Canada OKs Pfizer’s bivalent booster targeting Omicron subvariants

Canada now has another weapon in its arsenal to fight COVID-19: Pfizer’s bivalent booster.

Health Canada announced Friday it has approved the updated shot, which has been designed to target Omicron’s BA.4 and BA.5 subvariants that are the dominant strains circulating in the nation at the moment.

It has been approved for Canadians ages 12 and older, and can be given at least three to six months following either the required two doses for full vaccination, or a booster shot. It is to be given in a 30 microgram dose.

The booster shot is the second bivalent vaccine to get federal approval after Moderna’s modified booster was authorized for use last month.

Pfizer’s shot also targets the original Omicron strain, Health Canada said in its regulatory approval. It said the BA.4 and BA.5 shot was authorized based on safety data obtained in clinical studies involving Pfizer’s first COVID-19 vaccine and original Omicron booster. Health Canada found the shot to provide “significantly higher responses” to the original Omicron virus when compared to Pfizer’s first vaccine. It is expected to have mostly mild side effects.

Pfizer said in a statement it’s planning to submit an application for its bivalent shot for children five to 11 to Health Canada for review. It did not give a timeline as to when it would be submitted. Health Minister Jean-Yves Duclos said Canada will get 2.8 million doses of Pfizer’s bivalent vaccine next week, and will have 11 million doses in total by the end of fall.

Health Canada relied on its “extensive experience” in strain changes for annual influenza vaccines when it reviewed Pfizer’s submission, said Dr. Supriya Sharma, chief medical adviser with Health Canada.

Pfizer’s submission included preclinical data obtained from animal studies that showed a booster dose of the BA.4/BA.5 bivalent vaccine triggered a strong immune response against Omicron subvariants BA.1, BA.2, BA.4 and BA.5 as well as the original strain of the virus, she said at a news conference.

“As part of our review, Health Canada also considered data on the safety and effectiveness of the original Pfizer-BioNTech COVID-19 vaccine, which has been safely administered to millions of people in Canada and around the world,” Sharma said.

“The vaccine safety profile is expected to be comparable to that of the original COVID-19 vaccines, for which a large amount of data is available. It’s worth noting as well that in the U.S., nearly five million doses of this new Pfizer-BioNTech bivalent vaccine have already been administered and no new safety signals have emerged.”

Vaccine effectiveness has taken a hit as the virus has evolved, and vaccine makers have had to work on creating new shots in an effort to boost protection levels. A bivalent vaccine is designed to target two different variants of the same virus.

Now that Canada has two bivalent vaccines on the market, the National Advisory Committee on Immunization (NACI) is “strongly recommending” bivalent vaccines be given as booster doses this fall.

In its own statement on Friday, NACI is strongly recommending Canadians 65 years of age and older, and individuals 12 years of age and older who are at increased risk of severe illness from COVID-19, be offered a fall COVID-19 vaccine booster dose regardless of the number of booster doses previously received.

All other individuals 12 to 64 years of age may be offered a fall COVID-19 vaccine booster dose, regardless of the number of booster doses previously received. However, Canadians 12 years of age and older who are not able or willing to receive a bivalent mRNA vaccine may be offered an original mRNA COVID-19 vaccine.

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In line with Health Canada’s regulatory approval, NACI recommended fall booster doses may be offered six months after a previous vaccine dose or six months after infection. It added a shorter interval of at least three months may be considered depending on heightened epidemiological risk, evolving epidemiology and “operational considerations for the efficient deployment of fall immunization programs.”

At this point in time, it is not expected that a booster dose be routinely provided every three months to Canadians, NACI said.

Canada will have enough supply of bivalent vaccines to meet demand this fall, said Dr. Howard Njoo, deputy chief public health officer of Canada, during the news conference.

“I know that some of you have already received an original mRNA vaccine for your fall booster. Evidence continues to show that original mRNA vaccines provide good protection against serious illness, and hospitalization, including from Omicron infection,” he said.

“If you recently received an original mRNA vaccine for your fall booster, you do not need to receive a bivalent Omicron targeting booster at this time.”

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Provinces and territories are currently rolling out bivalent booster shots designed to target more transmissible strains of COVID-19, including the dominant Omicron subvariants.

In August, the U.S. Food and Drug Administration authorized both updated COVID-19 booster shots. Regulators in the European Union and Japan have also approved Pfizer’s updated booster jab.

Last week, travel restrictions tied to the COVID-19 pandemic, including mask mandates, came to an end in Canada as the last remaining border measure officially ceased to be in effect. Travellers to Canada are no longer required to show proof of vaccination.

As of Oct. 1, there were 4,945 people hospitalized in Canada with COVID-19, with 298 in the ICU.