After their latest trial delivered disappointing results, Pfizer and BioNTech are ready to test if a third dose of their COVID-19 vaccine would trigger an immune response in very young children.
Pfizer and BioNTech are ready to test whether a third dose of their COVID-19 vaccine would trigger an immune response in very young children after their latest trial in kids under five years old delivered disappointing results.
Last week, the companies reported that their Phase I/II/III trial on 4,500 children under 12 years old found that while the vaccine appeared to have a positive effect on the immune response of those aged 6 months to 24 months, the same could not be said for those between two and five years of age.
No safety issues were observed in all ages under five years, which involved children from over 90 clinical sites across the U.S., Spain, Poland and Finland.
“While the study is ongoing and remains blinded, a pre-specified immunogenicity analysis was conducted on a subset of the study population one month following the second dose. Compared to the 16- to 25-year-old population in which high efficacy was demonstrated, 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 analysis,” the companies said in a statement.
For this reason, Pfizer and BioNTech are considering the administration of a third dose of 3 µg, similar to the first two doses, with the expectation that the third one would finally allow the drug to meet its immunogenicity endpoint. The proposed third dose, which still has to undergo a clinical evaluation, would be given at least two months after the second dose of the two-dose course.
Should this attempt succeed, Pfizer and BioNTech said they would immediately submit an application for emergency use authorization (EUA) with the U.S. Food and Drug Administration within the first six months of 2022.
The recommended dose for children under 5 years is 3 µg, while those aged under 12 years are to be given 10 µg. The companies are also reportedly evaluating the safety and immunogenicity of increasing the third dose for ages 12 to 17 years from 10 µg to 30 µg.
As of this writing, Pfizer-BioNTech’s COVID-19 vaccine is approved in the U.S. for ages 5 years and older, administered in two doses at least three weeks apart. In those above 12 years, a third dose may be given at least one month after the initial two-dose course in people who are immunocompromised. With regard to booster shots, those aged 18 years and up may have a single booster dose at least six months after the primary course.
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