To definitively answer the question of whether face masks protect against the novel coronavirus, here’s what you’d need to do:— Recruit thousands of volunteers.— Randomly divide them into two groups.— Assign one group to always wear masks outside of the house, and one group to never wear masks.— Wait a few months, see who gets infected — then try to sort out all possible confounding variables, such as compliance, mask fit and social distancing.A study like that would be not only tough to pull off, but unethical, especially in the midst of a pandemic. It also wouldn’t be able to determine commu...
