Diseases, and she'll be involved in a couple of the Pfizer trials in children.

YVONNE MALDONADO: The little adage that we learn in pediatrics is that children are not little adults. And so you can't just downsize something to their weight or age. So you need to start off assuming that they will be very different, although the biological mechanisms should be very similar.

CORNISH: If COVID cases are down by the summer, could it actually take longer to get the sufficient data that you need from trials with young children?

MALDONADO: Well, it depends on how much information we have about the vaccines themselves from adults. And so the reason I say that is you can do the studies in a variety of ways. One would be to wait for enough cases, but the other study would be to look at an immune correlate, which would be, do the children make the same antibody levels as adults? And is that good enough to assure that there could be protection?

So we are going to be doing a combination. And I think the company will make a decision ultimately with the FDA on whether the immune correlates - that is, whether the children mount a good immune response at equivalent to adults - is good enough to approve the vaccines. And so that's where the discussions will be held.

CORNISH: By definition, a trial has risks. Can you talk about what some of the risks are here?

MALDONADO: Yeah. So the risks, of course - these are the - we're also going to be doing a second phase of studies, which will be dose finding, and these will be in the younger age groups - so going down to the 2- to 5-year-olds and then to the 6-month-old to 2-year-olds. And the idea there will be to start at a very low dose of vaccine and see if the children tolerate it. And by that, I mean, do they get high fevers? Do they get significant pain or swelling at the site of injection? Could they have other allergic symptoms that we're not aware of that might be different from what adults found?

And if they do experience more of those, then you might want not to go to the next higher dose, but you go to the higher dose that is well-tolerated. So, for example, a failure would be if you not only have higher side effects but you also don't get the same kind of antibody response as you would in adults.

CORNISH: I recall hearing at one point that - in terms of children who had actually died from COVID, that kids of color were disproportionately affected. So what does that mean as you're approaching a vaccine trial for young people?

MALDONADO: Well, you know, this happened during the HIV epidemic many years ago, and I worked through that. And I really - I have mixed feelings because I really don't want to brand our racial and ethnic minority populations as being at risk for certain things. It's not about race and ethnicity. It's social determinants of health and health equity. So I want to make sure we look at this through an equity lens and make people understand that their children may be at risk because of the conditions in which they might be living, not because of their race or their color. So that is really important to me personally. And I think to pediatricians in general, equity is critical.

CORNISH: Is this a hopeful moment to you?

MALDONADO: Well, I think the hopeful moment came last December, when the first vaccine was licensed. I thought that was almost a miracle to see a vaccine come out less than a year after we had even known this virus existed. So, yes, the vaccines to me are extremely hopeful. I - by training, I'm a vaccinologist. And I do believe that - we know that vaccines have prevented 75% of deaths in children around the world in the last 20 years. These are simple ways to do this, but they need to be done carefully with equity in mind and safety in mind, first of all. And so, yes, I am very hopeful.

CORNISH: That's Yvonne Maldonado, professor of pediatric infectious diseases at Stanford University, obviously a doctor as well.

Thank you for your time.

MALDONADO: Thank you so much for having me.

(SOUNDBITE OF HOWARD SHORE SONG, "DAYS OF THE RING") Transcript provided by NPR, Copyright NPR.