A: Signs point to YES!
As we’ve been heard to say, “absence of evidence is not evidence of absence.” While our gold standard randomized controlled trials are not very practical for testing the efficacy of masks during a pandemic (how would YOU like to be in that placebo group?!), accumulating evidence from different types of studies has strengthened the case for face masks as an important part of our COVID-19 prevention toolkit.
Today, 2 exciting new pieces of evidence:
*1) In Springfield, Missouri, two hairstylists with COVID-19, wearing double-layer cotton masks or surgical masks, did NOT pass it on to any of their 139 clients who were also masked.
*2) In the largest health care system in Massachusetts, universal masking for both health care workers (HCWs) & patients was associated with a steady decline in HCWs with positive tests for SARS-CoV-2.
Neither of these studies is perfect; the hairstylist study is an example of a “case study” (as opposed to a large sample of COVID-19 + hairstylists) so these results could still have been due to random good luck or other protective factors not measured.
In the health care worker study, other preventive measures such as distancing likely changed in conjunction with universal masking, but the daily number of SARS-CoV-2 infections in the community was continuing to increase or plateau during this time, suggesting risk of exposure should have remained at least constant.
So despite not being randomized, these two studies add real-world evidence that supports the “precautionary principle” to recommend face masks, especially in situations where close contact cannot be avoided.
This has led the CDC to finally call for “Universal Masking to Prevent SARS-CoV-2 Transmission—The Time Is Now”
The Nerdy Girls agree! #MaskUp #StaySMART
