Philadelphia Phillies minor league pitcher Corey Phelan dies of cancer at age of 20

Confirmed COVID-19 cases have risen more than 50% in 10 days, the threshold at which the city's guidelines call for people to wear masks indoors, said Dr. Cheryl Bettigole, the health commissioner. Health officials believe the recent spike is being driven by the highly transmissible BA.2 subvariant of omicron, which has spread rapidly throughout Europe and Asia, and has become dominant in the U.S. in recent weeks.

``If we fail to act now, knowing that every previous wave of infections has been followed by a wave of hospitalizations, and then a wave of deaths, it will be too late for many of our residents,'' said Bettigole, noting about 750 Philadelphia residents died in the wintertime omicron outbreak. ``This is our chance to get ahead of the pandemic, to put our masks on until we have more information about the severity of this new variant.''

Health inspectors will begin enforcing the mask mandate at city businesses on April 18.

Most states and cities dropped their masking requirements in February and early March following new guidelines from the U.S. Centers for Disease Control and Prevention that put less focus on case counts and more on hospital capacity. The CDC said at that time that with the virus in retreat, most Americans could safely take off their masks.

Philadelphia ended its indoor mask mandate March 2, and Bettigole acknowledged ``it was wonderful to feel that sense of normalcy again.''

Confirmed cases have since risen to more than 140 per day _ still a fraction of what Philadelphia saw at the height of the omicron surge _ while hospitalizations remain low at only 46 patients.