do covid-19 boosters still make sense? what to know about the latest vaccine rollout
covid is still circulating but canadians' intentions to get a booster dose of a covid-19 vaccine have decreased dramatically since 2021
5 minute read
a health worker administers a dose of a covid-19 vaccine during a vaccination clinic.
file photo
rodney russell, who was “one of the biggest covid vaccine cheerleaders out there,” admits to now feeling complacent himself about covid. “i believe the vaccines did their job,” said russell, a professor of virology and immunology at memorial university of newfoundland. “the shots got us through the pandemic. they helped us get back to normal. they provided immunity, especially when we hadn’t had natural infection frequently.” for most people, “the vaccines were the first bit of immunity we got.”
still, russell understands why enthusiasm for updated boosters has waned. “people don’t think they need them anymore,” he said.
but while there may not be the same urgency, the risk of long covid increases with each new infection, the elderly and immunocompromised remain vulnerable to severe covid disease, emergency rooms are overloaded and the country is grappling with a family doctor crisis. there is “no doubt,” russell said, that there is a benefit to getting the vaccine.
“the public health answer is always going to be that, even if we have a short duration of protection (against infection) from the vaccines, those short periods when somebody can’t get infected and spread covid is still, in the big picture, contributing to less virus in the community,” russell said.
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at an individual level, people need to ask, “who is in my circle, and who might i make sick?”
ontario and other provinces have begun opening up free updated covid-19 booster doses to everyone aged six months and older. canada’s panel of vaccine advisers has strongly recommended the new vaccines targeting the kp.2 strain, part of the omicron lineage, for the previously vaccinated or unvaccinated at increased risk of severe covid disease.
all others who aren’t at increased risk “may” receive the most recently updated shots, the national advisory committee on immunization recommended back in may, in advance of an anticipated fall campaign, the word “may” reflecting what the panel describes as a discretionary, rather than strong, recommendation.
national post spoke with russell and mcgill university genomic evolutionary biologist jesse shapiro about the updated covid vaccines, who they’re recommended for and where we’re at with covid.
how are the new vaccines different from last fall’s boosters?
the updated mrna vaccines from moderna and pfizer-biontech target the kp.2 strain, part of the omicron lineage that began spreading last spring and drove a summer wave.
the strains currently circulating are mostly descendants of kp.2, meaning the vaccines should be “a pretty good match,” shapiro said. with a rapidly evolving virus, it’s never going to be a perfect match, but even an imperfect match “provides a good boost and diversifies your immune response.”
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who should get a booster, and when?
according to naci, all adults 65 and older, those with underlying medical conditions (including kids with complex health needs), pregnant women, residents of long-term care or other congregate living settings, individuals in or from first nations, métis and inuit communities and members of racialized communities.
it’s recommended people wait a minimum of three months from the last covid shot or infection, and up to six months before getting vaccinated again. the vaccines can be given the same day as other non-covid vaccines, like flu shots.
how long does immunity against infection last?
“you’re probably going to get three months of protection against infection,” russell said. but protection against severe disease, hospitalizations and deaths typically last longer than protection against infection.
why we see such relatively rapid waning immunity with sars-cov-2 isn’t clear. “i’ve seen reports of multiple infections with the same coronavirus within the same year,” russell said. the immune response following vaccination or infection appears relatively weak compared to other vaccines and other infections.
age is a factor. immune systems tend to weaken with age. those opting to get boosted tend to be older, “so you’re giving the vaccines now to people who aren’t going to make as good a response as younger generations, meaning you’re starting at a lower level of immunity,” russell said.
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is the immune response more vigorous following infection versus vaccination?
with vaccination, people make a response against one protein, the spike protein that studs sars-cov-2’s surface. “with natural infection, you’re making an immune response against all parts of the virus. it’s a broader response,” russell said. using a hockey analogy, it’s like “putting the whole team in versus just the goalie.”
“if you’ve been infected a month ago, i’d say your booster isn’t going to do much for you. but if you were infected six months before, chances are your antibodies are low enough you can get infected again.”
why is booster uptake falling?
nationally, canada has one of the highest vaccination rates in the world (85 per cent of the total population has received at least one dose). but while pharmacists in british columbia recently reported record-breaking days doling out covid vaccines and flu shots, overall, “intentions to get a booster dose have decreased in canada” since booster shots were first recommended in 2021, according to an evidence brief published in a recent issue of the canada communicable disease report.
reasons for being unlikely to accept a booster included concerns about side effects, concerns about the safety of receiving multiple or mixed brand doses, vaccine fatigue and our human desire “to move past the events of the pandemic,” the authors wrote.
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there’s also less messaging around covid and recommended boosters from public-health officials.
how is sars-cov-2 behaving?
nationally, indicators of sars-cov-2 activity, like the percentage of tests that were positive, were stable for the weekend ending oct. 26. but another covid surge, based on previous years, is expected during the fall and winter months.
russell had thought the virus would have settled into a predictable seasonal pattern by now. it hasn’t, possibly because we haven’t built up decades of immunity against sars-cov-2 the way we have with other viruses.
sars-cov-2 is also changing, a lot, mutating to dodge immunity from previous infections and vaccinations, which shapiro described as “a kind of arms race between people’s immune systems and the virus.”
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