Thread by @SammyG_MD

1/People keep asking what they can “do” now that they’re vaccinated (half of adults in Canada!). Can we follow the @CDCgov advice here in Canada too? What evidence can we use to guide us?

2/The @CDCgov has said that fully vaccinated people can attend small outdoor gatherings and even outdoor dinners without a mask, including with people who are unvaccinated.

3/The @CDCgov advice makes a lot of sense because vaccinated people are less likely to get sick – i.e. the risk of symptomatic infection for vaccinated people is much lower. And risk of severe disease is almost nil.

4/ But we also know that they are less likely to even get the virus (i.e. asymptomatic infection). After vaccination, the risk of all infections, including asymptomatic infection, is clearly lower, by up to 90%: cdc.gov/mmwr/volumes/7…

5/Finally, it was recently confirmed that even in those who do become infected, risk of viral transmission is lower - by 40-50% (even after a single vax dose) - compared to infected people who were not vaccinated (likely from lower viral load):
khub.net/documents/1359…

6/So: vaccination (even 1 shot, though less so than 2 shots) reduces symptomatic infection, asymptomatic infection, and transmission. You are unlikely to get sick, but even if you do, you are less likely to pass it on.

7/ So just being vaccinated is v. good to begin with. Now add another layer of security – being outside. Transmission in outdoor settings, barring superspreader events with yelling and close contact, is very low (about 20x lower than indoor transmission):
academic.oup.com/jid/article/22…

8/Putting all that together, it makes sense to allow vaccinated people to congregate in small outdoor gatherings, unmasked. And even for outdoor picnics/dinners unmasked. And if unvaccinated people are present, those vaccinated need not mask because they are so well protected

9/The protection is a little lower for 1 shot vs 2, but still excellent once you are 2-3 weeks post vax (>80% protection with mRNA vaccines). However, we are still learning about how long that immunity lasts between shots, and protection from variants. cdc.gov/media/releases…

10/At the end of the day, this is a balanced approach that does not aim for zero risk but acknowledges a significant reduction in risk. And a need to get back to some form of normal. A similar approach would make sense for Canada. #harmreduction

11/But maybe the most important reason to do this is that getting to herd immunity will require giving vaccine hesitant people a carrot. Some may distrust science, buy into conspiracies, obsess about risks, but presenting a path to return to normal will move many to get the shot

12/And if that doesn't work, we can always just give people $100:😜nytimes.com/2021/05/04/ups…