The guidance on masks appears to be shifting, but social distancing is still the key step people can take.

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Thomas Perls, Boston University
As a professor at Boston University?s School of Medicine and a geriatrician at Boston Medical Center caring for the most vulnerable in this pandemic, I?ve been asked a lot of questions about COVID-19.
It turns out there is good science out there that helps us know what masks we need to wear and when to wear them. That being said, some of the following advice could change as scientists learn more about why some people get a bad or even lethal case of this virus while many more get through it OK. One of the areas of greatest confusion seems to be about masks.
Much of the decision about wearing masks depends on what the essential businesses that remain open are doing to ensure social distancing and therefore, our safety. Knowledge will protect you
Guidance about wearing a mask has to do with the different ways viruses like COVID-19 spread from person to person: through contact, droplets and as airborne, also called aerosolized, particles.
People get infected with COVID-19 when they touch a contaminated surface like a subway handle, or shake hands and then touch their face. Steel and plastic surfaces can harbor live virus for three days. On average, people touch their faces every two-and-a-half minutes, so it is easy to see how this virus can spread so easily from one person to the next by touching surfa...