The Ever-Shifting Pandemic: New Advice on Masks

Single-layer athletic gaiter-type masks no longer recommended.

Do you remember the very beginning of the pandemic? Medical leaders urged members of the public that masks were unnecessary for those without symptoms. As our understanding of COVID-19 grew, and we came to realize that even people without symptoms could spread the virus, we quickly changed the message. Masks are necessary whenever we are near those we don’t live with.

The entire time, healthcare organizations have been concerned with providing an adequate number of masks for our healthcare teams, so we encouraged the members of the public to use handmade cotton masks. While we determined that bandanas and neck “gaiters,” made out of a lightweight, breathable fabric favored by runners and cyclists, may not be perfect, it was logical to assume that they would be better than nothing. We shared this information with the public.

Just as much about our understanding of the virus continues to grow, so does our concept of masks and the differences in how well they work. An exploratory study published late last week in Science Advances examined the effectiveness of 14 different types of masks and face coverings. The study used laser beams and a cell phone camera to determine how many droplets escape while talking through each.

The good news is that N95s without valves, like those we use in the hospital, are excellent virus stoppers. They let through zero droplets. Surgical masks, which are also used in the hospital and medical practice settings, were a very close second.

Remember that masks protect the people the wearer is exposed to rather than the wearer themselves. So, these medical-grade masks are exceptionally important for patient safety. And, while it may be tempting to go purchase all you can, unless you are in frequent contact with those who are at high risk, we ask that you leave these very effective masks for healthcare providers, who need to take special precautions when treating those who are ill.

The cotton and cotton-blend masks filled the next five slots in order of effectiveness. The eighth spot was a valved N95, the type with the hole in the front, followed by more types of cotton masks.

The last four in effectiveness were knitted masks, bandanas, no mask at all, and neck gaiters, referred to in the study as fleece.  That’s correct. Neck gaiters appear to be worse than nothing. How these microfiber gaiters somehow amplify the droplets is still unknown. The study counted the number of particles, rather than their size, so is likely that the gaiter diffuses large particles into smaller ones.

The authors of the study acknowledge all of the ways that the study is limited. It was the first time the effectiveness of masks was evaluated in this way, and some improvements are needed. The surprising nature of the results will certainly prompt additional study.

For now, we are grateful to learn that it appears the masks we use to ensure patient safety are the best available. And, sadly, I have to change my recommendations and those of the health system again. Where we had once thought that a bandana or gaiter was plenty good enough, we’d now like to encourage everyone to get a cotton or cotton-blend mask. The number of layers of fabric seem to be especially helpful in blocking droplets.

As we continue to learn together, there is likely to be more updates to our understanding of COVID-19 and how to deter it. We will be certain to share them with you as soon as we learn about them.