Vaccines are showing significant protection against COVID-19 infection, hospitalization and death so far in Ontario, according to new data from the province’s public health agency.
Public Health Ontario reported 2,223 Ontarians developed COVID-19 symptoms after receiving one or two doses of a COVID vaccine. That number represents just 0.06 per cent of the 3.5 million people in the province who had received at least one vaccine dose by April 17.
It’s the best news that infectious diseases physician Dr. Zain Chagla has heard all week, and a good sign that as more Ontarians get vaccinated, the burden on hospitals will ease and life can eventually return to normal.
The majority (66.9 per cent) of post-vaccination COVID-19 cases occurred between 0 and 14 days after the first dose, when the body is still building up immunity. Just 3.9 per cent of those who developed COVID-19 symptoms after vaccination became sick seven or more days after the second dose of a two-shot vaccine, classifying them as “breakthrough” cases.
Breakthrough cases are getting increasing attention as the global vaccine rollout ramps up, but fortunately, they’re proving very rare. An April 21 study in the New England Journal of Medicine found just two out of 417 people who had received two doses of the Pfizer or Moderna vaccines tested positive for COVID-19 and developed symptoms. On April 26, the U.S. confirmed 9,245 vaccine breakthrough infections among the more than 95 million people in the U.S. who had been fully vaccinated as of that day — about 0.009 per cent.
In another promising sign, Public Health Ontario’s data also shows vaccines are working well against the B.1.1.7 variant, which has been the dominant strain in Ontario since late March 2021. There was not enough evidence to draw conclusions about vaccine effectiveness against rare variants including B.1.351 and P.1.
Breakthrough cases are normal for any vaccine, doctors say, since no dose is 100 per cent effective. The Pfizer, Moderna and AstraZeneca vaccines are about 60 to 80 per cent effective at preventing COVID-19 infection after one dose, and more than 85 per cent after the second dose.
But overwhelmingly, the COVID-19 vaccines are preventing more severe cases of COVID-19 that end in hospitalization or death, even after one dose. Public Health Ontario reported zero deaths and six hospitalizations among people who had received two doses of a COVID-19 vaccine and 49 deaths and 155 hospitalizations among people who had gotten just one shot.
The low death and hospitalization rates are particularly promising given that a significant proportion of Ontario’s fully vaccinated population are elderly people living in long-term care, which saw devastating rates of severe illness and death from COVID-19 before the vaccine rollout. Nearly 4,000 long-term-care residents have died from the virus since last March.
“This is really changing this from a rapidly fatal disease that decimates society to a respiratory infection, which is less dangerous than other respiratory infections out there,” Chagla said.
Still, as vaccines targeted seniors and health workers in the early stages, the burden of COVID-19’s third wave shifted to younger people and essential workers, who are only just starting to get vaccinated. There are currently 2,075 COVID-19 patients in Ontario hospitals as of Wednesday, including a near-record of 882 in intensive care. Of those, 620 people are on a ventilator.
There are hurdles to come, like continuing to get vaccines to those who are most vulnerable, but the effectiveness of the vaccines “talks to how important it is for people to get the first dose they can right now,” Chagla said.
With Ontario on track to vaccinate 65 per cent of those 18 and up in the province by the end of May and more in the months to come, Chagla expects the number of COVID-19 patients in hospitals will continue to drop and the economy will slowly be able to reopen.
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COVID-19 vaccines are highly effective against infection and hospitalization, Public Health Ontario data shows - Toronto Star
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