“Everything changes and nothing stands still,” wrote the classical Greek philosopher Heraclitus, around the time that Hippocrates forged the meaning of epidemic. In the time of COVID-19, a rapidly evolving global pandemic has required a rapidly evolving response.
That brings us to the latest recommendation about double masking. During the early COVID-19 disease transmission in the US, CDC recommended against masks given insufficient evidence. This changed by May 2020, as increasing evidence supported masks as effective protection. Since then, the evidence has been overwhelming that masking dramatically reduces the transmission and impact of the novel coronavirus.
All masking is not the same. Studies have shown that some masks are better than others. Adding more layers to decrease transmission risk seems intuitive. Studies are starting to support this. Dr. Anthony Fauci, chief medical adviser on COVID-19 to the White House, has endorsed double masking as a sensible approach to increase protection. Specifically, a group studying masks has recommended wearing a well-fitted cloth mask over a surgical mask, creating additive filtration layers as well as a snug fit.
This double masking can produce 70-90% efficiency for preventing transmission of COVID-19. This is closer to the efficiency of an N95, which continue to be in very short supply. In comparison, a surgical or cloth mask by itself can produce ~50% efficiency.
Thinking about effective masking comes in the wake of multiple deadly regional surges that have dangerously taxed healthcare infrastructures, such as in Los Angeles and Arizona. Coronavirus mutations have also produced multiple variants that are spreading more efficiently from person to person.
Highly effective COVID-19 vaccines are now getting into the arms of millions of people, but getting to herd immunity will take several months. Additionally, the vaccines prevent disease, but we do not know yet how well they prevent transmission. Masks will be necessary for some time. Although the fundamentals of public health—social distancing, masking, and hand hygiene—have not changed, simple ways that can increase effectiveness are much needed. Double masking provides accessible additional protection.
The downside is that there is an inverse relationship between mask effectiveness and “breathability.” Double masking will not be feasible or comfortable for all people at all times. This may be especially the case in warmer weather.
Double masking can be considered an additional tool—it can be done all the time if possible or reserved for specific high-risk exposures. During a surge or in higher risk situations like public transportation, the double mask can provide an additional layer of protection. Although each tool (masking, distancing, hand washing) is imperfect on its own, combined, the protection can be significant.
Heraclitus also wrote, “It is disease that makes health sweet.” Although we have already been on a long road in this pandemic and still have a distance to go, we have robust, scientifically informed tools, including double masking, that light the way out, when we can again breathe freely.
Dharushana Muthulingam, MD, MS is an infectious disease physician and public health researcher in St. Louis, MO