The headline of Bangladesh Cluster RCT is:

Surgical masks work, but cloth masks FAIL in cluster RCT:
We used the wrong mask b/c we didn't do this trial sooner!!!!

Symptoms without blood Ab is useless endpt.
This is the key finding 👇👇👇 pic.twitter.com/OmFteBq80N

— Vinay Prasad MD MPH (@VPrasadMDMPH) September 1, 2021