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Pfizer and BioNTech said Wednesday that their Covid-19 vaccine prevented symptomatic disease and was well-tolerated in a Phase 3 study of adolescents ages 12 to 15.

The companies say they will submit the data to the Food and Drug Administration as an amendment to the vaccine’s emergency use authorization, and will also submit the results to other regulators around the world.


Pfizer CEO Albert Bourla said in a press release that the companies hope it will be possible to begin vaccinating adolescents in this group before the beginning of the next school year.

The Phase 3 trial enrolled 2,260 adolescents who were randomly assigned to receive two doses of the vaccine or placebo. The main measure of the vaccine’s efficacy was whether a subset of subjects developed antibodies at the same level seen in older adolescents and adults. The antibody levels, expressed as SARS-CoV-2 neutralizing geometric mean titers, were 1,239.5, compared to geometric mean titers of 705.1 in subjects between the ages of 16 and 25 in previous studies. Those levels are considered non-inferior to one another.

But the vaccine also prevented symptomatic Covid-19 infection. There were 18 cases of Covid-19 among patients who received placebo and none in those who received the vaccine, the companies said.


Natalie Dean, a statistician specializing in vaccines at the University of Florida, said that the data on cases of Covid-19 is encouraging. “Considering that wasn’t even the primary aim, that’s a good amount of data because it’s coupled with the other information.”

The companies also said that the vaccine was well-tolerated, with symptoms similar in the 12 year-old to 15 year-old age group as among those aged 16 to 25. The vaccine is authorized in the U.S. for people aged 16 and older.

In December, Pfizer and BioNTech released side effect data from 100 adolescents in the 12 to 15 age group as part of the FDA’s review of the vaccine. One in five reported fever after their second dose, compared to none in the placebo group. More than a quarter reported having chills, compared to less than one in ten on placebo.

Pfizer and BioNTech announced last week that they had begun studies in children as young as six months, which will test whether lower doses should be used. Moderna is conducting separate studies in adolescents aged 12 years to 18 years and children aged 6 months to 12 years.

Nahid Bhadelia, an infectious disease physician and associate professor at Boston University School of Medicine, said the vaccine data are important because adolescents are at higher risk of getting Covid than younger children, and transmission among young people could continue even as adults become vaccinated.

Although she believes once adults are vaccinated, schools can be opened safely, she said a vaccine could provide another level of protection.

“Particularly if safety holds up, I think parents will see this as another valuable tool to keep their kids safe,” Bhadelia said.

The data were announced in a press release, with no information about the diversity of subjects in the study. The companies said they will submit the data to a peer-reviewed scientific journal.

  • This is very promising. The experts keep saying it’s safe for kids to go back to school, which in general is true. They have forgotten that there are students who cannot be lumped into one category because of medical conditions that make them more vulnerable. We have been hoping for this study to open up vaccinations for the most vulnerable students. Let’s get them all back into the classrooms safely.

  • In my urban California county, which had the possible benefit of getting the big outbreaks relatively late – this past winter mostly – the death rate among people under 30 is given as about 1 in 3,000 cases. I say benefit of getting the outbreaks late because some effective treatments were identified before our big surge, unlike the East Coast first wave, where doctors were flying blind, comparatively.
    With 1 in 3,000 cases being fatal, probably much less because many were asymptomatic – nearly all with health problems my kids do not have – I was pushing for a return to school, last fall certainly probably the data was available to open up last summer.
    But the variants are all worse. UK Kent variant is 3 times worse, roughly. If it is 1.7 times more contagious and 1.7 times more lethal – 1.7 x 1.7 -2.89 – about 3 times worse.
    More directly troubling – the news reports from Southern England and other places are of far more young people getting very seriously ill – though some of that may be due to other variants, there is not great typing in most cases. (UK is supposed to be best in world right now)
    There is a theory young people have immunity, learned immunity, to the original strain. If so, a variant could evade that immunity, whatever the reason, it is scary.
    But at least UK Kent variant does not evade vaccine induced or natural immunity, and by now about 1/2 of us are immune or partly immune from past infection or vaccination.
    Although they keep making hopeful claims, I see no clear proof our US vaccines are going to stop the South African or Brazilian variants.
    Moderna was reported to be beginning clinical trial enrollment for a “booster” – really a new vaccine – to stop the South African B1351 variant – disturbingly, to me at least, they are enrolling 210 people – so it appears to be a safety trial only. If the variants do evade our vaccines, the outbreaks from them will occur some time this summer – can anyone assure us their will be a modified vaccine available by then?

  • Good thing it is safe for adolescents because it wasn’t for my father (69) who died within 8 days of taking the vaccine. You won’t see any of the individuals whose deaths happened within a week of getting the vaccine in the news. It is possible that it is a coincidence until you start finding many others with similar experiences. If the companies were more transparent that there are significant risks including death I think it would be easier to trust they actually know what the outcomes from an experiment vaccine. To be clear I am not saying people shouldn’t get vaccinated merely that we should understand all of the risks up to death. To suggest it is 100% on anything should be a clear indication that someone either is fudging the numbers or didn’t do the rigiorous work.

  • No doubt, given that ‘vaccine nationalism’ is now the order of the day, this post won’t go down well in some quarters.
    But here’s an extract from an email from one of my neighbours who was a leading in-the-field medic in a number of previous vaccination programmes around the world.

    “ Any decision to vaccinate children is problematic. This illness is not generally deadly in children or even severe. Just about every other illness we vaccinate children against is dangerous to the child.
    So you are in as sense ” altruistically ” using children to protect more vulnerable people. We don’t yet know how significantly effective vaccinating children would be to stop transmission, so it’s not clear how much it would reduce infection rates.
    Better to let there be herd immunity developed in the very young, at least for now, and bash on with getting all the world’s most vulnerable vaccinated .
    That I think in the end will reduce global rates probably more than a few developed countries vaccinating their young to make themselves feel good! ”

    • I would agree with your post if not for the variants. There are reports of much more severe illness among young people when they are infected with the variants. There is also a theory young people’s protection from the virus is largely due to learned immunity – some claim from MMR vaccine – some claim from infection with an unidentified virus which causes only very mild disease.
      If something like that explains their protection, then a new form of the virus might be much more dangerous for them. Their immune system might not recognize it, and they might get as sick as much older people.
      Even the published findings on B1117 alone, that is, that is is about 3 times worse, and now the most common type in the US, could radically change the equation.
      Unfortunately, because the educational establishment would not be flexible, and find a way to get kids back in school last summer, and this fall, pretty safely, they missed a window they had, but now I think we have to wait to get more data.
      I realize this was not mostly about your post – to address that, if the new variants are a lot more dangerous for kids, I want my kids to get doses which would otherwise be sent overseas, even if their risk is still low – I can take less than 1 in 3,000 but 1 in 1,000 is too much, for example.

    • I should have said, variants escaping vaccines AND previous infection. I have read B.1117 is not known to infect people who got infected with our previous dominant strain, so are the outbreaks in New York, New Jersey and Michigan due to B1117 ? My guess is not.

    • I don’t know. Several factors to consider are (1) variants & children in Europe, (2) a successful vaccine surge in the US starting in May and (3) clinical trial data for that age group.

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