The companies have said that a third vaccine dose raised Omicron-fighting antibodies by 36 times in this age group.
In an analysis of 140 children with no evidence of prior Covid-19 infection, antibody levels against the original strain of the SARS-CoV-2 virus were six times higher one month after a booster dose than a month after the second vaccine dose.
Studies from the New York State Department of Health and the US Centers for Disease Control and Prevention found that the effectiveness of Pfizer’s vaccine for children ages 5 to 12 dropped substantially during the Omicron surge, falling from 68% to about 12% against Covid-19 infection. However, two doses continued to provide protection against more severe illness resulting in urgent care or hospitalizations.
More than 10,000 children between the ages of 6 months and 12 years are enrolled in Pfizer Covid-19 vaccine trials at study sites around the world. The companies expect to submit data from these trials focused on children younger than 5 in the coming months. That age group is the only one for which a Covid-19 vaccine has not been authorized in the US.
Pfizer and BioNTech said they plan to submit this data to the European Medicines Agency and other regulatory agencies for authorization in the coming weeks.
An initial two-dose series of the Pfizer Covid-19 vaccine was authorized in the US for 5- to 11-year-olds in October. Boosters are also available for kids 12 and older with certain kinds of immunocompromise conditions, as well as adults. Second boosters are authorized for anyone 50 and older.