For those who have received dose #1 of AZ & wondering "what now"? Don't despair. Your 2nd dose protocol will be almost certainly be a very safe & reasonable one. The decision will be based on both supply & evolving trial data. Let me explain. 1/

As said before, AZ is the only vaccine with trial evidence of efficacy beyond a 28 d interval (up to 12 wks). Nobody knows for sure but stretching that to 16 is likely ok for those < 65 or immune compromised. But "likely" isn't enough. I get it. 2/

To date in Canada, a little over 2.3 M doses of AZ have been delivered but supply is dwindling for 2 reasons. First, we are getting a lot of mRNA vaccines soon! About 2 M Moderna in next 2 wks, 2 M Pfizer EVERY wk till July 3/

The COM-COV trial in UK studying mixed vaccine platform should have results from AZ-Pfizer mix sometime later this month. Other mixed platform data is expected in July. So this won't be a "population experiment" if applied 4/

I'd be willing to bet that most of you in Canada who got AZ dose #1 will get a Pfizer dose #2. We use different mechanisms to pair vaccine regimens all the time (eg. Pneumovax + Prevnar for Pneumonia). Not only safe but works better! 5/

Clearly we still have to prioritize seniors, immune compromised to receive 2nd doses ASAP (and before kids). NACI is deliberating right now. Expect new guidelines very soon. Hopefully the next presser is memorable for the right reasons. 6/

So again. Don't despair. There is REAL hope being generated here and real prospects for a safer, more enjoyable end of 2021. If you get a chance, please jump on it. Come on. Let's do this Canada !
#DontWaitBeGreatVaccinate