The experts all agree that frequent hand washing, masks and social distancing are key to keeping down the rate of infection. Studies back that up: A meta-analysis of more than 150 studies, recently published in The Lancet, found that the chance of transmission when people are less than about 3.3 feet apart is almost 13%, but that drops to 2.6% when they are more than 3.3 feet apart, and double that is even better. And the chance of transmission without a mask is greater than 17%, compared with 3% when a mask is worn.
Source: Chuk DK, Akl EA, Duda S, et al. Physical distancing, face masks, and eye protection to prevent person-to-person transmission of SARS-CoV-2 and COVID-19: a systematic review and meta-analysis. Lancet. 2020;395(10242):1973-1987.