Pfizer's clinical trial for the third dose of the Covid vaccine for children under 5 years of age reports an efficacy of 80.5% with Omicron as the dominant variant.
Pfizer and BioNTech's Covid vaccine reports safety, immunogenicity, and efficacy results for phase II/III of its Comirnaty vaccine as third doses of 3 micrograms in children six months to five years.
Apart from a good safety profile and a good immune response, the efficacy reached 80.3%, according to the clinical trial involving 1,678 children who received the third dose at least two months after the second and at a time in which the circulation of the omicron variant predominated.
The immune response was measured one month after receipt of the reminder and compared with that obtained in those aged 16 to 25 years. Vaccine efficacy, a secondary endpoint in this trial, was 80.3% in children aged 6 months to less than 5 years. This descriptive analysis was based on 10 symptomatic cases of COVID-19 identified seven days after the third dose and accumulated through April 29, 2022.
The trial has had data from 10,000 children aged 6 months to less than 12 years in the United States, Finland, Poland and Spain and evaluated the safety, tolerability and immunogenicity of three doses of the vaccine in three age groups: from 5 to 12 years; from 2 to 5 years of age; and ages 6 months to less than 2 years. Based on the dose-escalation portion of the Phase 1 trial, children 5 to 12 years of age received a schedule of two doses of 10 µg each, while children younger than 5 years received a lower dose 3 µg per injection in the Phase 2/3 study. The trial enrolled children with or without prior evidence of SARS-CoV-2 infection.
The trial protocol specifies that a formal analysis will be performed when at least 21 cases have accumulated seven days after the third dose. Three 3 µg doses of the vaccine were well tolerated in this age group and no new safety signals were identified. Most adverse events were mild or moderate.
The final vaccine efficacy data will be shared once they are available and the companies will submit the scientific dossier to global regulatory authorities in the coming weeks to request approval for emergency use.