Pfizer vaccine for young children back in clinical trial

Following a routine review by an external committee, Pfizer announced that the vaccine company will amend the clinical study of the Pfizer-BioNTech novel coronavirus (COVID-19) vaccine in children 6 months to under 5 years of age.

A third dose of three micrograms at least two months after the second dose of the two-dose series will now be evaluated in the study, according to an update from the company on December 17.

A pre-specified immunogenicity analysis was conducted on a subset of the study population one month following the second dose. Compared to the high efficacy demonstrated in the 16-to 25-year-old population, non-inferiority was met for the 6-to 24-month-old population but not for the 2-to under 5-year-old population in this study. According to Pzifer, no safety concerns were identified, and the three-microgram dose showed a favorable safety profile in children 6 months to under 5 years of age.

The company decided to evaluate a third dose of three micrograms for children in this age group to make sure it selects the right dose to maximize the risk-benefit profile. If the three-dose study is successful, Pfizer and BioNTech plan to submit data to regulators to support an Emergency Use Authorization (EUA) for children six months to under five years old in the first half of 2022.

The Phase 1/2/3 trial initially enrolled up to 4,500 children ages six months to under 12 years of age in the United States, Finland, Poland, and Spain from more than 90 clinical trial sites. The trial evaluated the safety, tolerability, and immunogenicity of the Pfizer-BioNTech vaccine on a two-dose schedule, approximately 21 days apart, in three age groups: ages 5 to 12 years; ages 2 to under 5 years; and ages 6 months to under 2 years.

Based on the Phase 1 dose, children ages 5 to under 12 years received a two-dose schedule of 10 micrograms each while children under age 5 received a lower three microgram dose for each injection in the Phase 2/3 study. The trial enrolled children with or without evidence of COVID-19 infection.