Those over 80 advised to get booster shots
Anyone who got only AZ should also get third jab, advisory board says
Those over 80, adults living in long-term-care homes, and people who only got AstraZeneca shots could be offered a third COVID-19 vaccine dose, Canada’s national advisory body said Friday.
The first national recommendations for so-called booster doses set out guidelines for a practice already being undertaken by some provinces, whose health officials have said those at highest risk of a breakthrough case of COVID should be offered another shot.
The new statement from the National Advisory Committee on Immunization (NACI) says third doses should be offered — a minimum of six months after a person’s second — to seniors, but should also be an option for groups at high risk of illness or waning protection, including those who only got AstraZeneca doses, some front-line health-care workers, and adults in First Nation communities.
NACI is a panel of experts tasked with providing advice on immunization, though the final decision about who will be offered which vaccine rests with the provinces.
The case for booster shots, also sometimes referred to as third doses, is straightforward — with some fearing immunity will begin to ebb over time, another shot of vaccine acts as a helpful reminder to your immune system to stay vigilant.
The country also has millions of vaccine doses sitting in storage as demand wanes for first and second doses — shots that are difficult to then send overseas.
Some provinces, Ontario among them, have already made the shots available to the elderly or immunocompromised.
That means roughly 250,000 people were already eligible for a third dose, as the province had begun offering it to people considered high-risk, including residents of high-risk congregate settings like long-termcare homes, or people undergoing treatment for tumours or advanced HIV, or other conditions that suppress immune response.
Almost 150,000 Ontarians have already rolled up their sleeves for a third time.
In a tweet Friday, Ontario Health Minister Christine Elliot said the province intended to release a plan next week “that will provide information to all Ontarians on when they can expect to receive a third dose.” The province did not respond to questions about details.
Other provinces, meanwhile, have allowed those with mixed shots to get a third to fulfil requirements for travel. But British Columbia has joined some countries, including Australia, in opening the floodgates and offering another shot to anyone over 18 whose second shot was at least six months in the past.
In some ways, the debates over who should get another shot and when evoke a sense of déjà vu, as health professions revive conversations about who should be prioritized when vaccines started rolling out.
But heading into a second pandemic winter, the goalposts have moved.
“It’s a very different algorithm now,” said Dr. Zain Chagla, an infectious diseases physician and associate professor at McMaster University in Hamilton.
Last year, prioritization decisions were made based on who was at risk of complications or being exposed to the virus. While that general principle still holds, Chagla noted that the vaccinated people at greatest risk of breakthrough infections tend to be those who are older or immunocompromised, whose bodies may not have responded as well to the first two shots.
“But when you start talking about people like community workers, those with two doses in their system, who are relatively healthy and young, their risk of serious complications goes down significantly,” he said.
“This is a little bit murkier.” The concern about waning immunity is that, over time, the antibodies in your nasal passage start to drop off, Chagla said. However, the ones in your bloodstream and elsewhere largely remain.
In other words, your body’s first line of defence becomes weaker, though the bulk of your immune system’s army remains able to fight off serious infection.
The NACI recommendations note that, in addition, the current crop of COVID vaccines “may be less effective” against the highly transible Delta variant.
“Therefore, an additional or booster dose may be needed to obtain more durable protection in some populations.”
What that means is there is some evidence that some countries are starting to see more breakthrough infections — meaning COVID vaccines in fully vaccinated people, particularly seniors — though people still remain mostly protected against serious illness, Chagla said.
He stressed that the vaccines are still very good at protecting against serious disease, even if the time may have come to talk about a bit of a top-up for people who are particularly vulnerable.
According to NACI, data from Israel suggests that a third shot of an mRNA vaccine given six months after the last provides a “robust immune response” against both regular COVID and the variants; occasionally resulting in even more antibodies than after the initial vaccination.
Safety-wise, a third shot seems to be similar to a second, the report adds.
Still, as the possibility of expanding third doses becomes increasingly likely, global health advocates have pointed out another factor that has only become more urgent this time around — the fact that people in many countries are still waiting for even their first dose.
Speaking at a meeting of aid groups Thursday, the World Health Organization’s chief scientist, Soumya Swaminathan, said vaccination rates remain low, and that will be difficult to change if rich countries start buying up booster doses.
NACI’s new recommendation “acknowledges the importance of global equity” but points out that global vaccine supply is outside its purview.
The issue of wealthy countries snapping up a disproportionate chunk of the global vaccine supply is also a replay of earlier this year, experts say.
Despite several weeks of furor last spring, from Canadians worried that the country wasn’t first in line for vaccines, the federal government has actually locked in deals for more doses per capita than almost anywhere in the world.
According to an online tracker maintained by the Duke Global Health Innovation Center, Canada has prepurchased 11.47 doses of vaccine for every person in the country — enough to fully dose everyone roughly six times.
That’s more than any other country, and now, Canada is one of the most heavily vaccinated countries in the world.
That said, some of Canada’s deals are for doses that haven’t been authorized yet, like the shots developed by Novavax or Medicago. There are also millions of doses sitting in storage around the country, and doses that have already arrived in another country aren’t preferred by global donation programs.