QUEBEC CITY – Quebec public health officials said on Thursday that provincial councilors recommended a 90-day COVID-19 vaccination schedule between the first and second doses – more than twice as much as a national advisory committee recommended the day before.
“In our context, this is the best strategy,” said Health Minister Christian Dubé at a news conference on Thursday about the progress of vaccination in Quebec.
Quebec announced in late December that it would delay second doses or “booster doses” of the vaccine, but the province had not said until Thursday what kind of delay it had in mind.
Provincial authorities now say that the second dose should come between 42 and 90 days after the first.
Such a scheme would allow the province to give the vaccine to more people who would otherwise have to wait for the first dose, health officials said.
A 90-day delay is much longer than that recommended by Pfizer (21 days for your vaccine), Moderna (28 days for your vaccine) and federal public health advisers on their recommendation on Wednesday (up to 42 days for both vaccines).
However, that national advisory panel, called NACI, said on Thursday that the provinces have some leeway to make their own decisions and do not object to Quebec’s 90-day schedule.
Canada’s Deputy Chief of Public Health, Dr. Howard Njoo, said the “exceptional circumstances” of certain provinces could mean that they need to deviate from federal recommendations.
“It is a kind of interaction between real epidemiology, on the ground, the fact that there is an obviously increased rate of cases, hospitalizations,” said Njoo, and the vaccine guidelines.
EXTENSION BASED ON ‘EXPERIENCE’, NOT DATA, SAYS QUEBEC
So why is the province talking in 90 days?
Ministry of Health adviser Dr. Richard Massé said that Quebec experts believe that immunity is likely to last more than 42 days, as recommended by the NACI panel, but the clinical trials have gone no further.
Instead, they rely on previous experience with other vaccines.
“What we have is the experience of working with many vaccines,” said Massé. “Immunity is not something that is ‘on’ or ‘off’.”
While the Quebec Ministry of Health said that a single dose can provide up to about 90 percent effectiveness against the virus, Pfizer says that a single dose is only 52.4 percent effective.
Massé told reporters that the discrepancy comes from different and more specific analyzes of Pfizer’s test data.
He said that Pfizer, in studying the subject, included people who received their first dose, but did not have time to boost immunity.
“It takes 12 to 14 days to have immunity,” said Massé. “If you count people who get the disease two, three, five days after getting the vaccine, it’s not really a vaccination failure because immunity [hasn’t been built up]. “
An expert told CTV News this week that there are wide variations in efficacy estimates due to the small sample size of people who received only the first injection in the Pfizer study. That expert, Dr. Donald Vinh, said that, in his opinion, the effectiveness is probably in the 60 to 69 percent range.
In a statement to CTV News, Pfizer Canada spokeswoman Christina Antoniou reiterated previous statements that Pfizer did not evaluate the effectiveness of its vaccine in alternative dosing schedules.
“There is no data to show that protection after the first dose is maintained after 21 days,” she said.
“We recognize that recommendations on alternative dosage intervals are up to health authorities and may include adapting public health recommendations in response to changing circumstances during a pandemic,” she wrote.
But for Pfizer, “as a biopharmaceutical company working in a highly regulated industry, our position is supported by the label and indication agreed with Health Canada and informed by data from our Phase 3 study”.
Minister Dubé said the province has been talking to Pfizer. On January 5, Pfizer told CTV News that Quebec had not informed the company before deciding to postpone the second dose.
“We had conversations with Pfizer,” said Dube, “to inform them of why we are making these decisions.”
Earlier this week, Prime Minister François Legault said that in discussions with the federal government, the province learned that there may be a risk of losing Quebec’s vaccine supply if Pfizer is not happy with its dosing regimen.
On Thursday, the Pfizer statement said the company “remains[s] committed to our ongoing dialogue with regulators, health officials and governments, and our ongoing data sharing efforts to help inform any public health decisions aimed at defeating this devastating pandemic. “
Both Massé and Dubé said they expect an increase in supply, as they favor a shorter delay before the second dose if vaccine delivery in the province increases.
“Saving lives is a moral imperative,” said Dubé.
“The more doses we have, the more we will be able to shorten the time between the first and the second dose.”
NEXT STEPS FOR QUEBEC VACCINATION
With about 65% of CHSLD residents already receiving their first dose, Dubé said Quebec will begin vaccinating residents of nursing homes (RPAs) on 25 January.
He said that with a prolonged schedule between the first and the second dose, the province may also consider vaccinating the elderly population in general earlier.
With the arrival of new vaccine shipments in the province this week, Dubé said that 115,000 people have already been vaccinated.
In total, the province has received 162,000 doses so far. Dubé says Quebec is on track to increase that total to 250,000 in February.
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Will delaying the second dose of the vaccine by 90 days work? Dr. Caroline Quach is an epidemiologist and responsible for the infection prevention and control unit at Hospital Saint-Justine, in the National Immunization Advisory Committee.
– With Kelly Greig files from CTV