Pfizer and BioNTech announced results from an initial laboratory study demonstrating that serum antibodies induced by the Pfizer-BioNTech COVID-19 vaccine (BNT162b2) neutralize the SARS-CoV-2 Omicron variant after three doses.
The results, which are preliminary, have not been peer reviewed or published.
To conduct the analysis, Pfizer and BioNTech tested a panel of human immune sera obtained from the blood of people who received two or three 30-µg doses of the current Pfizer-BioNTech COVID-19 vaccine, using a pseudovirus neutralization test (pVNT). The sera were collected from peoples 3 weeks after receiving the second dose or one month after receiving the third dose of the Pfizer-BioNTech COVID-19 vaccine.
They found, on average, more than a 25-fold reduction in neutralization titers against the Omicron variant compared to wild-type virus in sera from people who had only a two-dose regimen. The companies said the results indicate that two doses of BNT162b2 may not be sufficient to protect against infection with the Omicron variant. However, they also said, “as the vast majority of epitopes targeted by vaccine-induced T cells are not affected by the mutations in Omicron, the companies believe that vaccinated individuals may still be protected against severe forms of the disease and are closely monitoring real world effectiveness against Omicron, globally.”
“A third dose also strongly increases CD8+ T cell levels against multiple spike protein epitopes, which are considered to correlate with the protection against severe disease,” they added.
On November 25, the companies started to develop an Omicron-specific COVID-19 vaccine, and if necessary, they can deliver the new vaccine, beginning in March 2022. The companies have previously announced that they expect to produce four billion doses of BNT162b2 in 2022, and this capacity is not expected to change if an adapted vaccine is required.
