Australia is being crushed by something we’ve never seen before: an exponential increase in COVID-19 cases, even under lockdown and mask-wearing mandatory. But right under our noses – quite literally – we have a cheap, easy, and effective secret weapon in slowing the spread of the virus: better masks.

I recently returned to Australia from Silicon Valley. Almost 18 months ago, I realized that wearing a mask can help flatten the curve. That lightbulb moment inspired me to campaign for universally adopted mask wearing. I led a scientific team in April 2020 that wrote the first and largest evidence-based review of the effectiveness of masks against the spread of COVID-19. I published an opt-in washington articles and formed the #Masks4All movement that began to kick-start mask wearing in the United States and globally. Then there were no high-quality masks. So we focused our research on cloth masks that people can make themselves.

The way we wear masks can significantly affect their effectiveness.Credit:Wayne Taylor

Now, due to the increased transmittance of the Delta variant, last year’s masks are no longer up to the task. It’s time to start our game again.

Recent research has shown that simply wearing a closed cloth mask over your surgical mask, known as a “dual mask”, reduces exposure by more than 10 times compared to using only one. cloth or surgical mask.

A simple but equally effective change is to wear a surgical mask but knot and fasten the sides. This takes about a minute and can be done at home without tools.

Double masking and knotting both help seal the opening inside the surgical mask that otherwise allows virus particles to enter your lungs directly. COVID-19 is primarily transmitted by aerosolized respiratory particles that can be inhaled through air passing through adjacent openings. Bending the nose wire in your mask also gives a better seal.


Today, there are better, cheaper and more effective mask options on the market. For example, KF94 and P2 masks are the Korean and Australian standards, both of which provide a much better fit than surgical masks because they have no openings on the sides. The KF94 respirator is widely sold worldwide and has local P2 respirator production capacity. But it can be difficult for consumers to find them because very few companies import or manufacture them in Australia. It takes a major government or industry initiative to get an ample supply of better masks here and encourage people to use them.

But don’t wait for the government to roll out better masks. Visit to see an illustration of how to knot and fasten or double to make the mask you have now more effective.

Jeremy Howard is an Distinguished Research Scientist at the University of San Francisco and Co-Founder of and #Masks4All


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