The answer: It depends on the study. So who are going to believe?

Date:   8/15/2021 4:01:33 PM ( 3 y ago)

Do masks actually work? The best studies suggest they don't
Kaylee McGhee White - Thursday
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Do masks actually work? The best studies suggest they don't
© Provided by Washington Examiner
Do masks actually work? The best studies suggest they don't

Over at City Journal, Jeffrey Anderson has written a very interesting article that dives into many of the studies our public health officials have used to justify mask-wearing. Now that the mask debate is back in full swing as several cities and states re-implement mask mandates, it’s worth asking, as Anderson does: How effective are masks really?

The answer: It depends on the study.

Anderson cites multiple medical studies on masking that fall into one of two categories: observational studies or randomized controlled trials, dubbed RCTs. He notes that much of the scientific community has based its masking guidance on observational studies rather than RCTs. (Note: Anderson is referencing cloth and surgical masks, not N95 respirators).

The Centers for Disease Control and Prevention, for example, released a press release highlighting an observational study that focused on two COVID-19-positive hairstylists in Missouri. Both stylists were showing symptoms but wore masks while serving 139 customers, most of whom were also masked. The result was that the 67 customers who subsequently chose to get tested for COVID-19 tested negative, and the 72 other customers reported showing no symptoms.

But as Anderson notes, there are several glaring problems with this study.
First and foremost, it did not have a control group.

Anderson writes:

Nobody has any idea how many people, if any, would have been infected had no masks been worn in the salon. Late last year, at a gym in Virginia in which people apparently did not wear masks most of the time, a trainer tested positive for the coronavirus. As CNN reported, the gym contacted everyone whom the trainer had coached before getting sick — 50 members in all — “but not one member developed symptoms."
Nobody has any idea how many people, if any, would have been infected had no masks been worn in the salon. Late last year, at a gym in Virginia in which people apparently did not wear masks most of the time, a trainer tested positive for the coronavirus. As CNN reported, the gym contacted everyone whom the trainer had coached before getting sick — 50 members in all — “but not one member developed symptoms."

This is why the trials are more reliable: They compare one variable group to a control group to determine just how effective the variable is. But besides the occasional brief mention, the CDC has not bothered to cite or mention any of the trials regarding masking. Why? Because, as Anderson says, “They don’t like what the RCTs show.”


He goes on to cite several trials conducted over the past several years, each of which found that cloth masks and surgical masks offer very little to no benefit at all. The one trial that specifically tested masks against COVID-19 was a 2020 study in Denmark with 4,800 participants. The researchers found that “1.8 percent of those in the mask group and 2.1 percent of those in the control group became infected with Covid-19 within a month, with this 0.3-point difference not being statistically significant,” Anderson writes.

Incredibly, the CDC has dismissed the Danish study as “inconclusive” and “too small” while praising the observational study of the Missouri hairdressers, with its fewer than 200 participants and no control group, as a landmark case, Anderson said.

Another trial Anderson mentions is a 2015 study that directly compared cloth masks to surgical masks. Its 1,100 participants, each of whom was a healthcare worker, were instructed to wear their masks at all times on every shift for four weeks. The study found that those who wore cloth masks were 13 times more likely to develop an influenza like illness than those who wore surgical masks. But even the surgical masks were found to be “poor” at preventing the penetration of particles, and cloth masks were “extremely poor.” Surgical masks let through 44% of particles. Cloth masks let through 97%.

Anderson concludes:

In sum, of the 14 RCTs that have tested the effectiveness of masks in preventing the transmission of respiratory viruses, three suggest, but do not provide any statistically significant evidence in intention-to-treat analysis, that masks might be useful.

The other eleven suggest that masks are either useless — whether compared with no masks or because they appear not to add to good hand hygiene alone — or actually counterproductive.

Of the three studies that provided statistically significant evidence in intention-to-treat analysis that was not contradicted within the same study, one found that the combination of surgical masks and hand hygiene was less effective than hand hygiene alone, one found that the combination of surgical masks and hand hygiene was less effective than nothing, and one found that cloth masks were less effective than surgical masks.
In sum, of the 14 RCTs that have tested the effectiveness of masks in preventing the transmission of respiratory viruses, three suggest, but do not provide any statistically significant evidence in intention-to-treat analysis, that masks might be useful. The other eleven suggest that masks are either useless — whether compared with no masks or because they appear not to add to good hand hygiene alone — or actually counterproductive. Of the three studies that provided statistically significant evidence in intention-to-treat analysis that was not contradicted within the same study, one found that the combination of surgical masks and hand hygiene was less effective than hand hygiene alone, one found that the combination of surgical masks and hand hygiene was less effective than nothing, and one found that cloth masks were less effective than surgical masks.

This is important because an honest conversation about masks requires taking a hard look at the scientific evidence backing them. And if Anderson is right and the CDC's observational studies are as sloppy and inconclusive as they appear to be, that's a problem. Millions of people have been led to believe that the only way they can protect themselves against this virus, besides getting vaccinated, is by strapping a piece of cloth around their noses and mouths. Social media giants and everyday busybody scolds have shamed and punished anyone who questions this guidance.

But the data cited by Anderson suggests that not only was this guidance wrong but that public health officials knew it was wrong and rolled it out anyway.

 

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