A man goes through a sign for a COVID-19 test center in Montreal on October 10, 2021. COVID-19 cases and wastewater levels are rising again in various parts of the country , which raises concerns that another wave has already begun. Graham Hughes / The Canadian Press
There are many unknowns about how a new wave of COVID-19 will occur in Canada in the coming weeks, but doctors and scientists say many of the lessons learned from previous ones can help mitigate its impact.
While the virus continues to change, some of the basic public health tips still apply, said Jeff Kwong, a professor of family medicine and public health at the University of Toronto.
“Ventilation, masks and vaccines still work to varying degrees and for a variety of things,” Dr. Kwong said.
In various parts of the country, cases of COVID-19 and wastewater levels are rising again, raising concerns that another wave has already begun.
Data from the Ontario COVID-19 Scientific Advisory Board show that several indicators in this province, such as test positivity, wastewater levels, and hospitalizations, suggest the virus is on the rise. The number of cases in Quebec is increasing. And according to federal wastewater monitoring data, last updated on July 5, six of the 22 sites registered nationwide showed a possible increase in COVID-19 levels in wastewater, compared to seven days earlier. These include places in Halifax, Charlottetown and Vancouver.
“It’s a question of how serious and serious it is, but it’s definitely a wave,” said Tania Watts, an immunologist at the University of Toronto.
One factor that will shape how this wave will be is the amount of immune protection the public has against the virus.
A new analysis of blood test data by Canada’s COVID-19 immunity working group, released Wednesday, suggested that the proportion of Canadians who had antibodies to SARS-CoV-2 infection, the virus that causes COVID-19, increased by 45 percent. This suggests that more than 17 million Canadians were infected by the Omicron variant. Prior to the introduction of Omicron, about 7% of the population had antibodies acquired from SARS-CoV-2 infection, the working group said.
Meanwhile, about 82% of the total population is considered fully vaccinated against COVID-19, and nearly 60% of those over 12 have received at least one additional dose, according to federal data.
However, BA.5, the new variant about to become dominant in Canada, is able to evade immune protection. That means everyone who caught Omicron is now susceptible to reinfection again, Dr. Watts said.
Research led by University of Toronto scientist Igor Stagljar supports this. Using a new antibody test he and his team developed, they found that the immune protection acquired from a previous vaccine or infection only lasted four months against the new variants, BA.4 and BA.5.
“If someone had COVID earlier this year or if someone got vaccinated earlier this year, that means we have zero, almost zero, protection in the form of neutralizing antibodies,” Dr. Stagljar, professor at the Donnelly Center for Cellular and Biomolecular Research at Temerty School of Medicine.
In addition, some of the drugs used for COVID-19 have no longer become effective with the advent of new variants, said James Heilman, an emergency physician in Cranbrook, BC. For example, a few months ago, I was using sotrovimab, an injectable antibody. to treat patients with severe COVID-19, but with the advent of Omicron, treatment no longer works.
It is also becoming clear that Paxlovid, which was previously thought to be a possible panacea, is only useful for those at high risk for serious illness, said Drs. Heilman.
Despite these new challenges, however, the main way to contract COVID-19 has not changed.
“The disease has been transmitted through the air from the beginning,” said Dr. Heilman, editor of Wikipedia’s medical content.
This means that high-quality masks still work to reduce the risk of infection, not just from COVID-19 but from other respiratory viruses, Dr. Kwong said. Cloth masks are better than nothing, he said, but he stressed that N95 or KF94 respirators are best.
Dr. Watts said the now-known writing still applies that meeting outdoors is safer than indoors. The same goes for the idea that small groups are safer than large crowds; The chances of getting COVID-19 in a room with 1,000 people are still higher than in a room of 10 people, he said.
And while contact with infected surfaces may not be the main route of transmission, washing your hands is still a good idea, Dr. Watts said.
But now some health messages need to be modified or removed, they said.
Keeping two meters away from others will not necessarily keep people safe, Dr. Kwong said. If they spend time in an enclosed space where many people are generating many small particles, transmission can occur, even when they are all separated, he said.
Current guidelines, which call for isolation at least five days after the onset of symptoms or a positive test and masking when in public from days six to 10, could also use the review, Dr. Watts said. In some cases, the virus can be removed after the fifth day, so it is recommended to do a quick antigen test after five days and stay home longer if the test is positive.
Dr. Heilman added that people should not assume that they are free of COVID-19 just because they test negative on a quick test. There may be several days of symptoms before people get a positive test, he said.
Also, having a two-dose vaccine should no longer be considered fully vaccinated, but should be considered a three-dose vaccine, Dr. Watts said. While vaccines do not completely protect people from infection, they do provide good protection against serious illness and reduce the risk of long-term COVID, he said.
However, given the speed with which immunity decreases, Dr. Stagljar suggested that Canadians may expect to need an additional dose every four to five months. A test that measures neutralizing antibodies, like the one he and his team have developed, could help determine when people need a booster dose, he said.
Ultimately, it is a mistake to think that efforts to stop the spread of COVID-19 can be abandoned just because it is not killing or seriously injuring so many people, Dr. Watts said, adding that infections allow the mute virus even more.
“We all have a contribution from society not to spread COVID and make the general pandemic worse, and also obviously affect the vulnerable,” he said.