OTTAWA – The Public Health Agency of Canada says the advice coming from a federal panel of medical experts that second COVID – 19 vaccine doses should be delayed by up to four months is meant to “complement, not mirror” the official Health Canada authorizations for use of these vaccines.
Seeking to offer some clarity around the role Canada’s National Advisory Committee on Immunization (NACI) ‘s COVID – 19 vaccine usage advice is supposed to play, Deputy Chief Public Health Officer Dr. Howard Njoo said Thursday that the difference in messaging from the two national bodies is different by design.
However, he did not offer clarity on which set of directives provinces should follow when plotting their ongoing vaccine rollout strategies . CTVNews.ca has reached out to Health Minister Patty Hajdu’s office for further clarity on whether the federal government backs NACI’s advice.
“You have likely noticed that NACI’s recommendations are sometimes different, possibly broader or narrower than the conditions of vaccine use that Health Canada has authorized. As the regulator, Health Canada authorizes each vaccine for use in Canada according to factors based on clinical trial evidence, whereas NACI bases its guidance on the available and evolving evidence in a real-world context, including the availability of other vaccines, ”Njoo said .
Late Wednesday, NACI issued new guidance advising that the window between shots for all three of the currently approved vaccines — Pfizer-BioNTech, Moderna, and AstraZeneca — can now be considerably extended, while still being effective.
While NACI’s advice are recommendations and not rules, which allows provinces to continue to tailor their vaccination rollout campaigns to fit the pandemic reality in each region, the new suggested approach has already been adopted by several provinces in recent days.
The approach of holding off on administering all second doses by four months is in contrast to what Health Canada’s authorization of these vaccines initially indicated: that the seco nd Pfizer dose was to be delivered around 21 days after the first, that the second Moderna shot was to be given around 28 days after the first, and that the AstraZeneca second dose should be given between four and 12 weeks after the first.
NACI’s new guidance makes the case that with limited supply of COVID – 19 vaccines, prioritizing first doses would allow jurisdictions to maximize the number of people being immunized with a first dose offering an initial amount of immunity earlier on.
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NACI says it’s come to this conclusion after considering evidence from recent scientific studies and “real world effectiveness, ”that show high levels of protection after one shot. Though the data remains limited and is still evolving around the best time frame to administer the first and second shots of the three currently approved vaccines, which are all two-dose regimens.
Njoo said that NACI will continue to monitor evidence on the effectiveness of a delayed second dose and “will adjust recommendations as needed.”
The infectious diseases, immunology, pharmacy, epidemiology, and public health experts who make up this advisory body are considered arms-length to the government. The panel makes recommendations to the Government of Canada for the use of vaccines approved for use in Canada based on analysis of “the best current available scientific knowledge at the time.”
The body has been in existence since 1964 advising on various new vaccines, but since the onset of the pandemic, it has been predominately focused on COVID – 19 vaccines and the prioritization of them. It reports to the Infectious Disease Prevention and Control Branch of the Public Health Agency of Canada.