Can Surgical Masks Protect Against COVID-19 ? Wear a Scarf!

(CNN) New coronavirus cases in California and Oregon are second and third of unknown origin in U.S. has a video, titled “Doctor says your mask won’t help you against corona virus. Here’s why.” Anderson Cooper interviews a pediatrician, who says as much. This is followed by (CNN) Masks can’t stop the coronavirus in the US, but hysteria has led to bulk-buying, price-gouging and serious fear for the future. Quoting,

“The CDC says that healthy people in the US shouldn’t wear them because they won’t protect them from the novel coronavirus.”

Scarfing up surgical masks when healthcare system has a critical shortage is antisocial. The priority of masks for healthcare workers is for our collective benefit. This does not justify assertion of a fact that does not exist. There is modest evidence that surgical masks offer risk reduction. But there is now a tendency, ranging across the media, and including VP Pence, to manage this subject for the wrong reason, to prevent panic.

The correct statement is that nobody knows for certain whether surgical masks are protective. A study of  mask use by clinicians to protect from general upper respiratory infections, including flu, suggests, with a caveat, that they are. See (NCBI PMC) Effectiveness of N95 respirators versus surgical masks in protecting health care workers from acute respiratory infection: a systematic review and meta-analysis.

This is a meta study, which extracts new information from prior studies by fancy math. The article acknowledges that at the objective level, in the lab, N95 masks filter infectious particles, while surgical masks do not. Yet from the section Interpretation,

“Results of our systematic review and meta-analysis show that there was no significant difference between N95 respirators and surgical masks when used by health care workers to prevent transmission of acute respiratory infections from patients.”

The caveat:  The article authors note that the study has low statistical power, meaning that there is a more than negligible chance that the above conclusion is false.

Follow the logic: If N95 masks protect, and surgical masks work about as well in clinical settings, then surgical masks protect. Remember the caveat. Now translate that into unmanaged news-speak:

Surgical masks might offer some level of protection, but nobody knows for sure.

How do we explain the apparent discrepancy of lab tests versus clinical experience? An easy guess: While the mask doesn’t stop droplets, it changes the physics of the inhaled air stream. It reduces the formation of vortices (rotation in the air stream, see vortex) that rip at the delicate mucous lung lining,  and enhance transport particles deeply into the lungs.

That’s what I would like to see. Treat people like adults, and they are more likely to act as such. Even if you’re into managing, there is another reason to avoid it: If and when the shit hits the fan, they are more likely to follow your lead.

Don’t believe everything a doctor tells you. You just got a second opinion. A surgical mask could also prevent you from being smacked by gobs. I’m not waiting for the study.

An ethical alternative: Wear a scarf. (Oxford Academic, Annals of Work Exposures and Health) Simple Respiratory Protection—Evaluation of the Filtration Performance of Cloth Masks and Common Fabric Materials Against 20–1000 nm Size Particles. From the abstract,

“A shortage of disposable filtering facepiece respirators can be expected during a pandemic respiratory infection such as influenza A. Some individuals may want to use common fabric materials for respiratory protection because of shortage or affordability reasons. To address the filtration performance of common fabric materials against nano-size particles including viruses, five major categories of fabric materials including sweatshirts, T-shirts, towels, scarves, and cloth masks were tested…”

The conclusion is that the performance of improvised filters, such as scarves, overlaps surgical masks. Quoting

“Fabric materials may provide respiratory protection levels (i.e. total inward leakage) similar to the levels obtained using some surgical masks, which have been measured to be <10 (Oberg and Brosseau, 2008)…”

Individual virus particles are too small to be stopped. The authors have a theory complimentary to airflow modification.  They propose that like surgical masks, fabric improvisations are of benefit because much of the virus shed by an infected  individual is bound to larger particles.

Wear a scarf.

 

 

Leave a Reply

Your email address will not be published. Required fields are marked *