EDITOR:

Ralph Blasier’s letter on 11/30 discussed ‘the first randomized clinical trial’ of medical vs cloth masks on respiratory or influenza infection in health care workers (HCWs), but gave no article citation so readers could check it out for themselves. The study, funded by 3M – that manufactures masks- was done in Vietnamese hospitals in 2011. The only statistically significant finding was that HCWs who wore cloth masks had a higher relative risk for influenza-like illness than medical masks wearers (http://dx.doi.org/10.1136/bmjopen-2014-006577). Over 4 weeks, 29 of 580 (5%) of medical mask and 56 of 569 (9.8%) cloth mask wearers had a respiratory or influenza infection (not 2.5-13 times risk, per Dr. Blasier). Question: is that difference clinically significant? We have no information about infection rates in patients, HCW families or communities during the study, and or if masks used were equal to those now used in the US. Blasier’s conclusion: “most people are wearing masks that have no actual effect”.

Brian Black’s response restated CDC SarsCoV2 mitigation recommendations – vaccinations, masks, and social distancing. Thanks to Republican state legislators – neither physicians nor public health experts – the state cannot can’t mandate masks (or vaccinations). Charlatans continue to spread disinformation. Michigan (and, in the UP, Delta County) have among the highest rates of new cases and deaths, and hospitals are hamstrung by unvaccinated Covid-19 patients, who account for 90% of Covid deaths.

If you’re not sure who or what to believe, check out Google Scholar (rather than Facebook, Twitter, or Tucker Carlson) to can find articles peer-reviewed for accuracy. Even abstracts provide more trustworthy information than some crackpot ideas continuing to spread. Entering ‘Covid-19 masks study’ resulted in numerous titles including:

– COVID-19: mask efficacy is dependent on fabric and fit (doi: fmb-2020-0292). COVID-19 reproduction rate is linearly related to face mask efficacy AND the proportion of people wearing masks. Small changes in either result in large changes in Covid rates. Mask’s greatest benefit is protecting others from the mask wearer.

– Evaluation of cloth masks and modified procedure masks for the public during the COVID-19 pandemic (doi:10.1001/jamainternmed.2020.8168). Tested filtering efficacy of consumer-grade and standard medical masks, and ways to increase effectiveness. Some consumer masks were better than medical masks. N-95s are superior to either.

– Face masks to prevent transmission of COVID-19: a systematic review and meta-analysis (doi.org/10.1016/j.ajic.2020.12.007). Only six case-control studies met meta-analysis inclusion criteria, limiting the confidence for definitive conclusions, but mask wearing is effective in preventing COVID-19 spread (OR = 0.38, 95% CI: 0.21-0.69).

I think Dr. Blaiser overstated his case that mask wearing is futile. Masks are one leg of the stool protecting us from this information-age pandemic, and most people are not wearing them continuously for 4 hours. Remember, the least effective face mask is the one not worn, or one that doesn’t cover the mouth and nose. Look around: masks are uncommon in Delta County.

Rita Wickham

Rapid River