"Indirect" effectiveness of 42.9% to unvaccinated household member 10 weeks after 1st dose. Vax leads to a substantial reduction in infections among unvaccinated household members consistent with what we know of transmission after vax (many studies show this) pic.twitter.com/OxMXCAPLpP

— Monica Gandhi MD, MPH (@MonicaGandhi9) May 31, 2021