While several health authorities around the world recommend that governments vaccinate their population as massively as possible with the first dose of available vaccines, the rapid transmission of new, more contagious variants of COVID-19 could thwart their strategy.
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Other experts are concerned about the actual immunity obtained after the injection of the first dose and whether it would prove to be effective enough to protect against variants of COVID-19. This is the case of the professor of biochemistry at the University of Montreal, Dre Nathalie Grandvaux.
“We don’t have a lot of data on what type of immunity the first dose actually triggers because, in the companies’ phase 3 trials, there are very few participants who did not receive the second. dose, ”she says.
However, data from the UK shows that the first dose does not trigger immunity in more than half of people over 80, while it is triggered in all cases after the second dose.
“It worries me particularly because we want to protect our seniors, especially in CHSLDs and retirement homes,” says Dre Grandvaux.
According to her, the government should seriously consider the option of administering the second dose as quickly as possible to this clientele at risk, as provided for in the protocols developed by the pharmaceutical companies.
“With the data that is available, this is what I would recommend, to give this second dose within the time limits prescribed by the companies as much as possible,” she says.
Remember that for the Pfizer / BioNTech vaccine, the injection of the second dose is scheduled 21 days after the first. For Moderna, this period is 28 days.