Danish Study Doesn’t Prove Masks Don’t Work Against the Coronavirus

Q: Did a recent study in Denmark show that face masks are useless for COVID-19?

A: No. The study found that face masks did not have a large protective effect for wearers — not that masks provide no protection at all or don’t offer benefits to others. 

FULL QUESTION

Are masks proven to be useless for COVID-19?

FULL ANSWER

News of the results of a recent randomized controlled trial in Denmark testing a face mask intervention has led some to conclude that masks are ineffective against the coronavirus, or SARS-CoV-2. 

But scientists say that’s the wrong takeaway — and even the authors of the study say the results shouldn’t be interpreted to mean masks shouldn’t be worn.

The trial evaluated whether giving free surgical masks to volunteers and recommending their use safeguarded wearers from infection with the coronavirus, in addition to other public health recommendations. The study didn’t identify a statistically significant protective effect for wearers, but the trial was only designed to detect a large effect of 50% or more. And the