Ontario has officially entered its seventh wave of COVID-19, driven this time by the Omicron BA.5 subvariant, the province's top doctor confirms.
"Sadly yes, we're in another wave," Dr. Kieran Moore, the province's chief medical officer, told CBC News Wednesday after Ontario's COVID-19 science advisory table pointed to exponential growth in most public health units.
The BA.5 subvariant has been rising slowly since early June but really started to "take off" mid-month, becoming a dominant strain, Moore said. Approximately 60 per cent of confirmed cases now are a result of the subvariant, Moore said.
Ontario can likely expect another four to five weeks in this wave, which is now in about its third week, he said, adding infections are expected to increase over the next 10 days before beginning to slow.
As for fourth doses, Moore says the focus has been to prioritize boosters for those over 60 years of age and those most vulnerable, while encouraging third doses for the rest of the population.
The province is now reviewing eligibility for fourth doses, however, and will have more to say in the coming weeks, he said.
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The new wave comes amid the summer months when many are spending more time outdoors — something that would have otherwise been expected to help curb the spread of transmission, raising questions about what will happen as more people head indoors later in the year.
"Lots of unknowns for the fall but I can assure all Ontarians we're preparing for it," said Moore.
"We may ask Ontarians to wear masks as we go indoors into the fall and we may mandate it if our health system has too many people getting admitted, too many people waiting in emergency departments... All of us want to maintain our health system capacity."
In a series of tweets Wednesday, the science table pointed to several key indicators signalling the beginning of a wave, little more than a month after the end of most public health measures, including mask mandates.
Test positivity above 10% for 1st time since May
For the first time since May, test positivity is above 10 per cent, with wastewater signals rising across the province overall and within most regions, the science table says.
Around 80 per cent of public health units are seeing exponential growth in cases, though the group says the actual reproduction number is hard to nail down since the province moved to limit PCR testing.
On top of that, Ontario is seeing its first increase in COVID-19 hospitalizations since May, with the number of people admitted for the virus higher than at any time last summer.
The latest numbers tracked by the science table show that as of June 29, 605 people were hospitalized as a result of the virus. That's an increase of 89 people from the week before.
An estimated six people per day died from the virus as of July 3, up from three the week before, the group says.
Indications of a new wave in Ontario come as several G10 countries have already seen a jump in cases driven by Omicron subvariants, including France, the U.K., Italy, Belgium and Switzerland, among others.
Get 3rd doses 'now' if you haven't already, group says
The group says current evidence does not suggest BA.5 is more severe than strains that drove previous waves or that it will lead to the level of hospitalizations seen at earlier points in the pandemic.
"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 advisory 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."
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The group advises anyone in a crowded indoor public setting to wear a high-quality mask and to ventilate as much as possible by opening doors and window for air flow.
Anyone over the age of 18 who hasn't had a third dose of a COVID-19 vaccine should "get it now," the group says.
Anyone age 60 or over or immunocompromised should also take their fourth dose now, it says, noting while updated vaccines targeted to newer variants might be available this fall, "it makes sense to get the vaccines you are eligible for now."
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"You can be re-infected by BA.5 even if you have recently been infected with an earlier strain," the group says. "Non-severe infections can still be disruptive to your life and increase long COVID risk."
Providing a clear, full picture about the state of COVID-19 has become increasingly difficult over the last several months, after the provincial government restricted lab testing and stopped publishing school-related data.
On June 11, the province also switched to weekly reporting of COVID-19 data after more than two years of daily updates.