The Pfizer-BioNTech Covid-19 vaccine is 91% effective in 5- to 11-year-olds, new study results show

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A 12-year-old in Los Angeles received a COVID-19 vaccine in May 2021.

  • Pfizer's vaccine was 91% effective in preventing symptomatic Covid-19 in 5- to 11-year-old kids.
  • The new results come from Pfizer's trial, which enrolled more than 2,200 children in this age range.
  • The FDA is reviewing Pfizer's application to offer its two-dose vaccine to younger children.
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The Pfizer-BioNTech coronavirus vaccine was 91% effective in preventing symptomatic illness in younger children, according to new study results released Friday.

The latest data comes as the Food and Drug Administration enters the final stages of reviewing Pfizer's application to offer its shot to 5- to 11-year-olds. Currently, the two-dose vaccine is OK'd for use in people 12 years and older. The FDA's expert panel is set to meet Tuesday to discuss and vote on Pfizer's application.

This is the first look at effectiveness data for Pfizer's vaccine in the 5- to 11-year-old age group. In September, the companies described immune responses from this study, but did not have enough Covid-19 cases at the time to calculate the vaccine's efficacy.

The results come from Pfizer's summary of its data submitted to the FDA. The results have been submitted to a medical journal but have yet to be published. The FDA will also publish its own review of the data ahead of Tuesday's meeting.

Vaccinated volunteers had fewer Covid-19 cases, reported less symptoms than kids who got placebo shots

Overall, the study tallied 19 Covid-19 cases, with 16 cases among those getting placebo shots and three cases in the vaccinated group.

The trial enrolled 2,268 volunteers, randomly giving two-thirds the Pfizer vaccine and the other third placebo shots. The study's population was about equally split by gender and was 79% white, 6% Black, 6% Asian, and 21% Hispanic.

While the case numbers are small, the three Covid-19 cases among the vaccinated group were mild with four or fewer symptoms, such as headache, cough, sore throat, and nausea.

Covid-19 cases among the placebo group had more symptoms. Eight of the 16 cases had five or more symptoms. Ten of these kids recorded fevers.

Across both the vaccinated and placebo groups, there were no severe Covid-19 cases and no deaths. The most common side effects from the shot were injection site pain, fatigue, and headache.

In its study in kids 5 to 11, Pfizer used a smaller dose than its original vaccine. While older children and adults receive two 30-microgram doses, these younger children were tested with two 10-microgram doses.

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