Pfizer pushes back after Quebec delays second vaccine doses

covid vaccines Quebec Health and Social Services CTV

By Selena Ross, CTV News Montreal 

Quebec is under increasing pressure on vaccines—from two sides, with accusations that it needs to speed up, and also that its efforts to speed up will backfire.

Some of that pushback came from Pfizer, which told CTV News this week that Quebec should not be asserting that it’s fine to delay the booster shot for the company’s two-shot vaccine.

“It’s not accurate that this model is supported by Pfizer,” said company spokesperson Christina Antoniou.

“We can only support usage of the product according to the label and indication agreed upon with Health Canada.”

Pfizer’s second shot is meant to be given three weeks after the first, but Quebec is now using all those intended second doses to use as first doses, saying more people will get some immunity that way.

COMPLICATED DATA AND DIFFICULT TRADE-OFFS

The strategy has also been adopted elsewhere, including in the U.K. But whether data backs it up is contentious and complicated.

In announcing the move last Thursday, Quebec said research suggests the vaccine will still work even if the second shot is delayed.

Dr. Gaston De Serres, chief physician of the scientific immunization group at Quebec's national public health institute, said the first dose provides the majority of the protection against the virus. The second, he added, serves mostly to prolong that protection.

One Montreal health official later used the words Pfizer objected to, saying the strategy was “supported by Pfizer.”

Dr. Lawrence Rosenberg wrote that to residents and staff at the Maimonides care home – one of the first places in Quebec to get the vaccine – in an update explaining why they won’t be getting their scheduled second shots this week.

"Other Canadian jurisdictions have followed the same strategy of giving as many first doses as possible without holding any vaccine in reserve, Rosenberg said.

“Research has shown that the Pfizer vaccine achieves 90% effectiveness two weeks after the first dose has been administered,” he wrote. 

“The second dose is a ‘booster’ shot that enhances the already high level of protection.”

Pfizer took issue with that number, saying in a statement that the phase three trial showed that the immunity began to take effect 12 days after the first dose, but that only “52.4% vaccine efficacy was observed between dose 1 and dose 2.”

After getting the second dose, effectiveness rises to 95 per cent.

One statistic frequently cited, which may have caused some confusion, comes out of data from the American Food and Drug Administration review of the Pfizer vaccine.

It says the vaccine was shown to be 82 per cent effective for a mixed group of people who had received the first and second doses.

The Quebec health department hasn’t yet responded to a request for comment about how it settled on the new strategy. 

Pfizer said it didn’t consult the company, with Antoniou saying “the Quebec public health authorities informed us of their decision after it had been made.”

Some immunologists, however, have advocated for delaying second doses, especially in light of the virus’s mutations—wider coverage is better than perfect coverage, they’ve said, and the booster shot will likely still work if given a bit late.

The U.K. says it will delay second doses by up to 12 weeks. In Canada, the federal director of public health, Dr. Theresa Tam, says she has asked the national vaccine advisory panel to investigate if there is any merit to delaying booster shots.

Montreal doctor Christopher Labos is among those who think it’s “dangerous” to change the policy without data on what will happen. 

Very few people studied in the Pfizer trials received only one dose, he said, so the outcome is a mystery.

“Saying that one dose is as effective as a two-dose strategy really isn’t supported by the evidence, because we don’t have any evidence here,” he said. 

“Here’s the thing though, it might actually be fine… we don’t know.”

PRESSURE TO MOVE FASTER, AS QUEBEC LAGS

At the same time, aside from growing worries about virus mutation, Quebec is under the gun to vaccinate more people, fast.

A total of 32,763 doses of vaccine have been administered as of Tuesday, or about 37 per cent of doses delivered to Quebec so far overall. 

That puts the province fourth among large Canadian provinces in terms of vaccination speed, as of today. It’s behind Alberta (57 per cent of available doses administered), British Columbia (47 per cent) and Ontario (40 per cent), according to data from the COVID-19 Tracker Canada tool.

Quebec has 87,500 doses at hand: 55,000 doses of the Pfizer vaccine and 32,500 of the Moderna vaccine. More deliveries are on the way.

On Monday, 2529 doses were administered, while the most productive day was December 30, when 3,942 needles were given to Quebecers.

Quebec reached another milestone on Tuesday, however, when the CIUSSS of Central-West Montreal announced it had given out its first Moderna vaccines.

--With files from the Canadian Press

SIGN UP NOW

Stay up-to-date and in-the-know by subscribing to one of our newsletters