The Importance of Masks: Small actions with big results


Did you know that a family of mice can multiply to over 100,000 mice in a single year? Now: Imagine if the first two mice never met. That’s a difference of 99,998 mice.

Covid-19 can work like this, too. Preventing a single new infection can make a huge difference over time.

One thing we’ve learned is that mask use seriously reduces transmission rates, perhaps by as much as 50-75 percent. And if that’s the difference between ten infected people transmitting the virus to 14 others, or just seven; it means a lot.

Even though models and estimates are essentially “educated guesses,” that guess is based on a growing amount of research. Now that we can look back at what has happened over the last three months, there is good reason to believe the models are on track. An estimate from the Institute for Health Metrics and Evaluation predicts that wearing masks is 50 percent effective, or in other words, will prevent half of the new infections. If masks can block 50 percent of new infections, and 95 percent of people wear them for the next three months, this would reduce the state’s estimated daily infection rate on October 1 to less than 250 new cases.

Without masks? Then the model predicts that we’ll see 2,400 new cases on that day. Yes, 2,400 cases in just a single day. And the deaths will increase too, from a single death (if masks are worn) to 11 deaths that day (if masks are not worn).

A local model, developed in Whatcom County, used a different estimate to explore the impact of wearing masks. This model assumes a 75 percent effective rate for masks (masks prevent three out of four new infections) and uses information about social distancing and observed mask-wearing behaviors at local shopping centers. The study estimated that about 46 percent of Whatcom County shoppers were wearing masks in early June, and explored what would happen if that number increased to 80 percent.

It turns out, that would make a big difference. For Whatcom County, the new daily cases estimated for October 1 would be just five if masks were worn by 80 percent of the population. If we continue with 46 percent use rates though, the predicted new daily case count is more than 1,900.

Wearing a mask when you’re in public is an easy way to show that you care about your community and that you want to speed up our economic recovery from Covid-19. Whether mask use is 50 percent, 75 percent or even just 25 percent effective, the outcomes three months from now will be very different based on our actions today and tomorrow. The good news is that we can all play a part in putting Covid-19 behind us and that the solution could very well be right in front of our faces. We’re all in this together.

Learn more at the Whatcom County Health Department’s website,


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