3rd Comirnaty Vaccination Neutralizes SARS-CoV-2 Omicron Variant

New York-based Pfizer Inc. and its vaccine development partner BioNTech SE today announced results from an initial laboratory study demonstrating that serum antibodies induced by the Comirnaty Pfizer-BioNTech COVID-19 Vaccine (BNT162b2) neutralize the SARS-CoV-2 Omicron variant after three doses.

Sera obtained from vaccinees one month after receiving a third Comirnaty vaccine dose neutralized the Omicron variant to levels comparable to those observed for the wild-type SARS-CoV-2 spike protein after two doses.

The companies stated the 'Sera from individuals who received two doses of the current COVID-19 vaccine did exhibit, on average, more than a 25-fold reduction in neutralization titers against the Omicron variant compared to wild-type.'

'This (data) indicates that two doses of BNT162b2 may not be sufficient to protect against infection with the Omicron variant.'

'However, ...the vast majority of epitopes targeted by vaccine-induced T cells are not affected by the mutations in Omicron.'

And the companies believe that vaccinated individuals may still be protected against severe forms of the disease.

According to the companies' preliminary internal data, 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.

Compared to the wild-type virus, most of these epitopes remain unchanged in the Omicron spike variant.

Known globally as Comirnaty, the vaccine is a nucleoside-modified RNA formulated in lipid nanoparticles and encodes an optimized SARS-CoV-2 full-length spike protein antigen. 

"Our preliminary, first dataset indicates that a third dose could still offer a sufficient level of protection from (COVID-19) of any severity caused by the Omicron variant," said Ugur Sahin, M.D., CEO and Co-Founder of BioNTech, in a press release issued on December 8, 2021. 

"We continue to work on an adapted vaccine which, we believe, will help to induce a high level of protection against Omicron-induced COVID-19, as well as a prolonged protection compared to the current vaccine."

On November 25, 2021, the companies started to develop an Omicron-specific COVID-19 vaccine.

While these results are preliminary, the companies stated they would continue to collect more laboratory data and evaluate real-world effectiveness to assess and confirm protection against Omicron and inform the most effective path forward.

The Comirnaty vaccine was issued the first U.S. FDA and WHO authorization to prevent severe COVID-19 in late 2020.