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May 2022

Masks Redux

"You’ve got to be very careful if you don’t know where you are going, because you might not get there."

—Yogi Berra

As cases of COVID-19 ascend in areas of the US, some schools are reverting to requiring masks. Of course this is accompanied by renewed claims that they are ineffective. In fact, Florida governor Ron DeSantis issued an executive order barring local school districts from requiring their students to wear masks, claiming that there was no evidence that masks prevent infection in schools. That claim has been levied over and over by many politicians, talking heads, pundits, and assorted Facebook “experts.” But, they are flat wrong. There are multiple lines of evidence from a variety of disciplines—including materials science, infectious diseases, pediatrics and epidemiology—showing that masks can help protect children and teachers from getting COVID in schools. Some of that evidence has already been presented in these pages, and I now add to that body of evidence, more  data recently summarized in Scientific American.

  1. For starters, laboratory experiments show that masks block the respiratory droplets and aerosols that transmit SARS-CoV-2, the virus that causes COVID. In one test, an engineering team at the University of Wisconsin–Madison used a machine in a classroom setting to pump out particles the same size as those that carry the virus from an infected person. The researchers placed several CPR dummies with or without masks around the room and measured the degree to which the aerosols penetrated the masks. They reported that a surgical mask reduced the chances of penetration by 382 times when compared to the maskless mannequins.
  2. Then, in the real world, not a laboratory setting, several epidemiological studies also concluded that masks in schools work. Researchers at the ABC Science Collaborative in North Carolina collected data from more than a million K–12 students and staff members from schools across that state, which mandated masking in schools from August 2020 until July 2021. The scientists reported little in-school transmission when the mask mandates were in place during the fall, winter or summer months. During this time, in-school transmission remained low as COVID cases fluctuated outside the schools. With mask mandates, rates of within-school spread were as low as one percent.
  3. Masks, combined with other prevention efforts, also reduce the risk that students might bring home the virus to parents or other relatives. An online survey of 2.1 million Americans by researchers at Johns Hopkins University showed a 38 percent increased risk of COVID-related illness in households with a child attending school in person. That risk went down, however, as the number of school-based mitigation measures, including mask mandates went up.
  4. Studies done in wider communities beyond schools give the strongest real-world evidence that masks stop COVID’s spread. An international team of researchers conducted a randomized controlled trial involving nearly 350,000 people across 600 villages in rural Bangladesh. Half of the villages got free cloth or surgical masks and a promotional campaign encouraging their use. The other half did not. The researchers found that the mask intervention significantly curbed coronavirus transmission.

Bottom line:  The effectiveness of masks in schools is supported by many different studies and analyses that show similar results. There are more than a dozen studies beyond those cited here, that all point to the same conclusion:

Masks work.

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What Happened To The Flu And Other Respiratory Diseases?

A NYC based travel blogger who travels a lot used to get a respiratory infection whenever she flew. That stopped when the airline mask mandates went into effect. The mandates, of course, were designed to hinder the spread of the CoV-2 virus that causes COVID, but it makes sense that if masks and other physical (that is, non-medical) mandates worked to mitigate COVID, then we would see a decrease in other contagious respiratory diseases after the mandates were, well…mandated.

We did.

The mandates worked, despite persistent claims of some to the contrary. This particular blog subject was stimulated by a radio talk show where a couple of nonscientist talking heads announced that there was no scientific proof that the masks or other mandates prevented disease. I previously posted in these pages evidence that masks, in particular, do indeed work to retard the spread of disease (see here, here, here, and here). In this post, I present further data on how the mandates significantly reduced the incidence of other infectious respiratory diseases around the world. If the measures can reduce flu, then you can bet that they also reduced COVID-19.

Note, however, that this is not necessarily an endorsement for returning to the measures. Your humble scribe didn’t much like his glasses fogging up, or having to make two trips from the car to the store because he forgot his mask. But, let’s argue the issue based on its merits and not from false premises based on incorrect claims.

After South Korea implemented various hygiene and social distancing measures in response to COVID, they saw the 2019-20 flu season end an astounding 12 weeks earlier than the previous year. Epidemiological surveillance data bolstered by clinical diagnostic testing showed that infection from several different pathogenic respiratory viruses (including adenovirus, bocavirus, metapneumovirus, rhinovirus, flu, parainfluenza, and respiratory syncytial virus) dropped to nearly 0% just five weeks into 2020!

In the United States, the incidence of infection by influenza, respiratory adenovirus, rhinovirus, enterovirus, RSV, non-COVID coronaviruses, metapneumovirus, and parainfluenza viruses all decreased in March 2020, soon after implementation of mandates. Similar results were seen in Japan.

More dramatically, since pandemic mitigation measures were put in place, there has been a 99% global reduction of infections from both influenza types A and B compared to prior years. In particular, one of two flu B substrains has not been isolated in the world since August 2021 suggesting that this variant is now extinct. The overall genetic diversity of influenza viruses has also dramatically diminished indicating that other flu sub-types (or clades) have disappeared around the world since the pandemic mandates were put in place.

And this reduction of respiratory infectious disease does not only hold for those caused by viruses. Another study looked at surveillance data from 26 countries across 6 continents for several bacterial diseases caused by Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitidis, which are typically transmitted via respiratory droplets. Numbers of weekly cases in 2020 were compared with corresponding data for 2018 and 2019. Data for disease due to Streptococcus agalactiae, a non-respiratory pathogen, were also collected from nine laboratories for comparison. All countries experienced a significant and sustained reduction in respiratory bacterial diseases in early 2020 (Jan 1 to May 31), coinciding with the introduction of non-medical COVID containment measures in each country. By contrast, the incidence of disease due to S agalactiae (which is not transmitted by the respiratory route) did not differ significantly from the 2 previous years.

Clearly, the mandates significantly reduced the incidence of respiratory infections by non-COVID viruses and bacteria. They worked. So, why did we still have COVID infections after the mandates went into place? The mandates reduced, not eliminated these diseases, so infections still happened. Since we did not have historical COVID infection data from previous years to compare with, the effects of the current mandates on the incidence of COVID are not as clear cut as they are with other diseases for which we do have historical data for comparison. But, as I wrote before (see above), it is clear that places in the US and around the world that used masks and other protective measures saw reduced incidence of COVID compared to similar places that did not.

Bottom line: The studies mentioned here regarding non-COVID infectious diseases fully support data previously posted in these pages that the mandates, including masks, are effective non-medical tools for controlling infectious respiratory diseases.

Don’t let anyone tell you differently.