A recent editorial in the New England Journal of Medicine called asymptomatic transmission of this coronavirus “the Achilles’ heel of COVID-19 pandemic control.”

A study in the same journal found rapid transmission of the virus in a skilled nursing facility in Washington state. More than half of residents with positive test results were asymptomatic at the time of testing and most likely contributed to spread of the disease.

Experts estimate anywhere from 25 to 50 percent of COVID-19 patients aren’t even aware they have it because they have no symptoms. But those people can easily spread this virus to others. It’s possibly one of the biggest reasons COVID-19 spreads faster than the SARS  virus did back in 2003 and the influenza virus does every year.

Expect more calls to screen everyone who works in crowded places or with vulnerable people, like nursing homes, prisons, homeless shelters and hospitals.

And it suggests it’s still reasonable to wear a mask in crowded outdoor or indoor spaces.