After having suffered criticism on the speed of deployment of the third doses, Quebec presses on the accelerator. Not only are the booster doses offered to all adults as of Friday, but people recovered from COVID-19 can now get their vaccine “as soon as their disease is resolved”, despite a contrary opinion from the National Institute of Health public of Quebec (INSPQ).
Officially, this decision to offer a third dose more quickly to people cured of COVID-19 is based on “a recommendation from Public Health”. However, it contradicts a scientific opinion from the INSPQ published just before the holidays. “A booster dose to someone who has already received two doses of the vaccine and had a confirmed infection is of little help. […] An interval of three months between the last dose or infection and the booster dose would be ideal, with a minimum interval of eight weeks, ”it was stated.
“This period after infection seems a little short to me,” says virology specialist Benoit Barbeau. But, since we are not short of doses, more is better than not enough. “
The benefits of this third dose after infection therefore appear to be rather low. On the other hand, the risks seem just as limited. “There may be a few more frequent side effects, but not serious enough to my knowledge,” notes Mr. Barbeau.
“I do not believe that there are significant risks in receiving a dose of vaccine shortly after having COVID-19, confirms the director of the Department of microbiology-infectiology and immunology at Laval University, Louis Flemish. […] Vaccinating immediately after COVID-19 will still increase the amount of antibodies to a higher level, even if this is not the optimal situation from an immunological point of view. The situation with Omicron is such that it is preferable to have as many antibodies as possible quickly, at a time when the virus is very present in the population and is spreading at high speed. “
This measure seems to indicate that the government wants to standardize the health passport to three doses as quickly as possible. “When the entire population has had the opportunity to receive its booster dose, the status” adequately protected “for the vaccine passport will increase to three doses,” said the government press release in the “Highlights” section.
An interval of three months between the second dose and the booster dose must however be respected, mentions Quebec.
Pfizer for young people
In vaccination clinics, an air of déjà vu floats around these third doses. Some patients show up for their appointment, but in front of a syringe filled with Moderna’s vaccine, they refuse the injection and turn back, fearing to “mix” their first two doses of Pfizer’s vaccine with that of another manufacturer.
These refusals remain “marginal”, assure the persons in charge of vaccination of several CIUSSS, although these reluctance require explanations which slow down the process.
However, these two “interchangeable” vaccines, as the government says, are not quite the same. The booster dose of Pfizer is only offered to under 30s, while the Moderna booster is given primarily to seniors.
It is that heart problems “occur more frequently in men 18 to 29 years after the administration of the second dose” of Moderna, indicates a public health opinion. Episodes of myocarditis or pericarditis affect 33.2 individuals per 100,000 people for the Moderna vaccine, against a ratio of 14.2 / 100,000 for that of Pfizer, according to Quebec data.
Some preliminary studies suggest that an interaction between vaccines and testosterone would explain this difference, notes Alain Lamarre, researcher in immunology and virology at the National Institute for Scientific Research. “Moderna gives a little more side effects, it’s been known from the start. These are side effects that are reversible and treatable, ”he adds.
Besides these more intense unpleasant consequences after injection of Moderna’s product, the levels of effectiveness of the two products remain very similar. “On the other hand, these are data that date from other waves, before Omicron. Is it the same for Omicron? To my knowledge, there is no data for Omicron. “
“I expect to have all three,” says Lamarre. I had AstraZeneca first, Pfizer second, and probably Moderna third. The vaccine trilogy! And that doesn’t worry me at all. Even that there is a theoretical advantage to having mixtures. It stimulates different pathways, different cells. “
Quebec currently has 2.5 million doses of the Moderna vaccine and 700,000 doses of the Pfizer vaccine. Almost 100,000 third doses were injected in the province yesterday.