A Centers for Disease Control and Prevention panel has recommended the Pfizer COVID-19 vaccine for use in children as young as 12. The decision follows the Food and Drug Administration’s extension of the vaccine’s emergency use authorization for children 12 to 15 years old on May 10. 

The Ohio Valley ReSource asked Vince Venditto, an expert in vaccine design, about the Pfizer study data collected in participants ages 12 to 15. Venditto previously responded to listener questions about the safety and efficacy of the Pfizer and Moderna vaccines. 

ReSource: The FDA press release said that (the Pfizer vaccine) shouldn’t be given to anyone with a known history of severe allergic reaction, including anaphylaxis. Has that changed? 

Venditto: It’s really out of an abundance of caution. There are other options. So the allergic response to the Moderna and Pfizer vaccines — we think it’s due to a response to a specific component of the vaccine. So because the Johnson & Johnson vaccine is also available, people who have the anaphylactic response to Pfizer and Moderna would very likely not have the allergic response to Johnson and Johnson. I think it’s really out of an abundance of caution to make sure there’s not that risk there. I’m not aware of a change in the standards based on the FDA and the CDC. 

ReSource: In this latest trial of kids 12 to 15, were there any other risks associated with getting the vaccine?

Venditto: No. They are reporting about the same reactogenicity, so the same response that you get when you feel a little achy after the vaccine. So in children ages 12-15, they are reporting about the same response that way. They have a slightly better antibody response, so their immune system looks a little bit stronger compared to the 16 to 25 year-olds, but not really any major difference. And otherwise safe. Now this was only done in about a little more than 2,000 individuals and about 1,100 individuals got the vaccine. It’s smaller than the large-scale study that was done for the initial approval that had 40,000 people in it. So it is smaller, but everything looks like it’s working about the same in the 12 to 15 year-olds as it is in the older population. 

ReSource: This study seems small. But obviously it was large enough for the FDA to extend that emergency (use) authorization. Do you know why the study was this size?

Venditto: It has to do with the number of adults in the original study. And then based on the same safety profile, you’re basically running a smaller study just to determine if there’s anything coming up that is unexpected in a younger population. And you should see that in a thousand subjects, if something came up. But you know we have this safety profile in however many millions of adults that have received the vaccine — minus a few examples of anaphylaxis as the most common, rare side effect. The fact that we didn’t see anything in any of the children, it’s really just a continuation. There’s no reason to expect there to be any difference. But they are continuing to monitor the children long term, and so as they monitor the children long term, they’ll be able to still continue to assess safety just like they are in the adults as well. 

ReSource: And how long will they follow the children long term? 

Venditto: They are following them for an additional two years after their second dose. 

ReSource: The FDA release said the vaccine was 100% percent effective in preventing COVID-19. Does that mean the vaccine is more effective in children than it is in adults? 

Venditto: That’s a really difficult comparison to make. With the different size of the study, you’re comparing the 20,000 people who got the vaccine in the adult study compared to the 1,100 or so in this one. In the whole trial, which had 2,260 subjects, there were 18 cases of COVID-19. All of them were in the placebo group. And so that’s where this hundred percent comes from. Now, if you expand this number to 40,000, it’s very likely you’re going to have some number of cases in the vaccinated group. The only way to actually compare those is to do an equally sized trial. And so I suspect that after this is approved and after they start administering this to children on a large scale, we will probably see more information about the number of people who are vaccinated who are also getting infected. 

ReSource: The CDC also says that in general vaccine breakthrough cases are expected, and no vaccines are 100% effective at preventing illness. So should we expect breakthrough cases in the 12-15 year old age group?

Venditto: We should expect them the same way that we expect them in the adult population. I don’t think that there’s anything different about the 12 to 15 year olds. There’s nothing that I would anticipate that would say there was a difference. Just like in adults who have been vaccinated, some adults have been infected, and I think we should just be expecting the same thing to happen in children.

ReSource: Do we know anything yet about the study in children under the age of 12.

Venditto: I’m not aware of any data yet. I know that those studies are ongoing from both Pfizer and Moderna — they both have studies in younger children.  

The Pfizer COVID-19 vaccine study in children younger than 12 is ongoing. To find Pfizer vaccine, visit vaccine.gov

According to the Kaiser Family Foundation, there are nearly a million children aged 12 to 15 in the Ohio Valley: 231,000 in Kentucky, 589,000 in Ohio, and 82,000 in West Virginia.

This conversation has been shortened and edited for clarity.