From some reason, this @BusinessInsider article from Feb 23rd is making the rounds today on social media: https://www.businessinsider.com/new-data-calls-into-question-delaying-2nd-coronavirus-vaccine-dose-2021-2">https://www.businessinsider.com/new-data-...

The sensationalist headline "Scotland& #39;s vaccine rollout suggests delaying the 2nd #COVID19 shot is a bad idea" requires some serious nuance.

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The news article references a Feb 19th pre-print: https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3789264

This">https://papers.ssrn.com/sol3/pape... means that the study was neither peer-reviewed nor finalized when posted.

The pre-print reported a combined 58% vaccine effectiveness for #Pfizer and #AstraZeneca starting 42 days after 1 dose.

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This pre-print went on to be peer-reviewed and published last week in @TheLancet: https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(21)00677-2/fulltext

https://www.thelancet.com/journals/... href="https://twitter.com/TheLancet">@TheLancet study reported a combined 74% vaccine effectiveness for #Pfizer and #AstraZeneca starting 42 days after the first dose (77% for the #Pfizer vaccine alone).

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@TheLancet study reported a combined 74% vaccine effectiveness for #Pfizer and #AstraZeneca starting 42 days after the first dose (77% for the #Pfizer vaccine alone).3/6" title="This pre-print went on to be peer-reviewed and published last week in @TheLancet: https://www.thelancet.com/journals/... href="https://twitter.com/TheLancet">@TheLancet study reported a combined 74% vaccine effectiveness for #Pfizer and #AstraZeneca starting 42 days after the first dose (77% for the #Pfizer vaccine alone).3/6" class="img-responsive" style="max-width:100%;"/>

The U.K. has seen remarkable control of the pandemic with a strategy maximizing first vaccine doses for as many as possible.

Modelling work led by @BeateSander shows that such an extended dose interval strategy will also save more lives in Canada: https://www.medrxiv.org/content/10.1101/2021.04.07.21255094v1

4/6">https://www.medrxiv.org/content/1...

Sharing this article without proper context and fear-mongering statements are harmful.

Of course it is important to continuously evaluate and update Canada& #39;s vaccine strategy as new data emerges— @cdavidnaylor and @BogochIsaac have written about this: https://www.theglobeandmail.com/opinion/article-when-it-comes-to-vaccine-delivery-we-need-a-very-canadian-compromise/

5/6">https://www.theglobeandmail.com/opinion/a...

This includes determining which populations:

1. Require two doses following the same interval as the clinical trials
2. Should be prioritized for earlier second doses

#NACI has compiled and reviewed the existing evidence on extended dose intervals: https://www.canada.ca/en/public-health/services/immunization/national-advisory-committee-on-immunization-naci/extended-dose-intervals-covid-19-vaccines-early-rollout-population-protection.html

6/6">https://www.canada.ca/en/public...