Ontario is prioritizing second-dose hotspots as evidence shows the Delta variant is more transmissible and less susceptible to vaccines

Ontario is expanding the eligibility for accelerated second doses in hotspots of the Delta variant.

The variant also known as B. is believed to be behind the devastating second wave in India along with a recent surge in cases in the UK. The province fears that this could now be a catalyst for a fourth wave that begins in the greater Toronto and Hamilton area.

As of June 14, people living in Halton, Peel, Porcupine, Toronto, Waterloo, Wellington-Dufferin-Guelph, and York public health facilities who received their first dose of an mRNA vaccine on or before May 9, can: Make an appointment for a second dose.

“The adoption of vaccines in Ontario continues to accelerate, with over a million doses being administered each week to ensure that Ontario can safely and gradually lift public health measures,” said Minister of Health Christine Elliott.

The alpha variant – originally identified in the UK – is the dominant strain in the province and responsible for much of the third wave, is 40 percent more transmissible than the original strain of COVID-19, says Dr. Gerald Evans, an infectious disease specialist at Kingston Health Sciences Center and Queen’s University in Kingston, Ontario. He says Delta seems 30 to 40 percent more transferable than Alpha.

The severity of the infection caused by the strain is also uncertain. Some evidence, Evans says, suggests that this could lead to a more severe infection, but the evidence is inconclusive.

According to Dr. Raywat Deonandan, an epidemiologist and associate professor in the Department of Health Sciences at the University of Ottawa, could be 2.7 times more likely to be hospitalized if infected with the Delta strain.

However, Deonandan also warns that these numbers are not solid, but rather are being monitored at the population level in India, where the mutation was first identified and where there is less hospital capacity, fewer vaccinations, and high rates of metabolic problems and diabetes.

There are also concerns as vaccines appear to offer slightly less protection than the Delta variant: One dose offers between 30 and 40 percent protection against disease, Evans says.

One dose of Pfizer – the most commonly given vaccine to Canadians to date – offers about 30 to 33 percent protection against Delta, Deonandan says. He adds that two doses give 80 to 90 percent protection and two doses of the AstraZeneca vaccine give about 60 percent protection.

To date, 68.30 percent of Canadians over 18 have received their first dose; but only 7.02 percent are fully vaccinated. This is a particular problem in areas like the Peel region, where the percentage of people who received their second dose lags the provincial average and where the Delta variant cases are high.

Dr. Seema Marwaha, a doctor and co-founder of the South Asian Health Network and associate professor of medicine at the University of Toronto, says hot-spot areas must be prioritized for the second dose of the vaccine to prevent a fourth wave. “And then places that are known as distribution areas within hotspots – and especially workplaces and multigenerational houses in Peel – should have priority.”

An effective strategy to suppress the spread of Delta would be to make sure more vaccines are delivered to Peel to distribute to those at risk, Marwaha says. “It’s important for the province that we prioritize hot-spot regions like Peel, but within Peel it’s also important that we target the groups with the highest risk.”

“Together, these prioritization strategies can help curb the spread of the delta variant and hopefully prevent a fourth wave from spreading across the province.”

On Monday, the Ontario government announced that it would reopen the province earlier than expected on Friday.

It makes sense to reopen at this point, says Dr. Dominik Mertz, Associate Professor of Infectious Diseases at McMaster University in Hamilton. Although Delta is estimated to lag behind a quarter of all positive results in the province, “our case numbers are low enough and the health system has not yet fully recovered, but it is in much better shape than it was a few weeks ago,” says Mertz.

Mertz points to Great Britain, where an increase in the number of cases is readily tolerated by the health system. Mertz says he doesn’t expect a large increase in the number of cases as a result of the reopening of the province.

“We taught people a vaccine, so now it’s a matter of double-vaccinating in the hotspots, and if we do, we should get to Delta without too many problems and without a big resurgence.”

Dr. Gerald Evans, an infectious disease specialist at Kingston Health Sciences Center and Queen’s University

“When Delta creates a problem, it is mitigated by the fact that we have fewer cases,” says Evans. Although the percentage of cases with delta is high, the total number of cases is low, he adds.

“We taught people a vaccine, so now it’s a matter of double-vaccinating in the hotspots, and if we do, we should get to Delta without too many problems and without a big resurgence.”

Currently, says Evans, the variant is mainly limited to the northwest of the GTA and in Kitchener-Waterloo.

However, says Evans, the delta variant does not have either of the two mutations that are used for rapid tests. So to know if an infection is caused by Delta, whole genome sequencing is used. The entire genome of the variant is examined for mutations that indicate which variant it is, and it takes a week instead of just a few hours.

However, Evans is confident that rapid tests for the Delta variant will be available in the coming weeks.

“The goal here has to be to avoid this fourth wave,” says Deonandan. He believes a fourth wave is avoidable, especially with a focus on inoculating hot spots.

“We get enough vaccines for that,” he says. He adds that the schedule for the second dose should also be sped up to at least three months.

But the reopening shouldn’t be rushed, Deonandan says, the first phase is where most activities are low-risk, such as eating outdoors.

The province should maintain this course through August, when at least half of Canadians are expected to receive two doses, he says.

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