Three doses of Pfizer-BioNTech COVID-19 vaccine neutralize Omicron variant, says study

A preliminary laboratory study demonstrated that three doses of the Pfizer-BioNTech COVID-19 vaccine neutralize the Omicron variant (B.1.1.529 lineage) while two doses show significantly reduced neutralization titers.

Pfizer Inc and BioNTech SE announced results from an initial laboratory study demonstrating that serum antibody induced by the Pfizer-BioNTech COVID-19 vaccine (BNT162b2) neutralize the SARS-CoV-2 Omicron variant after three doses.

Data indicated that the third dose of BNT162b2 increased the neutralizing antibody titers by 25-fold compared to two doses against the Omicron variant; titers after the booster dose are comparable to titers observed after two doses against the wild-type virus which are associated with high levels of protection, reported Pfizer and BioNTech press release on Omicron variant.

Sera obtained from vaccines one month after receiving the booster vaccination (third dose of BNT162b2 vaccine) neutralized the Omicron variant to levels that are comparable to those observed for the wild-type SARS-CoV-2 spike protein after two doses.

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, indicating that two doses of BNT162b2 may not be sufficient to protect against infection with the Omicron variant.

However, 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.

More robust protection may be achieved by a third dose as data from additional studies of the companies indicate that a booster with the current COVID-19 vaccine from Pfizer and BioNTech increases the antibody titers by 25-fold, added the release.

According to the companies' preliminary data, a third dose provides a similar level of neutralizing antibodies to Omicron as is observed after two doses against wild-type and other variants that emerged before Omicron.

These antibody levels are associated with high efficacy against both the wild-type virus and these variants. 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, the vast majority of these epitopes remain unchanged in the Omicron spike variant.

As 80 per cent of epitopes in the spike protein recognized by CD8+ T cells are not affected by the mutations in the Omicron variant, two doses may still induce protection against severe disease.

The companies continue to advance the development of a variant-specific vaccine for Omicron and expect to have it available by March in the event that an adaption is needed to further increase the level and duration of protection - with no change expected to the companies' four billion dose capacity for 2022, said the release.

"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 the third dose of our vaccine," said Albert Bourla, Chairman and Chief Executive Officer, Pfizer.

"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," added Bourla.

"Our preliminary, first dataset indicates that a third dose could still offer a sufficient level of protection from the disease of any severity caused by the Omicron variant," said Ugur Sahin, MD, CEO and Co-Founder of BioNTech.

"Broad vaccination and booster campaigns around the world could help us to better protect people everywhere and to get through the winter season. 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 disease as well as prolonged protection compared to the current vaccine," added Sahin.

The companies have also previously initiated clinical trials with variant-specific vaccines (Alpha, Beta, Delta & Alpha/Delta Mix) and data from these studies will be submitted to regulatory agencies around the world to help accelerate the process of adapting the vaccine and gaining regulatory authorization or approval of an Omicron-specific vaccine, if needed, added the release.

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.