Pfizer and BioNTech have reported that a 10µg booster (third) dose of their Covid-19 vaccine demonstrated increased immune response in Phase II/III clinical trial in healthy children of the age five to 11 years.

The trial analysed the safety, tolerability and immunogenicity of the vaccine in children.

According to the positive data, a rise in SARS-CoV-2 Omicron variant and wild-type strain neutralising titers was reported on administering a booster dose vaccine versus the initial two doses. 

These findings support the potential function of a booster vaccine in preserving increased levels of protection against the virus in people of this age group.

In the Phase II/III trial, data were assessed from 140 children of the age five to 11 years who were given a booster nearly six months following the second 10µg vaccine dose of the initial two-dose regimen. 

Results from a subanalysis of 30 sera from the trial showed that serum antibodies elicited by a third vaccine could neutralise the Omicron variant in trial subjects, indicating a 36-fold rise in neutralising antibody titers versus those observed following the initial series.

Furthermore, a strong response was reported irrespective of the previous Covid-19 infection.

According to the immunogenicity data obtained from the 140 subjects in the trial with no evidence of prior infection, a six-fold rise in SARS-CoV-2 wild-type strain–neutralising geometric mean titers (GMTs) was seen a month following the booster versus the second dose of the initial series.

The vaccine was found to be well-tolerated without any new safety signals in the latest booster data readout from 401 subjects.

The companies intend to seek Emergency Use Authorization (EUA) from the US Food and Drug Administration (FDA) for the use of booster vaccine in children of the age five to 11 years soon. 

In October last year, the US FDA granted EUA for the use of two 10µg doses of the vaccine in this age group.

The companies initiated a trial assessing an Omicron-based Covid-19 vaccine candidate in healthy adults of the age 18 to 55 years, in January this year.