Data indicate that a third dose of the Pfizer-BioNTech vaccine, BNT162b2, increases the neutralizing antibody titers by 25-fold compared to 2 doses against the Omicron variant.
This morning, Pfizer and BioNTech announced results from a laboratory study demonstrating that serum antibodies induced by their COVID-19 vaccine neutralized the Omicron variant after 3 doses. Sera obtained from vaccines 1 month after receiving the booster vaccination neutralized the Omicron variant to levels that are comparable to those observed for the wild-type SARS-CoV-2 spike protein after 2 doses.
The companies pointed out that as 80% of epitopes in the spike protein recognized by CD8+ T cells are not affected by the mutations in the Omicron variant, 2 doses may still induce protection against severe disease. However, the booster dose appears to increase protection significantly.
“Although two doses of the vaccine may still offer protection against severe disease caused by the Omicron strain, it’s clear from these preliminary data that protection is improved with a third dose of our vaccine,” Pfizer CEO Albert Bourla, said in a statement. “Ensuring as many people as possible are fully vaccinated with the first two dose series and a booster remains the best course of action to prevent the spread of COVID-19.”
The companies’ said the results are preliminary, and they are continuing to collect more lab data and evaluate real-world effectiveness to assess and confirm protection against Omicron and inform the most effective path forward.
In late November, the companies started to develop an Omicron-specific COVID-19 vaccine. They said the first batches of this vaccine could be ready for deliveries within 100 days, pending regulatory approval.