Study: 3 doses of Pfizer neutralize Omicron variant

Preliminary laboratory studies show that three doses of the Pfizer-BioNTech COVID-19 vaccine neutralize the Omicron variant, while two doses show significantly reduced neutralization titers, according to Pfizer.

Data indicate that a third dose of the Pfizer vaccine increases 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. Two doses may still provide protection against severe cases of the disease, but may not be sufficient to protect against infection.

Pfizer is working 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.

According to Pfizer, 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.

“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,” said Albert Bourla, chairman and CEO, Pfizer, 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.”

“Our preliminary, first dataset indicate that a third dose could still offer a sufficient level of protection from disease of any severity caused by the Omicron variant,” said Ugur Sahin, M.D., CEO and co-founder of BioNTech, in a statement. “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 a prolonged protection compared to the current vaccine.”

While these results are preliminary, the companies will 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 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.