In a widely expected move, the Food and Drug Administration has expanded its emergency use authorization for Pfizer (PFE 0.11%) and BioNTech's (BNTX 2.23%) COVID-19 vaccine to include people as young as 12 years old.

The widened authorization for BNT162b2 was based on the ability of the vaccine to induce the production of COVID-19 antibodies; the levels of antibodies it generated in clinical trial participants ages 12 through 15 were at least as good as the antibody levels in participants in the 16-to-25 age range.

Those antibodies appear to protect patients from being infected by the coronavirus.

Measured starting one week after they received their second doses of BNT162b2, none of the 1,005 adolescents who were inoculated developed COVID-19. Among the 978 trial participants who received placebo shots, there were 16 cases of COVID-19. That equates to a finding of 100% protection, although the numbers in the study were relatively small.

Healthcare worker giving an injection into the shoulder of a patient

Image source: Getty Images.

The side effect profile for the adolescents was similar to that seen in those 16 and older. In both groups, people had more side effects after the second dose than the first dose.

Pfizer and BioNTech beat Moderna (MRNA 3.06%) to the finish line in terms of gaining FDA authorization for their vaccine to be administered to adolescents. However, BNT162b2's period of exclusivity in that demographic, which presumably will only last for a couple of months, isn't likely to be much of a financial advantage. Large sales contracts with the U.S. government are already in place for both mRNA vaccines, so opening the use of BNT162b2 to a wider age group won't increase its sales. Until another vaccine is authorized for adolescents, some of Pfizer's doses will be used for adolescents, and any supply tightening that might cause for the adult demographic will be filled by Moderna's vaccine or Johnson & Johnson's.