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How Effective Are Cloth Masks?

This illustration shows a woman wearing two facemasks, a cloth mask over a surgical mask.

This illustration shows a woman wearing two facemasks, a cloth mask over a surgical mask.

Photographer: OLIVIER DOULIERY/AFP

In this week's edition of the Covid Q&A, we look at the efficacy of masks. In hopes of making this very confusing time just a little less so, each week Bloomberg Prognosis is picking one question sent in by readers and putting it to experts in the field. This week's question comes to us from Laura in Minneapolis. Laura is vaccinated and wants to better understand just how effective cloth masks are at both protecting herself from contracting Covid and at preventing the spread of it. She asks: 

What does the research show about effectiveness of wearing a cloth face covering?

First, vaccinated or not, masks are still critical. The delta variant is highly contagious and still spreading. Masks and social distancing are an important part of the push to slow the spread of Covid-19—especially with nearly a quarter of eligible Americans still holding out on getting a shot. 

Now, let’s talk about mask efficacy. For that, we turn to Ashley Styczynski, an infectious disease fellow at Stanford University who recently co-authored a large-scale study looking at that very question