New Danish study reveals that wearing masks don’t stop the transmission of the coronavirus

A new Danish study out this morning has found no statistical difference in wearing masks versus not wearing masks when it comes to the transmission of the coronavirus:

NY TIMES – A new study, the first of its kind, is likely to inflame the controversy. Researchers in Denmark reported on Wednesday that surgical masks did not protect the wearers against infection with the coronavirus in a large randomized clinical trial.

The study, published in the Annals of Internal Medicine, did not contradict growing evidence that masks can prevent transmission of the virus from wearer to others. But the conclusion is at odds with the view that masks also protect the wearers — a position endorsed just last week by the Centers for Disease Control and Prevention.

How the study worked:

From early April to early June, researchers at the University of Copenhagen recruited 6,024 participants who had been tested beforehand to be sure they were not infected with the coronavirus.

Half were given surgical masks and told to wear them when leaving their homes; the others were told not to wear masks in public.

At that time, 2 percent of the Danish population was infected — a rate lower than that in many places in the United States and Europe today. Social distancing and frequent hand-washing were common, but masks were not.

About 4,860 participants completed the study. The researchers had hoped that masks would cut the infection rate by half among wearers. Instead, 42 people in the mask group, or 1.8 percent, got infected, compared with 53 in the unmasked group, or 2.1 percent. The difference was not statistically significant.

“Our study gives an indication of how much you gain from wearing a mask,” said Dr. Henning Bundgaard, lead author of the study and a cardiologist at the University of Copenhagen. “Not a lot.”

The downside to this study:

Critics were quick to note the study’s limitations. Among them: The incidence of infections in Denmark was lower than it is today in many places, meaning the effectiveness of masks for wearers may have been harder to detect. Participants reported their own test results; mask use was not independently verified, and users may not have worn them correctly.

As the NY Times points out, the CDC has cited other studies that do suggest the wearer is protected by a mask:

The study’s conclusion flies in the face of other research suggesting that masks do protect the wearer. In its recent bulletin, the C.D.C. cited a dozen studies finding that even cloth masks may help protect the wearer. Most of them were laboratory examinations of the particles blocked by materials of various types.

My own feeling about this whole ordeal is that wearing masks is a net positive when accompanied with other precautions. The one thing a mask can do is catch sputum when you sneeze which would be contaminated with the virus if you are infected. That doesn’t mean that coronavirus molecules are all stopped by the mask, because their size is often small enough to go through many masks that aren’t N95. But if you continually use a proper amount of hand sanitizer before removing your mask and touching or scratching your face when out in public (like at the grocery store), the risk of infection would logically seem to be much lower.

So I wear a mask when out in public and I use my little bottle of Germ-X before touching my face (if I don’t forget). So far so good. You can read the full Danish study here.

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