How Effective Is the COVID Vaccine on Kids?

Pfizer and BioNTech announced today that they have completed a phase 3 trial of their COVID-19 vaccine in children aged 12 to 15, and that so far it seems to be 100% effective in that age group. If the FDA agrees that the vaccine is safe and effective, it might be available for ages 12 and up this summer.

What ages are authorized to use the vaccine?
The Pfizer vaccine is currently authorized for age 16 and up, and the other two U.S. vaccines (Moderna and Johnson & Johnson) for age 18 and up. All three companies have said they are testing or planning to test their vaccine in children. (Typically, a company will run trials on adults, then teenagers, then younger children.)

The recent trial was in 2,260 adolescents, of whom half got the vaccine and half got a placebo. There were 18 cases of COVID-19 in the placebo group, and none in the vaccine group, meaning that the efficacy worked out to a perfect 100%. In a real world use, that number might turn out to be lower, but to see that result is promising.

The investigators also tested the kids’ antibody levels one month after receiving their second dose, and found that they were as good as antibody levels of adults who were vaccinated. Side effects were similar to those observed in older age groups.

What comes next?
So far all we have is the Pfizer press release, but the company says they plan to publish the results in a peer-reviewed journal and also to submit them to the FDA. The FDA could, in turn, change the emergency use authorization (EUA) for the vaccine to make it available for people aged 12 and up, instead of the current 16 and up. (None of the vaccines are fully approved, but the EUA allows them to be legally administered during the pandemic.)

The company says that it has already started a trial in five to 11-year-olds, and that they will start administering doses to two to five-year-olds next week. Authorization for those age groups will probably not be possible until late this year or early next year.