News that Canada will begin welcoming fully vaccinated US travellers on Aug. 9, and international visitors on Sept. 7, comes as COVID-19 cases are surging south of the border and in many countries around the world, but infectious disease experts maintain the risk posed by visitors – if they’re vaccinated – is low.
Dr. Sumon Chakrabarti, an infectious disease specialist in Mississauga, Ont., says opening the border to vaccinated travellers is the next logical step in re-opening plans, and marks a shift from efforts to eliminate risk to those that mitigate it.
“The risk won’t be zero… (but) we have to start making these adjustments to move back to normal,” he says. “We can’t stay in suspended animation with our nearest neighbour.”
COVID-19 cases in the US have tripled to more than 35,000 a day compared to a month ago, but still considerably less than the 250,000 cases in January before its vaccine rollout sped up. But while over 55% of Americans are at least partially vaccinated and 48% fully vaccinated, the vaccination rate has slowed to a trickle.
However, in Canada the one-dose vaccine rate is 70% of the total population and over 50% are fully jabbed (the numbers are approximately 80/60% when excluding children under 12 who are not eligible to be vaccinated), with the double-dose rate increasing about a percent per day.
Chakrabarti says a fully vaccinated person can still catch COVID-19, though it happens rarely, and illness is less severe when it does occur. While vaccinated individuals can still spread the virus, that risk is also “significantly reduced,” he adds.
A recent study from the United Kingdom compared spread among household contacts after vaccinated and unvaccinated family members got COVID-19. The study found at least one dose cut transmission to unvaccinated members by 40 to 50%.
Another pre-print study from Israel, which has yet to be peer-reviewed, suggests vaccines are 88.5% effective against transmission.
“So, it’s clearly not 100%, but (vaccination) really does eliminate the transmission chain,” Chakrabarti said.
Nazeem Muhajarine, an epidemiology professor at the University of Saskatchewan, notes, however, that while spread from a fully vaccinated traveller would be rare, unvaccinated, or partially vaccinated Canadians are vulnerable, especially if visitors unknowingly bring in new variants of the virus.
Muhajarine, who’s also one of the leads for CoVaRR-Net, Canada’s research network on variants of concern, says a traveller’s country of origin should still be considered regardless of their vaccination status. Visitors from Peru, for example, where the new Lambda variant is entrenched, could pose more risk.
“The fact that they are fully vaccinated, that’s an important piece of information,” Muhajarine says. “But we also need to pay attention to the epidemiological scenario of where they’re coming from.”
When visitors begin arriving, they will be required to show proof of vaccination and a negative PCR test taken before entry – the same protocols required of returning Canadians that were introduced on July 5.
Dr. Ilan Schwartz, an infectious disease researcher with the University of Alberta, expects the latter negative-test provision to remain in play as a way to drive risk from “extremely low to even lower.”
And he adds, “We’re already starting from a place where, in the absence of symptoms or the absence of exposure to a known case, the likelihood of travellers importing the virus into Canada is low.”
Schwartz says Canada will also have to determine which vaccines it will accept in its definition of a “fully vaccinated” visitor.
Parts of the world, including Russia and China, use vaccines that aren’t authorized by the World Health Organization and have “little or dubious public data,” he says, but adds, being “overly elitist” in qualifying vaccines could pose ethical issues.
Muhajarine says as more countries begin excluding unvaccinated travellers from entering their borders, that could incentivize more people to get their jabs, elevating vaccine uptake in Canada and elsewhere.
But while Chakrabarti says limiting travel to fully vaccinated people makes sense, any missing details in the rules could spur confusion, especially among families hoping to travel with unvaccinated children.
“What happens if you have five members of a family who are vaccinated and one who isn’t?” Chakrabarti says. “There’s a lot of unknowns here and a lot of unintended consequences that this could lead to.”
Leger survey
As for the general public, a new poll by Leger suggests a majority of Canadians believe proof of vaccination should be required of all essential and non-essential travellers.
The July 16-18 survey of 1,529 adult Canadians found that 66% of respondents say people should be fully vaccinated to be allowed to cross the border, while 16% say providing a recent negative test is enough and 14% say border crossing should be limited only to essential travel.
And 58% of respondents feel travellers should be required to show a document that proves they are immunized against the novel coronavirus, while some 30% believe a so-called vaccine passport is not necessary.
The poll also suggests that a minority of 48% of Canadians support the total reopening of the Canada-US border at the end of August, including to tourists, while 52% say they oppose the reopening.