Read on Twitter
Interesting poll. Selection/response bias aside, majority picked a low probability, but 40% still thought there was 10+% prob that vaccines will not substantially prevent transmission. This is why I have become convinced this concern is highly unlikely (borderline implausible) 
https://twitter.com/AaronRichterman/status/1348492463229562880
https://twitter.com/AaronRichterman/status/1348492463229562880
1. Data from screening PCR at the time of the 2nd moderna mrna vaccine, showing reductions in asymptomatic PCR positivity. This is before the 2nd dose and if anything will underestimate effect. Will have additional confirmation from unblinding pcr and ab https://twitter.com/JakeJohnsonMD/status/1348665305799811072?s=20
2. Data from AZ vaccine chadox study is a mess, but they did weekly PCR screening and points in the same direction.
https://www.thelancet.com/action/showPdf?pii=S0140-6736%2820%2932661-1
https://www.thelancet.com/action/showPdf?pii=S0140-6736%2820%2932661-1
3. We aren't reinventing immunology and need to consider our priors based on experience with other vaccine-preventable infections. https://twitter.com/PaulSaxMD/status/1337149176832876544?s=20
3b. Another thread from @MonicaGandhi9 on this https://twitter.com/MonicaGandhi9/status/1347988651179798530?s=20
3c. The interesting counterargument involves requirement of IgA for upper resp tract mucosal immunity (vs IgG to prevent LRT symptomatic disease). However, as @leela_davies points out, IgG-generating vaccines prevent transmission in other resp viruses https://twitter.com/SanjatKanjilal/status/1348544271310331909?s=20
4. Even if we assume vaccines ONLY prevent symptomatic disease, turning all into asymptomatic infections, there is a solid body of evidence 
(inc systematic reviews from @mugecevik and @nicolamlow) that this alone would substantially reduce transmission https://twitter.com/AaronRichterman/status/1340285330428182529?s=20
(inc systematic reviews from @mugecevik and @nicolamlow) that this alone would substantially reduce transmission https://twitter.com/AaronRichterman/status/1340285330428182529?s=20
5. Based on this, I think the possibility that these vaccines don't meaningfully reduce transmission (to the point that populations can move back towards normal life in due course) is low enough that we should treat this as a mostly theoretical concern at this point.
6. An enduring lesson of this pandemic (& others) is the need to communicate uncertainty honestly (in both directions). Of course its reasonable to be careful, but lets not forget that this theoretical concern is being cited as a reason not to get the vax https://twitter.com/AaronRichterman/status/1348494121019826178?s=20
