Omicron partially evades protection from Pfizer-BioNTech vaccine
A third shot appears to protect against new strain
The omicron variant can partially evade the Pfizer-BioNTech vaccine, but people who receive a booster may still be well protected, the companies said Wednesday.
Pfizer and BioNTech announced its two-dose vaccine saw a 25-fold reduction in neutralizing antibodies against the omicron variant, but a third booster dose would likely make up the difference.
Three doses may provide a similar level of antibodies against omicron as two doses provided against the original Wuhan strain, the companies hypothesize. The data was collected one month after the booster was administered, likely at a high point of protection.
“We have a dramatic reduction in neutralization titers against the omicron variant,” said BioNTech CEO Uğur Şahin in a press conference Wednesday morning. “This data would predict that individuals who have two doses will not have significant prevention from infection.”
The data suggests the vaccine should be a three-dose regimen, Şahin said.
However, T-cells, which are more durable than neutralizing antibodies, remain protective against severe disease caused by the omicron variant even after two doses, Şahin said. The vast majority of the epitopes in the spike protein of omicron are still recognized by key T-cells, according to BioNTech.
The companies conducted the tests in the laboratory using about 20 blood samples of people who had been vaccinated with two or three doses and tested how well they neutralized a pseudovirus approximation of the omicron variant. More lab studies are expected against a live omicron virus, which is more accurate.
The preliminary lab data shared on Tuesday do not provide enough evidence to suggest whether or not an omicron-specific vaccine is needed, which will be influenced by real-world data. Such data is not yet available, but could become available in the next six to eight weeks, according to Şahin.
Pfizer CEO Albert Bourla said at a public event this week that real-world data from countries with strong surveillance systems like Israel would be needed to confirm the results of studies in the lab.
The companies are continuing to monitor real-world efficacy, as are the National Institutes of Health, Centers for Disease Control and Prevention and the Food and Drug Administration.
If health officials determine omicron-specific vaccines are needed, they could be ready to deploy by March, according to the companies.
Omicron first alarmed global health officials when researchers in Botswana and South Africa found it had many more mutations on the spike protein targeted by vaccines than prior variants, and that many of those mutations were in places associated with increased transmissibility and severity. The variant has taken hold in a region of South Africa that previously saw a severe delta surge, suggesting it evades prior infection.
The companies’ announcement follows a similar laboratory study conducted by the Africa Health Research Institute and published on a preprint server Tuesday afternoon that suggested a more dramatic reduction than the companies found — a 41-fold reduction — in neutralizing antibodies caused by omicron.
The paper states that omicron does not completely evade vaccine-acquired immunity in people who also had a prior infection, so-called “hybrid immunity.” The researchers also stated that people with hybrid immunity are likely to be protected against severe disease from the omicron variant.
A leading researcher who worked on the paper said he was relieved the omicron variant had not mutated so much that it infected human cells in a novel way. Omicron infects human cells by targeting the same entry point as the original virus, the ACE2 receptor.
"Importantly, most vaccinologists agree that current vaccines will still protect against severe disease and death in the face of omicron infection. It's therefore critical that everyone should be vaccinated," said Willem Hanekom, director of the Africa Health Research Institute, in a statement.