Canada ‘long way from herd immunity,’ says expert, predicting figure at 60 to 65 per cent

As COVID-19 vaccination efforts continue, some public health restrictions could be peeled back once up to 65 per cent of Canadians receive a jab—a figure somewhat in line with another Commonwealth nation, says one expert advising the federal government. Dr. Timothy Evans, the executive director of the feds’ COVID-19 Immunity Task Force, told the House Health Committee Monday that as more doses come online, health officials can better understand what level will create herd immunity in the population. But, he said, Canada is still a “long way” off. “We may see an opportunity to dial back when we get to 50 to 60 per cent of Canadians vaccinated. However, before that time, we really have to continue to promote adherence to , which we know make a difference,” he said. Herd immunity refers to the number, or percentage, in a population that needs to be hit to act as a “protective layer” to those within the group who have yet to contract the virus. It can be achieved through vaccinations or resistance built from those who have already had the disease. Bloc Québécois MP Luc Thériault, pictured in 2016, sits on the House Health Committee. The Hill Times photograph by Andrew Meade Bloc Québécois MP Luc Thériault (Montcalm, Ont.) asked if the calculation requires full vaccination with two shots or whether a single dose regimen will do. In response, Dr. Evans said it’s instructive to watch the United Kingdom, where more than half of the population has one dose and infections are falling. According to the BBC, more than 34 million people in the U.K. have gotten their first jab, with more than 14 million people getting their second. “Given what we can see in the United Kingdom, they have reached about 52 per cent of the population, and we see the infection rate continues to decrease with only one dose,” said Dr. Evans. “So I think that it's possible to see something similar in Canada.” But, he noted, given the fewer cases in Canada, the country’s immunity derived from infections will likely be “much lower, so maybe we’ll need to wait until we reach 60 or 65 per cent. But we’ll see.” According to the Public Health Agency of Canada, there have been 1.2 million cases of COVID-19 in Canada since the start of the pandemic, a figure that sits at more than 4.4 million in the U.K. https://twitter.com/PHE_uk/status/1389237961749934088 According to COVID-19 vaccination tracker, more than 33 per cent of Canadians had gotten their first dose of the vaccine, as of Monday. That amounts to 12.8 million people. Among those who have or had COVID-19, about 1.3 per cent have gotten their first doses, per Global News. Dr. Evans’ remarks come less than two months after another official hinted in February that the figure could climb up to 90 per cent in the face of emerging variants. Dr. Supriya Sharma, chief medical adviser with Health Canada, said at the time the figure is a “moving target” but noted that in the earlier days of the pandemic, estimates sat at about 60 to 70 per cent. She said “a lot of people '' had tweaked that to 90 per cent to respond to more contagious variants, so Dr. Evans’ latest figures appeared to signal a tamer estimate than most recently thought. (Typically, the target sits anywhere between 50 and 90 per cent for a virus.) https://twitter.com/PattyHajdu/status/1385615841446801408 Health and government officials have said herd immunity is important to guide when restrictions can be lifted. Individual immunization is also likely to lead to lighter restrictions. Health Minister Patty Hajdu (Thunder Bay-Superior North, Ont.) recently said the feds will soon offer advice on what an immunized person can and cannot safely do, which has already been laid out by some countries. According to CTV, fully vaccinated Americans have been given the greenlight to resume their domestic travel plans without having to take a COVID-19 test, and they do not need to self-isolate after getting back from an international destination. Last week, the U.S. Centers for Disease Control and Prevention added that those fully vaccinated do not need to wear a mask outdoors unless they are in a large crowd of people. Conservative MP Michelle Rempel Garner, pictured in December 2020, is one of several Hillites who have been wondering what 'benchmarks' will be considered in peeling back public health restrictions. The Hill Times photograph by Andrew Meade Several MPs have tried to ask witnesses before the committee about what “benchmarks” to guide such decisions in Canada could be. That question was echoed by Conservative MP Michelle Rempel Garner (Calgary Nose Hill, Alta.), who is also the party’s health critic, on Monday. Dr. Evans said there are “a number” of ongoing studies looking at how long protection lasts after an infection or vaccination, but given researchers are still looking to “enrol” participants, the timing for results remains unclear. “I think the important issue is the extent to which you can generate valid findings over time. When duration is one of the variables, it’s hard to accelerate or diminish that time interval,” he said. Supply and the rollout of vaccines will also play a role in determining any timelines. Preliminary data the task force has received so far shows that immunity after an infection “remains strong and protective for at least eight months,” he added. That could vary for older Canadians who live in long-term care settings, as they may have “a less robust immune response. “As we follow cohorts of infected persons and, now, vaccinated persons, we’re going to gain more insights on just how long immunity from infection and vaccination lasts in different age and sex groups, and when booster doses may be needed,” he said. Vaccines ‘only route’ to herd immunity, says executive director The task force was struck in April 2020, has a two-year mandate and works virtually. It is co-chaired by Dr. David Naylor, who helped pen a 2003 report that drew on lessons from SARS and identified gaps in preparation for future outbreaks. Shortly after Canada’s immunization campaign kicked off in mid-December, the task force was asked in January to “take a major role in supporting vaccine surveillance” with an eye on tracking effectiveness and safety, said Dr. Evans. Since being established, it’s “supported” some 80 studies, which kicked off in May 2020 and are “ongoing” amid a third wave. According to some of this data, in June 2020, the level of immunity in Canada was “extremely low” at less than one per cent, a figure that rose to 1.5 per cent, according to updated results shared in January. https://twitter.com/davidakin/status/1389254608472707076 “The abundantly clear messages that are emerging from our serial prevalence data are that one, we’re a long way from herd immunity, and two, vaccines are the only route to herd immunity,” said Dr. Evans. He added that governments should target their vaccine rollout to “materially deprived neighbourhoods and racialized communities,” given the increased risk they face of being infected. According to data received by the task force, the risk of infection for those living in these neighbourhoods is five times greater than the least materially deprived neighbourhoods. That rate is growing almost three times as fast, he said, adding that for racialized communities, the risk of infection is three times greater than the white population and this rate is growing at about twice the speed. Studies relied on the Material Deprivation Index, which is based on postal codes and was created in the late-1990s to log socioeconomic characteristics of a population living in a small region. The Hill Times

Canada ‘long way from herd immunity,’ says expert, predicting figure at 60 to 65 per cent

The estimation comes less than two months after one official predicted the country’s herd immunity goal could rise to 90 per cent in the face of more contagious variants.

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