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Universal Masking Reduces Severity of Infection by reducing inoculum: masks really work.


This article appeared in the Journal of General Internal Medicine online July 31, 2020: “Masks Do More Than Protect Others During COVID-19: Reducing the Inoculum of SARS-CoV-2 to Protect the Wearer.” As promised by the title, it details the concept of reducing exposure to the virus by wearing a mask. It explains that a lower dose of infectious virus will lead to a milder infection. This phenomenon was shown by a natural experiment, conducted on two separate cruise ships infiltrated by the virus early in the pandemic:

Closed settings, such as cruise ships, can be particularly illustrative when examining phenotypes associated with SARS-CoV-2. For example, one of the earliest estimates of the rate of asymptomatic infection due to SARS-CoV-2 was in the 20% range from a report of a COVID-19 outbreak on the Diamond Princess cruise ship.37 In a more recent report from a different cruise ship outbreak, all passengers were issued surgical masks and all staff provided N95 masks after the initial case of COVID-19 on the ship was detected.38 In this closed setting with masking, where 128 of 217 passengers and staff eventually tested positive for SARS-CoV-2 via RT-PCR, the majority of infected patients on the ship (81%) remained asymptomatic,38 compared with 18% in the cruise ship outbreak without masking.37

The article goes on to cite the examples of Taiwan, Japan, Singapore, Hong Kong, and other countries that have embraced universal mask-wearing and have fared relatively much better in case and fatality rates than countries like the United States, where mask-wearing has been inconsistent and politically polarized.

Finally, this is the lede to a Wall Street Journal article dated December 30, 2020:

NEW DELHI—In September, India was reporting almost 100,000 Covid-19 cases a day, with many predicting it would soon pass the U.S. in overall cases. Instead, its infections dropped and are now at one-fourth that level.

India has brought down its virus numbers, despite often being too crowded for social distancing, having too many cases for effective contact tracing and an economy that isn’t well equipped to weather long lockdowns.

One of the main reasons, Indian health officials say, is that the country has managed to encourage and enforce almost universal acceptance of masks without much debate.

From the moment the pandemic landed in this South Asian nation, politicians and health experts have been united about the importance of masks, including Prime Minister Narendra Modi.

(from Wall Street Journal “teaser page” for article)

Need I say more? Even the Wall Street Journal agrees that masks work. I plead with you to wear a mask in public, even after vaccines become available, regardless of your political affiliation.

(SARS-COV-2 Electron Micrograph: photo courtesy NIAID)

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