Should Canadian public health officials be keeping second doses of COVID-19 vaccine on ice until all high-risk people get their first shot?
It’s a possibility Dr. Danuta Skowronski, epidemiology lead for influenza and emerging respiratory pathogens at the B.C. Centre for Disease Control, is raising.
Skowronski says data shows that there is little extra protection provided by a second COVID-19 shot. And it means the majority of hospitalizations from severe COVID should already be “vaccine preventable.”
“We should not be waffling on this, it’s too critical right now,” she told Global News.
In a letter to the editor published in the New England Journal of Medicine co-authored with Dr. Gaston De Serres of the Institut National de Sante Publique du Quebec, Skowronski argues the Pfizer-BioNTech vaccine — initially said to be just 52.4 per cent effective with one dose — could also provide more than 90 per cent protection with a single shot.
According to Skowronski and De Serres, Pfizer’s own research started measuring how effective its vaccine was immediately after giving the shot, not after a two-week grace period she described as typical in vaccinology.
Using documents submitted to the U.S. Food and Drug administration, the doctors say they determined Pfizer’s vaccine is actually up to 92.6 per cent effective with a single dose.
Evidence collected on the ground to date in British Columbia from long-term care residents and inoculated health-care workers indicates a single-shot efficacy of at least 80 per cent, Skowronski said.
“What we’re showing, with that letter, is that the second dose gives very little added benefit over that first dose,” Skowronski said.
“We could be optimizing the use of the scarce vaccine supply by ensuring that all of our high risk individuals, target priority groups, get a first dose of vaccine before we double back and administer a second dose that is providing little added value to anyone at this stage.”
Skowronski stressed that she was not suggesting that second doses be dropped entirely, but that the priority should be getting first shots into the arms of people most at risk.
Pfizer is resistant to the idea of holding off on second doses.
In a reply to Skowronski and De Serres, the company insisted that “alternative dosing regimens … have not been evaluated.”
“The decision to implement alternative dosing regimens resides with health authorities; however, we at Pfizer believe that it is critical for health authorities to conduct surveillance on alternative dosing schedules to ensure that vaccines provide the maximum possible protection,” it said.
The federal government is seriously looking at the data.
Federal Health Minister Patty Hajdu was asked Friday if a single-dose regimen, combined with new research showing the vaccine could possibly be kept at a warmer temperature, could be a “game changer.”
“It could be,” she said.
“The regulators are always renewing the new data as it arrives, from both the manufacturer and our own domestic data that continues to grow.”
Health officials in B.C. are actively discussing the possibilities the data opened up.
“What we’re trying to do, what we’re all trying to do is maximize the protection from the available vaccine to the entire population,” deputy provincial health officer Dr. Reka Gustafson said.
“So I would say that the data are being looked at very, very carefully and evidence is accumulating to to support that as a potential approach for maximizing protection in the population.
The province has administered 192,942 doses of COVID-19 vaccine, of which 36,923 were second doses.
On Thursday, B.C. administered 12,250 doses of vaccine, its highest-ever single-day immunization. More than half of those shots were second doses.View link »