Although the term "tripledemic" sounds like something out of science fiction, it is a growing threat nationwide just as many employees are adjusting to returning to the office. As the name implies, the tripledemic refers to three respiratory viruses — RSV (respiratory syncytial virus), the flu and COVID – and it's threatening lives, as well return-to-work policies.

Infections have surged in several parts of the nation. Los Angeles County officials are considering reinstating an indoor mask mandate, including for shared office space and manufacturing settings, after COVID cases spiked recently. Case levels also are high in New York City. In Washington state, 25 hospital executives and 12 county health officers have asked residents to mask indoors. The Oregon Health Authority has asked people to protect children and older adults by wearing masks in crowded indoor spaces.

The U.S. Centers for Disease Control and Prevention advises that people living in areas with a high risk of COVID infection wear masks indoors. Right now, that's about 9% of U.S. counties. "To protect communities in those circumstances at those high levels, we have recommended and continue to recommend that those communities wear masks," CDC Director Dr. Rochelle Walensky told NPR News.