Some hospitals across the United States are reinstating indoor masking rules amid rising cases and hospitalizations of respiratory illnesses including COVID-19 and influenza.

Hospitals in at least six states — California, Illinois, Massachusetts, North Carolina, Washington and Wisconsin — have put masking guidelines in place, according to an ABC News count.

Over the weekend, Mass General Brigham, which is the largest health system in Massachusetts, told ABC News it issued guidelines requiring employee caregivers and those working in patient care areas to wear masks.