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COVID modelling shows substantial progress, key to fighting Delta variant is second doses

Last Updated Jun 10, 2021 at 4:58 pm EDT

Ontario released new COVID-19 projections on the eve of its economic reopening, demonstrating improvements in several areas as health officials point to second-dose vaccinations as a solution in controlling and limiting the spread of the Delta variant.

The modelling, presented by Dr. Adalsteinn Brown, shows cases, percent positivity, and hospitalizations have all dropped sharply “thanks to the commitment of Ontarians.”

The Science Advisory Table expects daily COVID-19 cases to decline for the next 10 days, adding that as vaccinations continue to ramp up, it will be important to monitor variants for signs of breakthrough and serious infection.

“To help avoid a fourth wave, we need to continue to ensure first and second doses in high-risk communities,” said Dr. Brown on Thursday. “We need to make sure our vaccine efforts are tailored to community needs and we need to ensure the core public health functions and strong contact tracing.”

Echoing what Peel Region’s top doctor said recently, Dr. Brown and his team say the Delta variant is more transmissible and may be more dangerous than other strains and will become the predominant variant in Ontario throughout the summer.

Among the key findings from Thursday’s modelling, the Science Advisory Table says containing the Delta variant is critical.

“… To avoid a fourth wave, we need to continue to ensure second doses in high-risk communities,” Dr. Brown repeated.

COVID-19 modelling key findings – Thursday, June 10


It was announced by the province and by Toronto that vaccine allocation will focus on hotspot communities and postal codes where the Delta variant is most prevalent.

As of Monday, anyone in the province that received a first dose of a vaccine on or before May 9 living in Toronto, Peel Region, York Region and other GTA public health units can book a second dose appointment.

The latest modelling shows that second doses are key in preventing severe infection against the Delta variant, which is more than 50 per cent transmissible than the Alpha B.1.1.7. strain first detected in the UK.

A first dose of a vaccine, which Dr. Lawrence Loh categorized as being roughly 33 to 50 per cent effective against the Delta variant, offers less protection against symptomatic disease but it may shield against severe disease.

“To further stop the spread of COVID-19 and support Delta hot spots, we are further expanding booking eligibility for an accelerated dose in select regions across the province,” Health Minister Christine Elliott said Thursday.

If the spread of infections does keep slowing, Ontario could fall below 200 COVID-19 patients in ICUs by mid-July, allowing normal hospital operations to resume, the modelling data indicates.

In a best-case scenario, modelling shows daily case counts will continue to steadily decline despite Ontario’s reopening and will drop below 300 by mid-August.

One middle scenario shows that with 142,000 vaccinations administered in Ontario per day, daily case counts would come in around 800 to 900 by mid-August.

With slightly more vaccinations (180,000) a day, the province could report 500 new daily infections by mid-August.

Finally, in a worst-case scenario, the spread of more infectious variants would lead to a fourth wave of the pandemic with daily case counts reaching 2,500 by mid-August.

The latest data shows Ontario has now surpassed both the U.S. and UK in relative terms when it comes to the percentage of the population who have received one dose of a COVID vaccine.

The province has now also matched or outpaced Israel in terms of first dose vaccination rates.

Modelling paints positive picture as Ontario enters Step 1 of reopening plan

The last round of projections presented by Ontario’s Science Advisory Table painted an optimistic picture for the province heading into the summer months.

At that time, Dr. Brown said if the province could maintain 130,000 vaccine doses per day and keep public health measures in place with a partial reopening by June 16, the province could see well below 1,000 new daily infections by the end of June.

Ontario has been administering more than 140,000 doses a day in the 20 days since the last numbers were presented and have now reported below 1,000 new daily cases for ten consecutive days.

The rolling seven-day average of new daily infections has dropped to 657, reaching the lowest point since early October. Ontario reported 411 new cases on Wednesday, the smallest daily increase since late September.

The province will move into Step 1 of its economic reopening plan at 12:01 a.m. on Friday.

The move will allow for patio dining at a maximum of four patrons per table and limited non-essential retail shopping to resume at 15 per cent capacity ahead of the upcoming weekend.


Step 1 of the Ford government’s plan was tentatively slated for June 14 but with COVID-19 indicators improving the decision was made to kickstart the plan a few days early.

The reopening plan outlines that Step 1 will remain in place for at least 21 days to assess impacts on key public health and health system indicators.

Before Step 2 can begin, 70 per cent of Ontario adults need at least one dose of a COVID-19 vaccine, and 20 per cent need to have received both doses. Step 2 would allow for hair salons to reopen and indoor gatherings of up to five people.

Approximately 73 per cent of Ontarians over the age of 12 have now received at least one dose, while 10 per cent of residents are now fully vaccinated.

Concerns surrounding Delta variant

Health officials have expressed some concern and are urging caution as the rise in the more transmissible Delta strain coincides with partial reopening around the corner.

The top doctors in Toronto and Peel Region have both warned that if residents let their guards down at the current vaccination rates – a fourth wave could be triggered.

In Peel, the Delta variant is poised to become the dominant strain this month, and experts fear it could spread across the province if it isn’t contained.

“On Friday I want to remind our residents these first steps to reopening are not a full return to normal. We do have high first-dose coverage but we have low second-dose coverage,” said Peel Medical Officer of Health Dr. Loh.

The NDP has called on the Ford government to prioritize sending second doses of vaccines to hot spots where a more infectious virus variant is spreading to help avoid another lockdown.

“People need to have confidence that this early reopening won’t backfire,” said NDP deputy leader Sara Singh. “In order to guarantee that, the Ford government needs to do what the experts are telling them to do: offer everyone in a hot spot a second dose of the COVID vaccine right now.”

Dr. Eileen de Villa said this week there are 122 cases of the variant confirmed in Toronto, but the confirmation process is slow and the picture can change quickly.

“With the Delta variant here, we will want to do two things in particular, increase first and second dose vaccine coverage and proceed selectively in daily life.”

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