Double masking works, says CDC study

Masks can help prevent the spread of COVID-19, which is something health officials have been saying with some regularity since last April.

But as a way to avoid infection from new variants, the Centers for Disease Control and Prevention offered some new suggestions based on a new study. One is wearing a cloth mask over a medical procedure mask. The other involves looping and tucking to make a surgical-style mask fit tighter.

CDC researchers experimenting in a lab found that the better the fit of the mask, the better the protection it provides.

The agency’s directions on forming a tight fit are a bit complicated, but knotting the ear loops of a surgical mask and tucking in the sides close to the face can reduce exposure to infectious aerosols by 95 percent. So can wearing two masks.

The agency also said that if a medical procedure mask is worn alone, using a “mask fitter” or wearing a sleeve made of sheer nylon hosiery over either a cloth or medical procedure mask also significantly improved the wearer’s protection.

What’s changing: Essentially, nothing. “I want to be clear that these new scientific data released today do not change the specific recommendations about who should wear a mask or when they should wear one,” CDC director Rochelle Walensky said. Updated guidance notes that double masking or wearing a tightly fitted surgical mask are two of the best ways to boost protection against exposure, but it doesn’t outright tell people to wear two masks.

Not every mask is the same: The CDC said if people choose to wear two masks, the best bet is a cloth mask over a surgical-style mask. But without much explanation, CDC also said not to combine an N95-style respirator with any other type of mask, or wear two respirators. Also, the study was limited and results may vary. The experiments were conducted in a lab, not in a real-world setting, with just one type of medical procedure mask and one type of cloth mask.