Vaccine rollout in Israel causes some concern
First dose by itself might not be as effective as originally thought
News out of Israel that the first dose of the Pfizer-biontech vaccine might not be as effective against COVID-19 as initially hoped has caused ripples of concern among Montreal's medical community.
On Monday, Israel's coronavirus czar, Nachman Ash, reportedly said the first dose of the vaccine appeared “less effective than we had thought.”
In remarks reported by Army Radio, Ash added that the protective effect of the vaccine against SARS-COV-2, the virus that causes COVID -19, was “lower than Pfizer presented.”
Since December, Israel has administered the first shot to two million citizens, or nearly 25 per cent of its population.
In addition, 400,000 residents have received the second dose.
On Monday, Israel posted a record 10,000 COVID-19 cases and the country is extending its lockdown until the end of January.
Quebec and other jurisdictions around the world have been delaying giving the second Pfizer shot, amid short supplies, after the U.K.'S Joint Committee on Vaccination and Immunization concluded that the efficacy of the vaccine was 89 per cent, starting 14 days after the first dose.
But a “real world” analysis of the vaccine by Clalit, Israel's largest health provider, has found that the chance of a person being infected with the coronavirus dropped by 33 per cent 14 days after they were given the first shot. However, the Times of Israel reported that another health provider, Maccabi, observed the vaccine caused a 60-per-cent drop in the chances of infection after the first dose.
Christina Antoniou, director of corporate affairs for Pfizer Canada, declined to comment on the latest Israeli findings.
“Our Phase 3 study demonstrated that although partial protection from the vaccine appears to begin as early as 12 days after the first dose, two doses of the vaccine are required to provide the maximum protection against the disease, a vaccine efficacy of 95 per cent,” she said in a statement. “There are no data to demonstrate that protection after the first dose is sustained after 21 days as (a) majority of individuals (in the study) received the second dose.”
A senior Montreal health official, who has been monitoring the situation in Israel closely, suggested it's too early to draw conclusions about the Israeli results.
“The place is a mess,” the official said of Israel. “The problem is nobody knows when the vaccine is going to put a dent on things. I would think it would be at least six weeks” after Israel launched mass vaccinations on Dec. 20. (The Montreal official agreed to be interviewed on condition of anonymity because of the sensitivity of the issue.)
Reacting to the latest news out of Israel, David Fisman, an epidemiologist with the Dalla Lana School of Public Health at the University of Toronto, responded in an email to the Montreal Gazette that “I think we have to see how things play out in the days ahead.”
Dr. Caroline Quach, an infectious-diseases expert at Ste-justine Hospital and a member of the National Advisory Committee on Immunization, said she was neither surprised nor disappointed to learn of the Israeli findings.
“What you have to realize is that when you calculate vaccine effectiveness at 14 days (after getting the first shot), your immune system is not yet ready and you're not (fully) protected by the vaccine,” Quach explained.
In the Pfizer clinical trial, she added, “you had a lot of (COVID -19) cases that occurred in the first 14 days post-vaccine and it's because your immune system has not yet developed antibodies to protect you. Looking at 14 days is a bit too short.”
Quach noted that Pfizer calculated that vaccine efficacy was 52 per cent for the first dose within the first 14 days. The U.K. committee, on the other hand, analyzed the same data on the first doses after the 14-day mark and came up with an efficacy rate of nearly 90 per cent.
For the Israeli authorities to observe a 33-per-cent drop in the number of cases is good, Quach continued. “We're not expecting that at 14 days we're going to have a 90-per-cent reduction in cases because it's just too early.”
What's more, Quach pointed out that the 33-per-cent rate is within the so-called confidence interval of Pfizer's study.
Still, Quach acknowledged that administering the vaccine in the midst of widespread community transmission is far from ideal.
“If you want a vaccine program to be super effective, you have to give it early on in the rise in the (epidemiological) curve. If you're giving it when the curve is already at its plateau and it's starting to decrease anyway, you'll never be able to say if it's because of the vaccine or because of the lockdown.”
Officials in Health Minister Christian Dubé's office and the Quebec Health Ministry did not respond to request for a comment on the Israeli results.