WASHINGTON — By now we've all heard that the Pfizer COVID-19 vaccine has an efficacy rate of 95%, Moderna of 94%, and Johnson & Johnson about 66%; what you may not have known is that rate's technical ...

Joseph G. Allen is an associate professor and director of the Healthy Buildings program at Harvard University’s T.H. Chan School of Public Health. Parham Azimi is a research fellow in the exposure, ...