TORONTO -- It’s been more than one week now since the first cases of the Omicron COVID-19 variant were detected in Canada. While the government has been swift to react, much still remains unknown about the new variant, including its transmissibility and the severity of disease.
Questions also remain about the effectiveness of vaccines in protecting against Omicron, including booster shots. But for those considering holding off until more information or even a new vaccine is available, Chief Public Health Officer Dr. Theresa Tam advises against this.
“The extent of the protection against Omicron from the primary series and booster dose remains to be seen, and we're going to learn a lot about this in the days to come,” she said during a news conference on Friday. “But nevertheless, it is still prudent to maximize the possibility of protection from vaccine by, first of all, offering the vaccine to anyone who hasn't had the primary series, but then offering the boosters.”
On Friday, the National Advisory Committee on Immunization announced it strongly recommends that adults aged 50 and older receive a COVID-19 booster shot. The committee also made a discretionary recommendation on booster shots for Canadians 18 to 49 years of age, saying they “may” be offered a third dose based on individual risks and where they live. Tam said these recommendations would have been made with or without the presence of the Omicron variant.
One of the key factors behind this recommendation is the prevalence of Delta cases in Canada, said Tam. For months now, this variant has continued to account for the majority of daily new cases across the country. According to the World Health Organization, Delta is also the dominant COVID-19 variant worldwide.
“At this current moment, the Delta variant is the most dominant variant; it [accounts for] 99.8 per cent of what we have in Canada,” Tam said. “We have to mitigate the risk of this present threat.
“Right now, we have the potential for a Delta surge.”
OMICRON 'UNLIKELY' TO MAKE CURRENT VACCINES OBSOLETE
Dr. Susy Hota, medical director for infection prevention and control at the Toronto-based University Health Network, echoes this message, encouraging eligible residents to get their third dose.
“When you become eligible for a booster shot, you should go ahead and get it,” she told CTVNews.ca in a phone interview. “It's definitely worth getting whatever protection is conferred by those vaccines.”
The Omicron COVID-19 variant has more than 30 mutations of the spike protein, the part of the virus that attaches to human cells in order to infect them, Hota explained. While not yet confirmed, there are concerns that these mutations might increase transmission or make Omicron more infectious. Vaccine manufacturers themselves continue to wait for data on the effectiveness of their formulas in protecting against Omicron.
While there is a good chance current vaccines may not be as effective against the Omicron variant, Hota said they are still likely to offer some level of protection given their role in helping the body develop antibodies and T-cells to fight off the virus.
“It's very unlikely that it's going to completely make our current vaccines obsolete,” she said. “They may be reduced in effectiveness, but there's still a very broad immune response that these vaccines elicit.
“If we can increase the overall protection, it just puts us in a better place with all the variants that we're dealing with.”
VACCINE DEVELOPMENT & BOOSTER ELIGIBILITY
Another important thing to consider, said Hota, is the amount of time it could take to create a new vaccine that specifically targets the Omicron variant. If an entirely new formula is necessary, Hota said it could take months before the world sees a new vaccine, factoring in its development, experiments, regulatory approvals and manufacturing.
Pfizer and BioNTech, for example, have said that it would take about 100 days to develop a new vaccine and ship it out.
“My assumption is that's going to be months down the road and in the meantime, we could be facing a real threat,” Hota said. “I do think it's important to get the boosters if we're thinking about Omicron alone, sooner rather than later in case it…takes off rapidly, like what we've seen in other jurisdictions like South Africa.”
Alberta is one of the latest provinces to expand its booster eligibility, announcing third doses would be made available to all adults in stages. As of today, residents aged 60 and older are eligible for their third dose.
"The current evidence supports expanding booster doses to add an additional layer of protection," said Dr. Deena Hinshaw, Alberta’s chief medical officer of health, last week.
The Ontario government also announced that residents aged 50 and older will be eligible for a third dose starting in mid-December.
Additionally, Hota points to a period of about seven to 14 days before booster shots offer optimal protection. With this in mind, staying protected is key, she said, and the best ways to do this are by wearing a mask, avoiding large gatherings, getting vaccinated and if eligible, getting a booster shot.
“We can't really think about these things in isolation, we're still in a pandemic,” she said. “Regardless of what variant it is, these vaccines can be beneficial.”
COVID-19 booster shots contain the same formula as regular vaccines; the only difference is in the dosage of the Moderna booster vaccine. Both initial shots of Moderna contain 100 micrograms each. When given as a booster, adults age 70 and older, as well as those living in long-term care homes for seniors and other congregate living settings, will receive another dose of 100 micrograms. Anyone younger than 70 will be given a half-dose, or 50 micrograms, as a booster.
Meanwhile, the two initial shots of Pfizer-BioNTech contain just 30 micrograms of vaccine, the same amount included in a Pfizer-BioNTech booster shot. Guidance from NACI suggests that mRNA vaccines, such as Pfizer-BioNTech and Moderna, are preferred for booster shots. They’re also the only vaccines approved for use as a booster in Canada so far.
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