The study will use participants from the Phase 1 study in the US, who received their first doses as of May last year. These participants received two 30μg doses; and will now receive a 30μg booster of BNT162b2 6-12 months after their initial two-dose regimen.
Meanwhile, Pfizer and BioNTech are in discussions with regulatory authorities, including the US Food and Drug Administration (FDA) and European Medicines Agency (EMA), to investigate a registration-enabling clinical study to evaluate a new vaccine, which would have a modified mRNA sequence to target a specific variant. This would be based on the South Africa B/1/351 lineage.
While in vitro studies suggest that the vaccine remains effective against the UK and South Africa variants, Pfizer says it is taking steps to ‘act decisively’ and be ready in case a strain becomes resistant to the vaccine.
It hopes that any future modified mRNA vaccines could benefit from a regulatory pathway similar to the existing approach for flu vaccines.
“This booster study is critical to understanding the safety of a third dose and immunity against circulating strains,” said Albert Bourla, Chairman and Chief Executive Officer, Pfizer. “At the same time, we are making the right investments and engaging in the appropriate conversations with regulators to help position us to potentially develop and seek authorization for an updated mRNA vaccine or booster if needed.”
Ugur Sahin, CEO and Co-founder of BioNTech, says the mRNA platform can be easily used against new variants if required. “The flexibility of our proprietary mRNA vaccine platform allows us to technically develop booster vaccines within weeks, if needed. This regulatory pathway is already established for other infectious diseases like influenza. We take these steps in order to ensure a long-term immunity against the virus and its variants.”