INTERVIEW BY STEPHANIE DESMON
COVID-19 vaccinations for adults are already rolling out, but when can we expect vaccines to become available for children?
In this Q&A adapted from the March 4 episode of the Public Health On Call podcast, Stephanie Desmon turns to Kawsar Talaat, MD, who led one of Pfizer’s COVID-19 vaccine trials, to discuss when vaccines will become available for children, why vaccinating adolescents is important to population level immunity, and more.
I know that you have been involved in Pfizer vaccine trials for adults. I want to talk about children. Why are children not eligible for the vaccine at this time?
The people who are most vulnerable to severe disease from COVID have been adults, especially older adults and adults with preexisting conditions. So it was really important to get vaccines out as quickly as possible for that population.
Although kids can get and can transmit COVID, kids very rarely have severe disease, either with COVID or the post-COVID inﬂammatory disease called Multisystem Inﬂammatory Syndrome in Children, or MISC. It would be good to prevent disease in them as well, but when we make vaccines for children, we want to go a little bit slower, make sure that the vaccines are safe in adults, then go down in age to make sure that they’re safe and likely to be effective in younger and younger children.
Both the Pfizer and Moderna vaccines are now in clinical trials for adolescents ages 12 and older, and we should have some of those data in the next few months. Once these studies are completed, [there will be trials] with younger children. Hopefully over the next year or so we’ll have that safety data.
How soon could we see vaccines for adolescents?
I would think that in the next couple of months we’ll see some of the early data in that population. Hopefully by late spring or early summer we might have a vaccine authorized for adolescents, but [vaccines] may not be available for that age population until there’s a lot more vaccine available.
Do trials with children look different than they do in adults?
Yes. Children are a vulnerable population because they’re not yet at the age where they can provide informed consent on their own behalf, so they are protected by ethics codes in the Code of Federal Regulations. And our IRB [internal review board] is much more careful than [with studies on] adults, so we have diﬀerent rules for trials in children. If you do a vaccine trial in an adult, you just get the informed consent from that individual for their participation in the trial. But because children can’t provide that informed consent we have to get it from their parents.
If the child is old enough, we actually ask that they agree to participate in the trial. We make sure that they understand what the trial is for, that they understand all the processes and procedures that will occur in the trial, that they know that there’s going to be blood draws, for example. Because they can’t provide the consent, there are more safeguards to protect [them].
My 14-year-old is the size and shape of an adult. How come they’re not just little adults in this situation?
While they may be approximately the same size as an adult, their immune system is a little bit more robust than the immune system of an older person.
They may not need as high of a dose, depending on the vaccine.
Is it possible that an adolescent might need only one dose?
While they may have a robust response to the ﬁrst vaccine, it may not last as long and may not be as broad as the response they would have with two doses. If you look at the data from the vaccine studies that have been released so far, one dose is pretty protective, even in adults, but the second dose does a little bit better. We’ll probably see the same thing in children and adolescents, too—that one dose is pretty protective, but you’ll get a boosted response with the second dose.
My understanding is that kids need to be vaccinated going forward because without kids in the mix, we can’t reach herd immunity. Is that the case?
Right. If a virus enters a population where people don’t have immunity to it, the virus can easily transmit from person to person and make people sick, as we’ve seen with this new coronavirus. As more and more people are infected and develop immunity, the virus has a harder time ﬁnding people it can infect, so transmission will go down. And once you get to a high enough percentage of people who have immunity to that virus, then the virus can’t really transmit anymore. You can do this with natural infection, but in order to reach that level, we’d have to have so many more people get sick, so many more people end up in the hospital. We’ve lost more than 500,000 Americans to this virus and many, many more people all over the world, and that’s just too high of a cost.
So the best way to get that level of immunity is to vaccinate. You need a pretty high level of people who are vaccinated, somewhere upwards of 70% to 85%, and in order to reach that we need to vaccinate children and adolescents. It is possible for children and adolescents—even though the disease is relatively mild in them—to become infected and spread the virus to other people. And like I said, there are some children who get really, severely ill with this virus and some have even died. According to the CDC’s data, over 300 kids have died in the United States from COVID-19 infection, and that’s way too many children to lose.
I’m hearing a lot of talk of schools reopening. Obviously most of those children will not be vaccinated.
I think it is absolutely possible to send kids back to school without vaccinating them. You can do it safely if you adhere to very strict public health measures and if the circulation of the virus in the community is sufficiently low.
My kids are going back to school and they can’t wait. I can’t wait. Vaccinating kids gives us just one extra layer of protection. Again, they are not a priority group for severe illness, but as soon as we have enough vaccines available, we should absolutely vaccinate our kids so that the schools are safer and so they’re safer in school.
Kawsar Talaat, MD, is an assistant professor in International Health at the Johns Hopkins Bloomberg School of Public Health and works on clinical trials in the School’s Center for Immunization Research.
Stephanie Desmon is the co-host of the Public Health On Call podcast. She is the director of public relations and marketing for the Johns Hopkins Center for Communication Programs, the largest center at the Bloomberg School.