3 doses of Pfizer vaccine neutralizes Omicron variant, suggest preliminary studies

As of Tuesday afternoon, B.C. had identified five Omicron cases in the province

A new study shows the benefits of having three doses of Pfizer's COVID-19 vaccine | Photo: Reshi Irshad / Getty Images

The drug and vaccine manufacturer Pfizer released preliminary data Wednesday indicating three doses of the Pfizer-BioNTech COVID-19 vaccine neutralizes the Omicron variant — a mutation of the SARS.CoV.2 virus that has spread to dozens of countries around the world and that scientists worry could prove more infectious and more resistant to vaccines.

The preliminary laboratory studies, which have not been peer reviewed, also indicate two doses of the Pfizer-BioNTech vaccine “may not be sufficient to protect against infection with the Omicron variant,” according to a statement from Pfizer Wednesday. 

Pfizer and BioNTech added that they believe those vaccinated with two doses “may still be protected” against severe Omicron infections.

“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 BioNTech CEO Ugur Sahin in a written statement. 

“Broad vaccination and booster campaigns around the world could help us to better protect people everywhere and to get through the winter season.”

Since Nov. 25, the companies have been working on an adapted vaccine that will give people a high and prolonged level of protection against the Omicron variant. They say they have “high confidence” it will be ready by March 2022 and expect to produce four billion doses.  

The latest human laboratory studies were conducted a month after participants were vaccinated with a booster dose of the vaccine. Those who had received three doses were found to have the protection against the Omicron variant at comparable levels to what has been observed in people exposed to “wild-type SARS.CoV.2” after two doses. That's largely due to a third dose of the mRNA vaccine triggering a boost in the immune system's T-cell response. 

Because the laboratory experiments are small and not conducted in the real world, they don’t provide conclusive evidence of how the vaccine will respond to the Omicron variant at the population level, where a wider range of immune responses can lead to different outcomes. Still, the preliminary results are a promising sign that booster dose campaigns will lead to stronger and more lasting protection, even against Omicron.

The Pfizer-BioNTech data come a day after B.C. provincial health officer Dr. Bonnie Henry said the Omicron variant had been identified in five people in British Columbia, as of Tuesday afternoon. 

In addition to the five cases already isolated in British Columbia, Henry said Tuesday that there are a number more "suspect and pending" confirmation.

The cases have all been found in people travelling to the province from places like Nigeria, South Africa and Iran — three who are fully vaccinated and two who are unvaccinated. Health authorities continue to conduct wastewater surveillance to assess the variants' community spread. 

Health Minister Adrian Dix said B.C. health authorities remain focused on the Delta variant, which still accounts for an overwhelming number of COVID-19 cases in the province.

Meanwhile, the province's booster dose campaign continues. Using a risk-based approach, the oldest British Columbians are being targeted first, followed by cohorts all the way down to 16 years old. Invitations for a booster dose are being sent out six months to eight months after an individual's second dose.

So far, over 500,000 booster doses have been offered in B.C., including at all long-term care facilities, said Dix.

Booster doses are also now being offered to those with compromised immune systems, as well as Indigenous, Métis and Inuit people.

Henry said there are still too few cases of Omicron in B.C. to gauge how it responds to COVID-19 vaccines.

The latest National Advisory Committee on Immunization recommendations — which call for booster doses for those 15 and older — align well with what B.C.'s vaccine campaign has been "thinking all along," added the provincial health officer.