A booster shot of the Pfizer/BioNTech Covid-19 vaccine provides sufficient protection against the omicron variant of the coronavirus, Pfizer and BioNTech announced Wednesday based on early results from an initial lab study of the variant, which also showed just receiving two shots of the vaccine may protect against severe illness from the variant, but may not sufficiently prevent infection.
The study found a third shot of the Pfizer vaccine showed a 25-fold increase in protection from omicron as compared with two doses of the vaccine, which is comparable to the protection two doses of the vaccine provides against the original “wild type” strain of the coronavirus without mutations.
Booster shots also “strongly [increase]” T cell levels that correlate with protection against severe disease, Pfizer and BioNTech said.
The lab data found only two shots of the vaccine “may not be sufficient to protect against infection with the Omicron variant,” but Pfizer and BioNTech said they “believe” those who have received only two shots “may still be protected against severe forms of the disease.”
The lab study looked at the vaccine’s effectiveness based on subjects who were three weeks out from receiving their second dose of the vaccine and one month from receiving the booster shot.
The results are still “preliminary,” Pfizer and BioNTech noted, and they are continuing to study the variant based on lab data and its real-world effectiveness.
“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,” Pfizer CEO Albert Bourla said in a statement Wednesday. “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.”
What To Watch For
Pfizer and BioNTech said Wednesday they are still developing an omicron-specific vaccine to protect against the variant if it’s found additional protection is needed, which the companies project should be ready by March.
The booster’s apparent necessity for protection against the omicron variant could change the definition of what it means to be “fully vaccinated,” as BioNTech CEO Ugur Sahin said during a press conference Wednesday that a sufficient vaccine regimen against the omicron variant should be considered three doses rather than two.
What We Don’t Know
How other Covid-19 vaccines perform against omicron. There’s still no clear evidence yet of how effective vaccines made by other manufacturers like Moderna, Johnson & Johnson and AstraZeneca are against the variant, though Moderna and Johnson & Johnson have also started work on omicron-specific forms of their shots. Moderna chief executive Stéphane Bancel has also floated that the company could potentially use a higher dose of its vaccine to combat omicron if evidence shows the current dose is significantly less effective.
The omicron variant was first discovered in southern Africa on November 24 and has so far been identified in dozens of countries and at least 17 states, spurring new travel restrictions and Covid-19 measures worldwide. The new strain has sparked fears about its potential evasion of vaccines given its high number of mutations, and Pfizer/BioNTech’s study marked the first clear evidence so far of how the variant may perform against the shots. Much about the variant still remains unknown, and while early signs out of countries like South Africa, Norway and the United Kingdom suggest omicron may be more transmissible but also produce milder symptoms than earlier strains of the virus, experts caution more evidence is needed before drawing conclusions about the variant.
This is a developing story.