Canada can avoid the worst of the fourth wave-but we are not out of the predicament yet

Canada can avoid the worst of the fourth wave-but we are not out of the predicament yet


This is an excerpt from Second Opinion, a weekly review of health and medical science news, sent to Subscribers every Saturday morning.If you haven’t subscribed yet, you can click here.

As the highly contagious delta variant continues to spread before borders and schools are reopened, Canada may face a fourth wave of pandemics, but there is growing optimism that another wave of surges will not bring the country back to crisis point .

Canadian immunologists, virologists and infectious disease experts said that due to the effectiveness of the COVID-19 vaccine and the willingness of Canadians to vaccinate, we may perform better than previous waves and have a lower rate of serious infections.

but Our launch is at a standstill And there is still a large number of people who have not been vaccinated—whether voluntarily or because of inability to obtain or lack qualifications—including millions of Canadian children who have only returned to school in just over a month.

Matthew Miller, associate professor of infectious diseases and immunology at Hamilton McMaster University, said: “We will see an increase in the number of cases again at some point.”

“It may be similar to last year, when we enter autumn and the cold weather arrives. But hopefully these bumps are just like this-small hills, not peaks like the previous waves.”

After the city of Montreal lifted public health restrictions, people took a walk in the city center on June 3. (Jean-Claude Taliana/CBC/Radio Canada)

How bad will Canada’s fourth wave be?

The severity of the fourth wave of the Canadian epidemic will largely depend on the population’s level of immunity to vaccines or previous COVID-19 infections, which can prevent an increase in community transmission and prevent serious cases in hospitals.

Canada has surpassed 1.4 million cases of COVID-19 So far, only 2.6% of Canadians Because they had been infected with the coronavirus before the beginning of 2021, they were found to have antibodies.

“The question is-is there enough population immunity? No,” said Raywat Deonandan, a global health epidemiologist and associate professor at the University of Ottawa.

“This is because we measure population immunity through recovery cases and vaccination.”

Among eligible Canadians 12 years and older, more than 80% have received at least one injection, and more than 60% have received two injections. But when you consider the entire population of the country, this number drops to about 70% with one dose of vaccine, while the proportion of fully vaccinated is slightly higher than 50%.

Although Canada’s immunity is “not enough,” Denandan said, we can “artificially create” enough protection through interventions such as wearing masks indoors to help surround unvaccinated Canadians.” Build a fence” As COVID-19 becomes more seasonal.

He said: “We are seeing the arrival of the epidemic phase of this disease all over the world.” “Because it’s mainly because they don’t have enough people vaccinated-this is the bottom line.”

On May 16, 27-year-old Maria Rey received the first dose of Pfizer-BioNTech COVID-19 vaccine at an overnight clinic at the Mississauga International Center in Ontario. (Evan Mitsui/CBC)

Delta Air Lines threatens to drive COVID-19 surge

Another key factor in Canada’s ability to withstand the severe fourth wave is More contagious, Potential More deadly The delta variant, which is pushing the COVID-19 level in countries around the world to rise.

“For example, we know from observations in the UK that delta is very, very capable of infecting unvaccinated people very quickly,” said Dr. Dominic Mertz, an infectious disease doctor and associate professor of medicine at McMaster University.

“Anyone in the population who has not been vaccinated puts himself at very, very high risk.”

The level of COVID-19 in the UK has risen in recent weeks, Put pressure on the healthcare system. Israel has Restoration of mask regulations To deal with the new epidemic.And the U.S. has seen Inadequately vaccinated states surge Driven by delta.

A new study in the New England Journal of Medicine (NEJM) It was discovered this week that two doses of Pfizer-BioNTech vaccine are 88% effective against delta variants, while the two-dose AstraZeneca-Oxford vaccine is 67% effective.

But there are conflicting reports about the effectiveness of vaccines on delta in the real world, including New data from the Israeli Ministry of Health This shows that Pfizer injections are 39% effective against infections-but they are much better at preventing serious diseases.

Watch | Why the delta variant is different from other variants:

The respiratory doctor broke down the known information about the delta variant of the coronavirus, including how it differs, how dangerous it is, and whether the vaccine can prevent it. 4:26

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, told CBC Power and politics On Friday, a “significant proportion” of the U.S. population remained unvaccinated and faced the highest risk in the Delta.

“This is definitely something we need to correct, because when you deal with mutations like delta mutations, it spreads very effectively from person to person, and you will see a surge in cases,” he said.

“For those who are vulnerable, such as the elderly and those with underlying diseases, their chances of being hospitalized have increased.”

In May 2020, a nurse cared for a patient suspected of having COVID-19 in the intensive care unit of Toronto North York General Hospital. (Evan Mitsui/CBC)

Reopening the border puts unvaccinated schools at risk

Canada may also face greater delta risk because Reopen the border U.S. travelers in the next month and international travelers in September, as well as school return to school, may put unvaccinated Canadians at a higher risk of exposure to COVID-19.

Dr. Allison McGeer, a medical microbiologist and infectious disease expert at Mount Sinai Hospital in Toronto, said: “It definitely will. In addition, the more we travel within the country will increase the risk of mutation.”

“We shouldn’t be surprised if delta variants start to increase dramatically, and we shouldn’t be surprised if we have to go back to some degree of travel and other restrictions.”

The largest group of unvaccinated Canadians are children under the age of 12, and despite ongoing clinical trials, they are not yet eligible for the COVID-19 vaccine. Experts say that the reopening of schools in September may put them at higher risk.

“It is important that we start reporting the percentage of our vaccinations, including children, because this is our actual number,” said Alyson Kelvin, an assistant professor at Dalhousie University and a virologist at the Canadian Center for Vaccinology and Vaccines and Infectious Diseases.

“Considering that we want the herd immunity rate to be higher than 85%, we can’t achieve it without children.”

On August 5, 2020, elementary school students in Godley, Texas, wear masks to prevent the spread of COVID-19. (LM Otero/Associated Press)

Kelvin said that until children under the age of 12 are eligible to be vaccinated in Canada, those with a weaker immune response to the COVID-19 vaccine-including older Canadians and people with weakened immune systems-will continue to be vulnerable.

She said: “Children cannot be vaccinated, and variants such as delta are more infectious-and there seems to be case reports that when children are indeed infected, the severity of the disease will increase.” “This is what we need in the future. Things to pay attention to.”

Future variants pose an unknown threat

An unknown threat facing Canada is that as COVID-19 continues to ravage under-vaccinated countries around the world, there may be more transmissible mutations in the coming weeks and months, which may be more serious than delta.

Before our vaccination campaign started, Canada was hit hard by the alpha variant, and new and more dangerous variants appeared repeatedly in countries that continued to be hit hard with each wave of the past.

“We will definitely see other variants. If they are more serious, or a worrying variant, it is another problem,” Kelvin said. “But it’s an interesting trend… the spread seems to have increased over time, and we are seeing new variants.”

Kelvin said that this usually does not occur in other epidemic viruses such as influenza, which means that the unpredictability of this virus makes it an open issue in the future.

Miller said that COVID-19 may be epidemic in Canada and around the world. Like the flu, it will come back every year. Our ability to control it depends on our ability to get more people vaccinated.

“It will probably continue to evolve for decades. It will not go anywhere. But we have a surprisingly successful vaccine,” he said. “The truth is that there is light at the end of the tunnel. This will end when everything ends.

“But if you are not vaccinated, you are sure-at some point-you will be infected.”

This is an excerpt from Second Opinion, a weekly review of health and medical science news, sent to Subscribers every Saturday morning.If you haven’t subscribed yet, you can click here.

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