Third dose bumps up efficacy of Pfizer-BioNTech's Covid-19 vaccine in youngest group of children to 80%
Pfizer and BioNTech said Monday that they’re ready to approach the FDA this week with early data for their booster shot for Covid-19 vaccine in the youngest age group (6 months to under 5 years), which showed 80.3% efficacy based on 10 symptomatic Covid cases identified beginning seven days after the third dose.
“The study suggests that a low 3-ug dose of our vaccine, carefully selected based on tolerability data, provides young children with a high level of protection against the recent COVID-19 strains,” Uğur Şahin, CEO and co-founder of BioNTech said in a statement. “We are preparing the relevant documents and expect completing the submission process to the FDA this week, with submissions to EMA and other regulatory agencies to follow within the coming weeks.”
The vaccine also proved to be as safe as placebo, Pfizer said.
The FDA is likely to offer a swift EUA to both Pfizer’s vaccine and Moderna’s two-dose Covid-19 vaccine for this youngest group of children within the next month or so, barring any last-minute concerns by FDA staff. After reviewing the applications, the agency said it will hold a joint advisory committee meeting for the two vaccines on June 15. And June 14 will be the new meeting date for the FDA and its advisory committee of external experts to discuss Moderna’s EUA request for 6 years through 17 years of age.
Once the apps are fully submitted and the meeting dates are finalized, the FDA will release its own analyses of the Pfizer and Moderna data no later than two business days before each meeting.
Late last month, Moderna completed the filing of its EUA application, previously announcing that its vaccine is 51% effective in children 6 months to 2 years of age and 37% effective in 2- to 5-year-olds. And while that sub-50% efficacy number may raise eyebrows, FDA’s Peter Marks has said that it’s OK as long as the efficacy is above 50% for the entire range of the application submitted (6 months to 17 year-olds).
Meanwhile, Pfizer and BioNTech’s trial is still wrapping up, with the protocol specifying a formal analysis will be performed when at least 21 cases have accrued from seven days after the third dose. Final vaccine efficacy data will be shared once available, Pfizer said.
In total, the partners’ Phase II/III trial included 1,678 children receiving a third dose of the 3-µg formulation at least two months after the second dose at a time when Omicron was the predominant variant.
The immunogenicity analysis of geometric mean titer ratio and sero-response rate was conducted on a subset of study participants one month following the third dose in children 6 months to under 5 years of age, compared to the second dose in the 16- to 25-year-old population. Pfizer said non-inferiority was met for both the 6- to 24-month-old population and the 2- to under 5-year-old population for both co-primary endpoints.
Three 3-µg doses of the Pfizer-BioNTech vaccine were well-tolerated in this age group, Pfizer added, noting that the majority of adverse events were mild or moderate.
The children who participated in the trial and received placebo are now beginning to receive their vaccines.
Editor’s note: Updated with more information on the new FDA advisory committee meeting times.