Canada experts recommend 4-month interval between 2 Covid-19 vaccine doses

Health experts in Canada have recommended that the interval between two Covid-19 vaccine shots can be extended to four months in order to quickly cover the entire population with the first dose of the vaccine amidst doses shortage.

Canada's National Advisory Committee on Immunization (NACI) formulated new guidelines suggesting that the time frame between shots for all three of the currently approved vaccines—Pfizer-BioNTech, Moderna, and AstraZeneca—can now be considerably extended, while still being effective.

“NACI recommends that in the context of limited Covid-19 vaccine supply, jurisdictions should maximize the number of individuals benefiting from the first dose of vaccine by extending the interval for the second dose of vaccine to four months,” said the advisory body in an official statement.

“Extending the dosing interval to four months allows NACI to create opportunities for protection of the entire adult population within a short timeframe. This will not only achieve protection of the adult population but will also contribute to health equity,” NACI recommended.

The authority believes that if the four-month interval is implemented, approximately 80 per cent of the eligible population could be offered a Covid-19 vaccine dose by the end of June, leaving second doses to begin being administered in July.

“The first two months of real-world effectiveness are showing sustained high levels of protection. Extending the interval between doses was shown to be a good strategy through modeling,” said NACI.

According to the CTV Canada news report, the new recommendations are in contrast with what Health Canada’s authorisation stated. The authority believes that the second Pfizer dose was to be delivered around 21 days after the first. While the second Moderna shot was to be administered around 28 days after the first. And the AstraZeneca second dose should be administered between four and 12 weeks after the first.