Race underway to get 2nd vaccine shots done before new variant takes over

Two eastern Ontario science advisers say the province is in a race against time to get enough second doses of COVID-19 vaccine into arms before a variant originally identified in India takes over.

The delta variant, as it was recently re-named by the World Health Organization in an effort to simplify coronavirus variant names, is driving a new wave of COVID-19 cases in the U.K.

"The main thing we want to do now is get vaccinations high enough — and that includes second doses now — to slow this down," said Troy Day, a member of the Ontario Modelling Consensus Table and a mathematician at Queen's University in Kingston, Ont.

Ontario's modelling this week shows the delta variant is set to take over from the alpha variant, previously known as B.1.1.7.

Experts say the delta variant appears to be 50 per cent more transmissible and causes more severe symptoms, leading to calls for even more caution as Ontario sets to reopen in two weeks. 

A recent finding by Public Health England also shows a single shot of Pfizer and AstraZeneca results in only 33 per cent effectiveness against "symptomatic disease" from the delta variant, compared to 50 per cent against alpha.

However, effectiveness improves with a second dose. 

In Ontario, there have already been outbreaks involving the new variant, with delta being reported in Ottawa's wastewater data.

The latest findings from samples in Ottawa wastewater shows the delta variant present since at least late April, though 90 per cent of COVID-19 in wastewater remains the alpha variant. 

There have only been a handful of confirmed cases involving the delta variant in the city.

Most cases still involve alpha variant

While Ontario's COVID-19 cases are decreasing, the composition of variants among cases is changing, said Day.

The alpha variant still makes up an estimated 85 per cent of the province's cases, but the delta variant is becoming more prevalent — and the transition is happening at roughly the same pace that alpha displaced the previous coronavirus that dominated cases through 2020, Day said.

Exponential growth of the alpha variant earlier this year led to the pandemic's deadly third wave and caused the province to shut down again in April.

While the transition from alpha to delta could happen before the end of the summer, the timing is trickier to predict, Day said, because modelling must take into account the pace of vaccination.

Currently, more than 65 per cent of Ontario's adult population is vaccinated with a single dose, while five per cent have received a second dose.

"It's still a race," Day said. "But fortunately, at this point, we have a much better position to win the race than we did in the beginning of the year."

'Definitely concerned'

The COVID-19 Science Advisory Table has been considering recommendations to focus second doses on hot spots where delta seems to be making a breakthrough.

"It's definitely on my radar. I am definitely concerned," said Doug Manuel, a member of the advisory table and a senior scientist at The Ottawa Hospital, on CBC Radio's All In A Day.

Members of the science table have been monitoring whether some aspects of the June 14 reopening should now be delayed a little longer, Manuel said, even as Premier Doug Ford has mused about moving the date up.

Manuel shared an example of how in Yellowknife, where 60 per cent of residents have had two doses of the Moderna vaccine, a recent outbreak of alpha variant cases still forced schools to shut down.

Two-dose vaccination rates will need to be "quite a bit higher" to avoid delta variant outbreaks, he said, and the question is whether Ontario can vaccinate people quick enough to keep the new variant at bay.

"The general feeling is that this should be an easier race to win than we had in February [with the alpha variant]," said Manuel. "But we're still not certain."