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In this video, Jeremy Faust, MD, of Brigham and Women's Hospital in Boston, discusses the important differences to consider when choosing between the Pfizer and Moderna COVID-19 vaccines for children ages 6 months to 5 years.

The following is a transcript of his remarks:

Hello, I'm Jeremy Faust, editor-in-chief of 番茄社区. Thank you for joining us.

Today, I would like to talk about I wrote in my newsletter over on Inside Medicine about the pediatric vaccinations just voted "yes" by the FDA for children 6 months and up. Both Pfizer and Moderna are getting the go ahead to move on to the CDC for final approval. This means that really, by the end of the month of June 2022, we will finally have vaccines for all ages across the spectrum, except for 0 to 6 months.

So number one, Pfizer and Moderna both are effective in preventing COVID-19. We see that symptomatic disease is prevented by both of them. The antibody levels met their prespecified goals, which implies very strong protection against severe disease. This is the immune-bridging strategy that's been talked so much about, that strategy using antibody levels to correlate to levels of protection against severe disease that has worked in older kids and teenagers so we know that that played out well. We are feeling confident that the antibody levels get us where we need to go.

The second question that people always ask: Is it safe? The answer is, it looks very safe. The levels of side effects were similar to the other age groups. We do not have a big enough trial to detect any cases of myocarditis, which has been detected primarily in teen and young adult males. That's good news.

The trial was big enough that if the rates were extremely high, we would see it. And we're reassured by the lower dose; we think that the lower dose for the toddlers and, quite frankly, the lower dose for the kids ages 5 to 11, has meant that the myocarditis rates have been lower in the 5-to-11 group where we already have a rollout. We think that'll be the same for 6 months up to 5 years, or in the case of Moderna, up to 6 years.

The next question that I'm getting a lot, especially as a parent, is: Between Pfizer's three-dose series and Moderna's two-dose series, which is better for kids under 5 years old'; for the littlest kids, the ones we're talking about. There's been this headline that's been around that would seem to suggest that Pfizer is better, and that's because Pfizer found in their interim analysis an 80% efficacy against symptomatic COVID in these 0- to 5-year-olds after the third dose.

Now, Moderna, for their part, they only have on average in the mid-40% efficacy range for the same question, so that would seem to suggest that Pfizer has this big edge over Moderna, but there are two reasons why I think they are probably quite similar.

The first is that Pfizer's 80% number wasn't really a prespecified interim analysis. They said 'We would do that analysis, looking at the efficacy on symptomatic disease, after a certain number of cases.' And they actually did this before that, because they wanted to get the FDA to look at the emergency use authorization, and they've met their endpoint goals on the antibodies. So this 80% number is kind of a little early; the confidence intervals are extremely wide, so much so as to make it almost unreliable.

In addition, there is this thing that a lot of us call a 'halo effect' or a 'honeymoon period,' which is that after the vaccine, there's this period where it's almost as if the recipient has what's called sterilizing immunity. That is, it's really hard to get infected with COVID in the first 5, 6, 7, 8 weeks after that vaccine because of the circulating antibodies.

Now that fades, and what's left over is a longer-term protection against severe disease, which is very important. But Pfizer looks like they did their little interim check right at the period, that point where the halo or honeymoon period was ending, and some infections in the intervention arm -- in the vaccine arm -- were starting to occur. I suspect that if we had a couple more weeks or a couple more months of data, that 80% efficacy would drop closer to Moderna's and they'd probably be considered similar.

On the other hand, Moderna has an advantage, and that's another reason why I think that these are kind of closer than people might realize, and maybe even Moderna is better. That is that Moderna is only a two dose series given 28 days apart. So, if you enrolled your kid to get Pfizer, they'd get a first dose and they'd get a second dose 21 days later, but they wouldn't be protected. Then 60 days after that, they'd get the third dose, and then another week after that is where the study data starts to be relevant.

So really, it takes up to 80 or 90 days for a child to have protection from Pfizer, whereas with Moderna, the doses are on the first day and the 28th day, and then 2 weeks later is when their data set starts to take off. Therefore, you could assume that 42 days after getting Moderna, the kid is protected.

Well, if you're a parent and you want your kid to be protected against SARS-CoV-2 by the first day of school this fall, Moderna's gonna get you there, but Pfizer will not, because for 40 some-odd days, the ones who got Pfizer don't have protection until that third dose. Whereas with Moderna, those kids got it pretty much right after that second dose.

I might choose, and I probably really will choose, Moderna for my 4-year-old because I just want her protected as soon as possible. But someone might say 'You know what? I think that in December or so, there's going to be another terrible surge, like Omicron, and we'll have a 100 times more cases than ever. I'd like my kid to have the maximum protection possible.' So for that reason, Pfizer is better because actually it starts working later, just in time for that surge. There's a little bit of gaming going on there, right? And we don't know what the future holds.

The bottom line is, I think that there are good reasons to give either one of them, and what's nice is we finally have options, whereas before we didn't. So that's the next move. For me, the real frontier is not convincing someone 'Pfizer or Moderna; Moderna or Pfizer.' The real challenge for all of us is to get parents to make that choice, to actually choose one of them, to choose vaccination.

We know in 5-to-11-year-olds, vaccine rates are just way low. They are still in the 30% range, and that's just very, very bad. That's because people don't understand that on the population level, COVID is causing a problem for kids.

What I think we need to do to move forward is just to speak the truth. Look, this [COVID] isn't the same for a kid as it is for an advanced senior citizen. Yes, that's true. And yet, it's so common a disease that we need to prevent it from happening as much as we can and prevent bad outcomes. That's where the vaccine comes in. We need to convince parents that it's necessary. We certainly need to talk about the safety profiles, and we'll continue to monitor that.

The last thing I'll say is that I think the way to get out of this period where we are so afraid of this virus is to maximize vaccination over time. We will see with better vaccinations, with better therapeutics, that COVID-19 won't be as fearful of a disease to get as it was a year ago, let alone now. I think that using these tools in our kit will actually do the thing that a lot of people want to do, which is to help us move on. We do that by making COVID into a 'shrug-off' event; no big deal. I think that we are closer to that than ever, but without vaccinating everybody, we will not reach that point.

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