The Centers for Disease Control and Prevention is now recommending double-masking or tying the loops of a surgical mask for a snug fit over the face as more infectious COVID-19 variants spread across the US.
The agency released a study on Wednesday, which found that wearing a cloth mask over a surgical mask, or knotting the loops of a surgical mask and tucking in the extra material closer to the face, offered far more protection than the surgical mask alone when worn regularly. The research showed that transmission of the virus could be reduced by up to 96.4% if both an infected person and an uninfected person wore two masks or a well-fitted mask.
At a White House press briefing on Wednesday, CDC Director Rochelle Walensky said the agency recommends that masks fit snugly against the nose and have two or more layers that completely cover the nose and mouth.
Any type of mask will provide more protection than no mask at all, but a well-fitted mask is better at blocking the tiny water particles called aerosols that are emitted while breathing, as well as blocking exposure to aerosols from others, she said.
Wearing a mask with a flexible wire over the nose, folding the ear loops on a mask, or wearing a cloth mask over a disposable mask can help improve the fit. The CDC also recommends mask fitters, which are plastic frames often constructed to an individual's face shape that sit over a mask for a tighter fit.
"Bottom line is this," Walensky said. "Masks work, and they work better when they have a good fit and are worn correctly."
News about extra-contagious coronavirus variants emerging in the US has troubled scientists, even as vaccine distribution ramps up. The CDC has emphasized the importance of maintaining safety measures — especially using a better-fitting mask — until most of the population is vaccinated.
Experts have told BuzzFeed News that having a snug-fitting mask or double-masking is crucial to keeping out airborne viruses.
"Having a gap is like having a hole in the mask," said Linsey Marr, a professor of civil and environmental engineering at Virginia Tech, about the fit of a mask.
Alex Huffman, an aerosol scientist at the University of Denver in Colorado, also said that wearing a well-fitted mask "forces the air to go through the material," which could block the spread of viruses.
The vaccines seem to be effective against some of the new variants. However, some experts fear that the speed at which the virus is mutating may eventually surpass the efficacy of the vaccines.
Dan Vergano contributed reporting to this story.