https://www.sciencedaily.com/releases/2021/01/210113090906.htm

The research, published in Annals of Internal Medicine, has immediate significance as college semesters are poised to start again -- and as the distribution of approved vaccines lags behind goals.

The study found that a combination of just two common measures -- distancing and mandatory masks -- prevents 87% of campus COVID-19 infections and costs only $170 per infection prevented.