A new paper, published today in leading scientific journal Nature and authored by an international team of researchers, found that "surgical face masks could prevent transmission of human coronaviruses and influenza viruses from symptomatic individuals."
The use of face masks to keep the ongoing coronavirus pandemic in check has been extremely controversial among public health researchers. At first, particularly in the US, officials were slow to recommend them, advising the public to keep existing stocks of surgical masks and N95 respirators available for healthcare workers.
Now, though, the US Centers for Disease Control (CDC) is expected to soon advise all Americans to wear cloth masks in public.
But there's no clear message coming from the White House. Trump officials still seemed hesitant as recently as a Thursday evening briefing.
The new paper, however makes a compelling argument supporting the CDC's thinking.
The question hinges on how coronaviruses and influenza viruses actually spread.
Common cold symptoms from respiratory virus infections, caused by coronavirus and influenza viruses, lead to human to human spread through a variety of pathways: direct or indirect contact, respiratory droplets, and finer particles called aerosols.
The Nature study largely focused on spread through droplets and aerosolized particles to test for the efficacy of surgical face masks.
The researchers argue that little is actually known about the effectiveness of surgical masks since "most of the existing evidence on the filtering efficacy of face masks and respirators comes from in vitro experiments with nonbiological particles" and that "most research has focused on influenza" — not SARS-Cov-2.
So how can we generalize what we already know to the current COVID-19 pandemic?
In a trial using a breath-capturing device called the "Gesundheit II machine," they found that the coronavirus was detected in 30 and 40 percent of droplets and aerosols expelled by people not wearing a mask. Strikingly, though, the coronavirus was not detected at all from participants wearing face masks, neither through droplets or aerosols.
The results, while striking, should still be taken with a grain of salt.
"In normal times we'd say that if it wasn't shown statistically significant or the effective in real-world studies, we don't recommend [wearing masks]," Don Milton, senior author of the Nature study and professor of applied environmental health at the University of Maryland, told Science Daily.
"But in the middle of a pandemic, we're desperate," Milton added. "The thinking is that even if it cuts down transmission a little bit, it's worth trying."
At the same time, supplies of masks are dwindling. Healthcare workers across the Western world are having to adapt, choosing to wear DIY cloth masks fabricated by a "sewing army," reminiscent of World War II ammunitions manufacturing.
An impending recommendation by the CDC to wear surgical masks could end up highlighting the current issues plaguing the global supply and demand of masks — a war that is only getting started.
The Trump administration reportedly asked medical supply firm 3M to stop selling N95 respirators to Canada — likely a desperate move to keep masks in the country. The US also allegedly hijacked an entire plane shipment of masks that was initially destined for France.
Getting an effective mask into the hands of every American will likely take time. For the time being — and considering the latest research available to us — it's perhaps best to cover up when outdoors, whether that's a scarf, a cloth mask, or a fully fledged N95-certified respirator.
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READ MORE: Respiratory virus shedding in exhaled breath and efficacy of face masks [Nature]
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