Pfizer and BioNTech have announced updated phase 2/3 trial results for their COVID-19 vaccine for children aged six months to four years.
The vaccine was given Emergency Use Authorisation (EUA) for this age group in June by the US Food and Drug Administration (FDA), and these updated trial results reinforce previously reported data that showed the vaccine to be safe and effective for this age group.
Participants in the study received a three-dose regimen of either the vaccine or a placebo. The results showed that the vaccine was 73.2% effective in protecting children aged six months to four years who hadn’t previously had COVID-19. This was based on 13 cases in the vaccine group and 21 cases in the placebo group, diagnosed from March to June 2022.
Albert Bourla, chairman and chief executive officer, Pfizer, said: “Building on the strong safety and immunogenicity data that led to FDA authorisation of our COVID-19 vaccine for children six months through four years, we are pleased to share confirmatory evidence that a full course of vaccination helps protect against symptomatic disease, particularly during a time when the Omicron BA.2 strain was predominant.”
Among children aged 6-23 months, the vaccine was 75.8% effective in preventing COVID-19, based on four cases in the vaccine group and eight cases in the placebo group, after 1.9 months of follow-up after the third dose had been given.
For children aged two to four years, the vaccine was 71.8% effective in preventing COVID-19, based on nine cases in the vaccine group and 13 cases in the placebo group, after 2.4 months of follow-up after the third dose had been given.
Pfizer noted that most of the positive cases were caused by the Omicron BA.2 subvariant, which was the dominant strain at the time, while BA.4 and BA.5 strains were emerging during the period of the study and efficacy results against these strains were inconclusive.
Consistent with their approach in adults, the companies are working with the FDA to prepare an EUA application for an Omicron BA.4/BA.5-adapted bivalent vaccine for children aged six months to 11 years.
The companies also outlined that an application for conditional Marketing Authorisation for this age group is being reviewed by the European Medicines Agency.