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.