First, health officials said we shouldn't wear face masks. Then, they said we should. Now, many are saying we must wear masks if we want to keep the economy open and save tens of thousands of lives.
The Centers for Disease Control and Prevention now says everyone "should wear a cloth face cover when they have to go out in public, for example to the grocery store or to pick up other necessities."
The best way to reduce Covid-19 transmission is by wearing a face mask, study finds
"Cloth face coverings are meant to protect other people in case the wearer is unknowingly infected but does not have symptoms," the CDC said.
But the benefits go both ways. "We know now there's scientific evidence that masks both keep you from infecting others but may also partially protect you from getting infected," said Dr. Deborah Birx, the White House coronavirus task force coordinator. "I think that's a new discovery and a new finding."
If 95% of Americans wore face masks in public, it could prevent 33,000 deaths by October 1, according to the University of Washington's Institute for Health Metrics and Evaluation.
So why has the guidance on face masks changed since the pandemic started? This novel coronavirus is still just months old, and scientists are constantly learning more about it -- including more reasons why wearing masks is so important:
-- It's easy to spread this virus by just talking or breathing.
-- This coronavirus is highly contagious. Without mitigation efforts like stay-at-home orders, each person with the coronavirus infects, on average, another two to three other people. That makes it twice as contagious as the flu.
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-- It's easy to spread the coronavirus without any symptoms -- either from asymptomatic carriers or pre-symptomatic carriers.
-- This virus has a long incubation period -- up to 14 days -- giving a wide window of opportunity for people to infect others before they even know they're infected.
-- Carriers may be most contagious in the 48 hours before they get symptoms, making transmission even more blind.
In other words, it's not just people who are sneezing and coughing who can spread coronavirus. It's often people who look completely normal and don't have a fever. And that could include you.