Pfizer-BioNTech Reports Strong Immune Response to Booster Dose in Children 6 Months to Under 5 Years

Companies say the 3 doses of their vaccine meet all immunobridging criteria required for the Emergency Use Authorization (EUA).

Pfizer-BioNTech said a third dose (booster) elicited a strong immune response, with a favorable safety profile similar to placebo, in children ages 6 months to under 5 years old.

“These topline safety, immunogenicity and efficacy data are encouraging, and we look forward to soon completing our submissions to regulators globally with the hope of making this vaccine available to younger children as quickly as possible, subject to regulatory authorization,” Pfizer CEO Albert Bourla, said in a statement.

The vaccine’s efficacy was 80.3% with three doses during a period when Omicron was the predominant variant.

In the phase 2/3 trial, 1678 children received a third dose of the 3-µg formulation at least 2 months after the second dose. The immunogenicity analysis of geometric mean titer (GMT) ratio and seroresponse 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.

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.

According to the 2 companies, three 3-µg doses of the Pfizer-BioNTech vaccine was well-tolerated in this age group, and no new safety signals were identified. The majority of adverse events were mild or moderate.

The companies plan to submit these new safety, immunogenicity, and vaccine efficacy data on 3 doses to the Food and Drug Administration on its rolling US EUA application this week.

“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,” BioNTech CEO and Cofounder Ugur Sahin, MD, said.