Drug makers Pfizer and BioNTech on Thursday said their COVID-19 vaccine was 91.3 per cent effective six months after taking the second dose.
Results from over 46,000 participants who took part in phase 3 trials confirm previously released data and demonstrate strong protection against COVID-19 through six months post-second dose, the companies said in a release.
"...the Pfizer-BioNTech COVID-19 vaccine, BNT162b2, was 91.3 per cent effective against COVID-19, measured seven days through up to six months after the second dose," it said.
The vaccine was 100 per cent effective against severe disease as defined by the U.S. Centers for Disease Control and Prevention (CDC), and 95.3 per cent effective against severe COVID-19 as defined by the U.S. Food and Drug Administration (FDA).
"A total of 697 cases of COVID-19 were observed in the US; 647 cases of COVID-19 were observed in the placebo group versus 50 in the vaccine group, indicating vaccine efficacy of 92.6 per cent," it said.
The vaccine was also effective in South Africa, where B.1.351 lineage of the virus is prevalent. It said nine cases of COVID-19 were observed in the country, all in the placebo group, indicating vaccine efficacy of 100 per cent.
"In an exploratory analysis, the nine strains were sequenced and six of the nine were confirmed to be of the B.1.351 lineage. These data support previous results from immunogenicity studies demonstrating that BNT162b2 induced a robust neutralising antibody response to the B.1.351 variant, and although lower than to the wild-type strain, it does not appear to affect the high observed efficacy against this variant," the release said.
The companies also said that there were no serious safety concerns in trial participants up to 6 months after the second dose and the side effects were generally consistent with previously reported results.
Pfizer Chairman and CEO Albert Bourla said the results would "position us to submit a Biologics License Application to the U.S. FDA".
"These data also provide the first clinical results that a vaccine can effectively protect against currently circulating variants, a critical factor to reach herd immunity and end this pandemic for the global population," BioNTech co-founder and CEO Ugur Sahin said.
The vaccine has been authorised for emergency use by FDA for individuals aged 16 years and above. It is based on BioNTech's proprietary mRNA technology, and was developed by both BioNTech and Pfizer.