As part of Pfizer’s and BioNTech’s continued efforts to stay ahead of the virus causing COVID-19 and circulating mutations, the companies are expecting a third dose of clinical studies of COVID-19 vaccine in August 2021. 

Pfizer and BioNTech have seen encouraging data in the ongoing booster trial of a third dose of the current BNT162b2 vaccine. Initial data from the study demonstrate that a booster dose given 6 months after the second dose has a consistent tolerability profile while eliciting high neutralization titers against the wild type and the Beta variant, which are 5 to 10 times higher than after two primary doses.

The companies expect to publish more definitive data soon as well as in a peer-reviewed journal and plan to submit the data to the FDA, EMA and other regulatory authorities in the coming weeks. In addition, data from a recent Nature paper demonstrate that immune sera obtained shortly after dose 2 of the primary two dose series of BNT162b2 have strong neutralization titers against the Delta variant (B.1.617.2 lineage) in laboratory tests.

The companies anticipate that a third dose will boost those antibody titers even higher, similar to how the third dose performs for the Beta variant (B.1.351). Pfizer and BioNTech are conducting preclinical and clinical tests to confirm this hypothesis.

While Pfizer and BioNTech believe a third dose of BNT162b2 has the potential to preserve the highest levels of protective efficacy against all currently known variants including Delta, the companies are remaining vigilant and are developing an updated version of the Pfizer-BioNTech COVID-19 vaccine that targets the full spike protein of the Delta variant. The first batch of the mRNA for the trial has already been manufactured. The companies anticipate the clinical studies to begin in August, subject to regulatory approvals.

Based on the totality of the data we have to date, that a third dose may be needed within 6 to 12 months after full vaccination. While protection against severe disease remained high across the full 6 months, a decline in efficacy against symptomatic disease over time and the continued emergence of variants are expected. Based on the totality of the data they have to date, Pfizer and BioNTech believe that a third dose may be beneficial to maintain the highest levels of protection.