COVID bivalent vaccine: what you need to know about the new booster

Canadian citizens are required by the country’s federal, provincial and territorial governments to receive one of the two approved COVID-19 vaccines as soon as they are eligible.

Immunity conferred by vaccines weakens over time, so boosters are important when: continue to protect the population In response to COVID-19, health officials say particularly cool weather could lead to a surge in cases.

New shots by Moderna and Pfizer have been approved by Health Canada. September 4 When October 7and offer broader protection against COVID-19 and its subspecies than previous versions of the COVID-19 vaccine, the federal government said.

Bivalent vaccines target two different viruses or two strains of the same virus. In this case, the updated Pfizer-BioNTech Comirnaty vaccine not only killed the original SARS-CoV-2 virus, but also Omicron BA.4 and BA.5 subvariants, was known to be resistant to previous versions of the vaccine. Meanwhile, the latest Moderna Spikevax vaccine targets the original strain of the COVID-19 virus and the Omicron BA.1 variant.

The vaccine is manufactured using the same methods as previous COVID-19 vaccines, except that it contains: Two messenger RNA (mRNA) components This allows you to target multiple strains of the virus.

CTVNews.ca provides answers to some questions about new vaccines.

Who is eligible for a bivalent booster?

Health Canada has approved Moderna’s bivalent vaccine for ages 18 and over and Pfizer BioNTech’s vaccine for ages 12 and over, although provinces and territories have approved vaccines based on supply or prioritization of population needs. , may choose to further restrict eligibility rules.

For example, Ontario residents are eligible to receive a bivalent booster at least 3 months after their last dose. However, state health officials recommend that residents receive bivalent boosters. 6 months after last dose.

People at high risk of developing severe COVID-19 illness – including those aged 65 and over. Indigenous, Inuit, Metis. Those with underlying medical conditions; those who are pregnant, and those living in long-term care or collective care settings are eligible at 3-month intervals.

Both vaccines are offered only as boosters, so only people who have already completed the primary dose of the COVID-19 vaccine are eligible to receive it.

What is the difference between MODERNA and PFIZER bivalent boosters?

There are some minor differences between the two vaccines, explains Kelly Grindrod, a researcher and professor of pharmaceutical innovation at the University of Ontario Pharmacy.

“Moderna and Pfizer are pretty similar,” Grindrod told CTVNews.ca in an email on Friday.

“The Moderna vaccine has a slightly higher dose and is based on the original virus and the Omicron BA1 variant. Pfizer has a slightly lower dose and is based on the original virus and the Omicron BA4 and BA5 variants.”

According to Health CanadaThe Moderna vaccine is given in a dose of 50 micrograms, while the Pfizer BioNtech vaccine is given in a dose of 30 micrograms.

Can people mix and match bivalent boosters?

Grindrod, who also teaches at the University of Waterloo, said he mixed and matched the doses of the bivalent booster, just as he had no problem mixing dosing schedules involving previous Pfizer and Moderna vaccines. He said there was no problem.

“You don’t have to keep getting the same brand for a vaccine. This is similar to how other vaccines get where the brand used each year is mostly related to availability,” she said. “It’s best to pick the booster that’s most accessible, such as your nearest clinic or pharmacy.”

This is consistent with Health Canada’s guidance on co-dosing schedules for mRNA vaccines.

The latest guidance on the bivalent COVID-19 vaccine, released on October 7, states: The National Advisory Committee on Immunization wrote: “The immunological benefit and safety profile are likely to be similar in individuals who received a bivalent omicron-containing mRNA COVID-19 vaccine as a booster dose, regardless of the number or type of previous doses received. .”

Are the side effects different for each?

Side effects should be similar for both bivalent vaccines, and Health Canada reports they should be similar to those associated with previous versions, Grindrod said.

Responses to vaccination vary from person to person, but redness, pain, and swelling at the injection site are common symptoms, while chills, fatigue, joint pain, headache, low-grade fever, and muscle aches are common general symptoms.

These symptoms usually last hours to days after vaccination. This indicates that the body is responding to the vaccine and building immunity against the disease. Public Health Canada.

“Get up-to-date information on recommended vaccinations, including booster doses, even if temporary side effects occur,” says the agency’s “COVID-19: Vaccine Safety and Side Effects” web page. is displayed.

“This will help protect you from the serious consequences of COVID-19.”