Studies: Antibodies From 3 Doses of Pfizer-BioNTech COVID-19 Vaccine Neutralize Omicron

Pfizer and BioNTech SE have announced the publication of new results from 2 laboratory studies showing that 3 doses of the Pfizer-BioNTech COVID-19 vaccine (BNT162b2) elicited antibodies that neutralize the omicron variant, Pfizer said in a statement.

Data, which was published in the peer-reviewed journal Science, include readouts of sera data from 51 individuals who were vaccinated and received either 2 or 3 doses of the Pfizer vaccine, as well as a second study that evaluated the neutralization potential of serum antibodies from a subset of vaccinated individuals against the live virus.

Both data sets confirm previously announced initial study results showing that serum antibodies induced by the Pfizer vaccine neutralized the SARS-CoV-2 omicron variant after immunization with 3 doses.

By comparison, sera from individuals who received 2 doses of the COVID-19 vaccine showed limited neutralization titers against the omicron variant in both data sets, indicating that 2 doses of the vaccine may not be sufficient to protect against infection with the new variant.

However, based on observations that approximately 85% of epitopes in the spike protein recognized by CD8+ T cells are not affected by the mutations in the omicron variant, the 2 companies think that 2 doses may induce protection against severe disease.

Investigators analyzed a panel of 51 human immune sera obtained from the blood of individuals who received 2 or 3 30-µg doses of the COVID-19 Vaccine, using a pseudo virus neutralization test.

Additionally, data from a live virus laboratory study conducted with the University of Texas Medical Branch supports and extends these findings and was posted on the preprint server bioRxiv.

Investigators analyzed 4 panels that included human immune sera from the blood of individuals who had received 2 or 3 30-µg doses of the vaccine.

The first panel included sera from 20 individuals, collected 2 or 4 weeks after the second dose, while the second panel included sera from 22 individuals collected on the day of administration of a booster dose.

The third and fourth panels were collected 1 and 4 months after the third dose, respectively.

This study did not measure other immune indicators, including T cells and non-neutralizing antibodies.

Sera taken 1-month following a third dose showed a 22-fold increase in neutralization titers against omicron compared with titers just prior to the third dose when given, on average, 7.9 to 8.8 months after second dose, suggesting more robust protection against the new variant may be achieved with the current COVID-19 vaccine series, plus a booster dose.

The neutralizing titer levels against the omicron variant after immunization with 3 doses were like antibody titer levels after 2 doses against wild-type and other variants that emerged before the omicron.

Furthermore, from 1 to 4 months after a third dose, neutralization titers against wild-type and the omicron decreased by 1.6 and 2 times, respectively, suggesting similar waning for both variants.

All sera effectively neutralized the omicron variant at 4 months following a third dose.

Pfizer and BioNTech have put into place a booster research program to help ensure that the vaccine continues to offer a high degree of protection.

The companies intend to evaluate the efficacy and immunogenicity of the additional dose of both the current formulation and an omicron-based vaccine in a clinical setting.

The companies previously announced that they expect to produce about 4 billion doses of the Pfizer COVID-19 vaccine in 2022, and this number is not expected to change if another adapted vaccine is required.

Reference

Pfizer and BioNTech publish data from two laboratory studies on COVID-19 vaccine-induced antibodies ability to neutralize SARS-CoV-2 omicron variant

News release. Pfizer. January 24, 2022. Accessed January 24, 2022.