Ontario has likely entered new COVID-19 wave driven by BA.5 subvariant, science table warns

Ontario has likely entered a new wave of the pandemic driven by the more infectious BA.5 subvariant, the province’s science advisory table says.

The table made the declaration in a series of messages posted to Twitter on Wednesday afternoon, citing “exponential growth” in case counts in about 80 per cent of public health units as well as rising hospitalization numbers and test positivity rates.

The scientists also said that the wastewater signal in most regions is now rising, pointing to higher levels of viral activity overall.

“Current evidence does not suggest BA.5 is more severe or that it will lead to a rise in hospitalizations as large as previous waves. However, any surge comes at a time when hospitals are already dealing with staff shortages and record wait times – this impacts all of us,” the table said. “And if BA.5 spreads widely, we may see a rise in deaths among higher risk groups such as the elderly as was observed during the previous waves.”

The warning from the science table comes as a number of countries experience a rapid rise in transmission due to the BA.5 subvariant.

In Ontario, where the subvariant is now dominant, most public health indicators are also starting to head in the wrong direction after months of gradual improvement.

The most recent data released by the Ministry of Health on June 30 showed a week-over-week increase in COVID-19 hospitalizations for the first time since May.

The positivity rate on PCR tests was also up, with the seven-day average going from 7.64 on June 23 to 9.82 on June 30.

Meanwhile, the public health measures that existed during previous waves of the pandemic are now all gone, including a mask mandate for high-risk settings that was terminated last month.

Speaking with CP24 on Wednesday afternoon, Ontario’s Chief Medical Officer of Health Dr. Kieran Moore said there are currently no plans to revive mask mandates in light of the rise in transmission but he did urge Ontarians at risk of a more severe outcome from COVID-19 to consider wearing a mask in indoor public settings.

“This is a global phenomenon. All countries in the western hemisphere are experiencing this,” he said of the uptick in cases. “As our borders are opening, as travel returns it is natural that this virus will circulate globally. But Ontario to date is doing very well at minimizing its impact on the health care system.”

The science table did say that the “rise in hospitalizations will likely be smaller than earlier waves,” but at the same time it noted that it will place significant stress on hospitals, given that COVID-19 hospitalizations “remain higher than at any time last summer.

The table is also warning Ontarians that the new subvariant could have some properties which will help it evade immunity, meaning that individuals can be re-infected by BA.5 even if they have “recently been infected with an earlier strain.”

“I would like to just point out that there are 5 million Ontarians who still haven't taken advantage of our first booster dose and one million of them are over 50 and in our opinion at risk for severe outcomes from COVID-19,” Moore told CP24. “So please stay up to date with your vaccinations. I appeal to those 5 million Ontarians that haven't taken advantage of the first booster to please come forward.”

The science table says that Ontarians should take a number of precautions as a result of the rise in transmission, including “going back to wearing a mask again in crowded indoor public spaces” and ventilating indoor spaces as much as possible by opening windows and doors.