Pfizer’s and BioNTech today said that they 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.
As seen in real-world data released from the Israel Ministry of Health, vaccine efficacy in preventing both infection and symptomatic disease has declined six months post-vaccination, although efficacy in preventing serious illnesses remains high. Additionally, during this period the Delta variant is becoming the dominant variant in Israel as well as many other countries.
"These findings are consistent with an ongoing analysis from the Companies’ Phase 3 study. That is why we have said, and we continue to believe that it is likely, 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," the companies said.
Just as Pfizer and BioNTech issued their plans, The Centers for Disease Control and Prevention and the Food and Drug Administration on Friday ssued a statement saying that fully vaccinated Americans do not need a booster at this time, but that people who are not vaccinated remain at risk of catching COVID-19, including the variants that are circulating. The agencies noted that along with the National Institutes of Health, they are engaged in a process to consider whether or when a booster might be necessary.
“The United States is fortunate to have highly effective vaccines that are widely available for those aged 12 and up. People who are fully vaccinated are protected from severe disease and death, including from the variants currently circulating in the country such as Delta. People who are not vaccinated remain at risk. Virtually all COVID-19 hospitalizations and deaths are among those who are unvaccinated. We encourage Americans who have not yet been vaccinated to get vaccinated as soon as possible to protect themselves and their community," the statement read.
The agencies noted that Americans who have been fully vaccinated do not need a booster shot at this time, and that FDA, CDC, and NIH are engaged in a science-based, rigorous process to consider whether or when a booster might be necessary.
"This process takes into account laboratory data, clinical trial data, and cohort data – which can include data from specific pharmaceutical companies, but does not rely on those data exclusively. We continue to review any new data as it becomes available and will keep the public informed. We are prepared for booster doses if and when the science demonstrates that they are needed," the agencies said.