Pfizer's Chief Executive Officer Albert Bourla said the updated result, which includes data on more than 12,000 people fully inoculated for at least six months, positions the drugmakers to submit for full U.S. regulatory approval.
In a Phase 3 trial of 2,260 participants ages 12 to 15 in the USA, the vaccine elicited strong antibody responses one month after the second dose - exceeding those demonstrated in people ages 16 to 25 in previous trials, Pfizer reported.
The vaccine, given in two doses three weeks apart, is already cleared for emergency use in people ages 16 and up.
The trial reviewed more than 900 confirmed cases of Covid-19, most of which were among participants who received a placebo.
From the clinical trials that were performed, before the registration, it did not show any side effects. In the adult trial, side effects were generally mild-to-moderate and included injection-site pain, headaches, fever and fatigue.
As many as 52,86,132 HCWs and 39,75,549 FLWs have taken the second dose, the ministry said, adding that 4,29,37,126 beneficiaries above 45 years of age have been administered the first dose.
Pfizer CEO Albert Bourla
Those comparisons to the older population are important, because researchers are building off of the knowledge they gained in the adult trials.
'In South Africa, where the B.1.351 lineage is prevalent and 800 participants were enrolled, nine cases of COVID-19 were observed, all in the placebo group, indicating vaccine efficacy of 100%,' the company said.
The data from a clinical trial, which puts the shot ahead of other Western vaccine developers in the quest to protect children, will likely allow for its use in that group before the next school year, Pfizer Chief Executive Albert Bourla said in a statement.
Although the new study did not look at the Oxford University/AstraZeneca vaccine, Prof Moss said the evidence for the jab is that "it's very, very effective". "The initial results we have seen in the adolescent studies suggest that children are particularly well protected by vaccination, which is very encouraging given the trends we have seen in recent weeks regarding the spread of the B.1.1.7 United Kingdom variant".
Responding to the first study, the pharmaceutical giant said the data supports "previous results from immunogenicity studies demonstrating that (the vaccine) induced a robust neutralising antibody response to the (South African) variant".
Protection following the second dose of the two-shot Pfizer-BioNTech vaccine lasts at least six months, per an updated analysis of observations made in a phase 3 study.
Experts fear new variants of Covid-19 from South Africa and Brazil may be resistant to existing vaccines and treatment.