Q&A – Mask “Efficacy”

Today’s entry: Hi Brian, Where are the studies that prove wearing a cloth face covering "mask" reduces your chance of contracting the COVID virus, or any flu-type airborne virus for that matter? They should include data with % reductions based on age groups, data that shows the difference between inside and outside mask use. Before I wear anything covering my face or encourage anyone to do so I want to know specifically why? Currently, the vast majority of people believe wearing a cloth mask protects them and those around them from the virus, but what scientific data is this based on? If the premise is incorrect, that masks significantly reduce your chances of contracting COVID then wearing a mask is nonsensical.  

Bottom Line: The kind words are appreciated as is your willingness to accept my pragmatism. You’re also right regarding my personal stance on masks and the reason is another of my sayings. It’s been a long time, in fact nearly a year, since I’ve covered accredited studies of mask efficacy. Those types of studies have and do exist.

The first related studies were released in April of last year and a smattering of related studies have occurred over the past year as well. Now’s a good time because just recently an accredited mask study testing against the variants was completed and recognized by the CDC. In total there are ten studies recognized by the CDC and posted to their website. I’m going to focus on two which most specifically address your question regarding the effectiveness of cloth masks, in addition to N95 masks.

The first is a study published in the medical journal the Lancet early in the pandemic last year. It found that the use of masks reduces the spread of COVID-19 by an average of 85%. Furthermore, social distancing by as little as three feet reduces spread by 77% and the use of masks in public is equally effective as compared to the medical staff at hospitals. Also, N95 masks are 96% effective, and basic masks are 77% effective.

The “basic” masks in the study are cloth masks. Clearly, they weren’t nearly as effective as the best available masks, however, they were still effective against the original strain a little more than three-quarters of the time when studied. A lot has changed in a year. Including the pervasiveness of the spread of the virus. 

Did you, did anyone, suspect we’d be battling a bigger outbreak of new COVID-19 cases today compared to a year ago? With well over half of the population vaccinated that’s certainly not what we were conditioned to expect. This is a reminder as to why it’s so important to establish and study facts as opposed to simply listening to the “experts”. If all you did was listen to the “experts” you’d likely be a six-masked unemployed hermit who’d still have contracted COVID-19 twice. One of the changes over the past year has come in the form of overall mask “efficacy”.

The more contagious COVID-19 variants have a greater emphasis on the study of fine droplets. I couldn’t find a disparity in the N95 data compared to the original virus, which speaks to the overall effectiveness of that mask specifically. When it comes to cloth masks, however, there’s been a meaningful decline in performance. A CDC study said, "Multi-layer cloth masks can both block up to 50-70% of these fine droplets and particles". In other words, the best possible performance of cloth masks is currently 7% worse than the average performance of cloth masks a year ago. The average performance is 17% worse and you might have noticed another detail. That’s the performance of multilayer cloth masks. There’s no current accredited data on single-layer cloth masks against the variants but it’s safe to say their performance would be well south of 50% at best. And this is where I think it’s useful to tie some things together. 

Each day I feature a listener question sent by one of these methods. 


Parler & Twitter:@brianmuddradio 

The Coronavirus Crisis In Germany: Week 7

Photo: Getty Images Europe

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