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

This 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

@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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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

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