Evidence supporting the COVID-19 vaccine’s effectiveness weeks after its first injection is piling up, Canada’s top public health official says.
On Tuesday, Dr. Theresa Tam called the figures “incredible,” and said “over two months of data and beyond” showed sustained efficacy among COVID-19 vaccines even after a “significant number of weeks.”
The news comes as provinces and territories grapple with whether to lengthen the window between first and second shots.
Tam’s comments echo a number of studies that have emerged over the last few months that experts have pointed to as justification to delay the second dose in an attempt to reach herd immunity faster.
Modelling headed by Saskatchewan’s Dr. Graham Jurgens and German modeller Kyle Lackner released Tuesday estimated delaying the second dose four months would help population in high density areas reach herd immunity between five and six weeks sooner, with an average population immunity about 20 per cent higher, relative to standard three or four-week spacing.
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A re-analysis of Pfizer’s clinical trials published in the New England Journal of Medicine last month, in which two Canadian researchers said the results showed a “highly protective” efficacy of 92.6 percent beginning two weeks after the first injection.
Another study analyzing the long-term effects of a single dose of the AstraZeneca vaccine found delaying the second shot by 12 weeks or more still resulted in an efficacy of 81.3 per cent.
The news comes as the National Advisory Committee on Immunization assesses the time intervals between the first and second doses of authorized vaccines in Canada, including Pfizer-BioNtech’s, Moderna’s and AstraZeneca’s, which was approved on Friday.
Tam said the committee is expected to provide recommendations this week.
5:44 What can seniors expect after getting a COVID-19 vaccination?
What can seniors expect after getting a COVID-19 vaccination?
Several provinces have already extended the window between the first and second doses in order to fast-track the number of Canadians receiving their first dose of the COVID-19 vaccine.
The largest thus far is in British Columbia, which announced it would increase the gap from up to 28 days to 112 on Monday.
Colin Furness, an epidemiologist with the University of Toronto, called the move “aggressive,” adding that it was both “dangerous” and “risky” to veer off from recommended timeframes.
“When the vaccines were validated or tested, they were tested according to a certain schedule,” he said. “When you lengthen it, you go into uncharted territory.”
Without enough concrete evidence to fully understand the effects of delaying doses, Furness warned of several things that could happen.
Waiting several extra weeks to administer the second dose could lower the vaccine’s effectiveness, he said, or the body might shut down its immune response after so long and produce a completely different effect. Or it could make the vaccines even more effective than anticipated.
According to Furness, all options are possible until the vaccine’s long-term effects can be properly studied.
“We’re trying to make COVID go away. If getting everyone a single shot faster makes COVID go away faster, you actually end up with a better outcome,” he said.
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“The reasoning is quite clear why to delay the second shot. The question, though, is, does that then mean that we need a third or fourth?”
The race to vaccinate Canada’s population has been ramping up, made more urgent by the emergence of COVID-19 variants across the country.
As of March 1, Tam said health officials had detected 1,351 cases of the virus variants, with 1,257 cases of the B.1.1.7 strain first discovered in the U.K. accounting for the bulk of confirmed infections. No province has been spared.
However, she added that Canada was “gaining more ground every day” with the authorization of more vaccines.
“We now have (three) different COVID-19 vaccines with unique advantages, but all contributing to the reduction of severe COVID-19 illness and death in Canada,” she said.
HALIFAX – The Nova Scotia government says it could be months before it reveals how many people are on the wait-list for a family doctor.
The head of the province’s health authority told reporters Wednesday that the government won’t release updated data until the 160,000 people who were on the wait-list in June are contacted to verify whether they still need primary care.
Karen Oldfield said Nova Scotia Health is working on validating the primary care wait-list data before posting new numbers, and that work may take a matter of months. The most recent public wait-list figures are from June 1, when 160,234 people, or about 16 per cent of the population, were on it.
“It’s going to take time to make 160,000 calls,” Oldfield said. “We are not talking weeks, we are talking months.”
The interim CEO and president of Nova Scotia Health said people on the list are being asked where they live, whether they still need a family doctor, and to give an update on their health.
A spokesperson with the province’s Health Department says the government and its health authority are “working hard” to turn the wait-list registry into a useful tool, adding that the data will be shared once it is validated.
Nova Scotia’s NDP are calling on Premier Tim Houston to immediately release statistics on how many people are looking for a family doctor. On Tuesday, the NDP introduced a bill that would require the health minister to make the number public every month.
“It is unacceptable for the list to be more than three months out of date,” NDP Leader Claudia Chender said Tuesday.
Chender said releasing this data regularly is vital so Nova Scotians can track the government’s progress on its main 2021 campaign promise: fixing health care.
The number of people in need of a family doctor has more than doubled between the 2021 summer election campaign and June 2024. Since September 2021 about 300 doctors have been added to the provincial health system, the Health Department said.
“We’ll know if Tim Houston is keeping his 2021 election promise to fix health care when Nova Scotians are attached to primary care,” Chender said.
This report by The Canadian Press was first published Sept. 11, 2024.
ST. JOHN’S, N.L. – Newfoundland and Labrador‘s chief medical officer is monitoring the rise of whooping cough infections across the province as cases of the highly contagious disease continue to grow across Canada.
Dr. Janice Fitzgerald says that so far this year, the province has recorded 230 confirmed cases of the vaccine-preventable respiratory tract infection, also known as pertussis.
Late last month, Quebec reported more than 11,000 cases during the same time period, while Ontario counted 470 cases, well above the five-year average of 98. In Quebec, the majority of patients are between the ages of 10 and 14.
Meanwhile, New Brunswick has declared a whooping cough outbreak across the province. A total of 141 cases were reported by last month, exceeding the five-year average of 34.
The disease can lead to severe complications among vulnerable populations including infants, who are at the highest risk of suffering from complications like pneumonia and seizures. Symptoms may start with a runny nose, mild fever and cough, then progress to severe coughing accompanied by a distinctive “whooping” sound during inhalation.
“The public, especially pregnant people and those in close contact with infants, are encouraged to be aware of symptoms related to pertussis and to ensure vaccinations are up to date,” Newfoundland and Labrador’s Health Department said in a statement.
Whooping cough can be treated with antibiotics, but vaccination is the most effective way to control the spread of the disease. As a result, the province has expanded immunization efforts this school year. While booster doses are already offered in Grade 9, the vaccine is now being offered to Grade 8 students as well.
Public health officials say whooping cough is a cyclical disease that increases every two to five or six years.
Meanwhile, New Brunswick’s acting chief medical officer of health expects the current case count to get worse before tapering off.
A rise in whooping cough cases has also been reported in the United States and elsewhere. The Pan American Health Organization issued an alert in July encouraging countries to ramp up their surveillance and vaccination coverage.
This report by The Canadian Press was first published Sept. 10, 2024.
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