More U.S. hospitals are requiring masks and limiting visitors as health officials face a post-holiday spike in flu and other illnesses. New York City last week instituted a mask mandate for the city’s 11 public hospitals. Similar measures were ordered at some hospitals in Los Angeles and Massachusetts. Flu and COVID-19 infections have been increasing for weeks, with high levels of flu-like illness reported in 31 states just before Christmas. Updated national numbers are to be released Friday, but health officials predict infections will grow in many states well into January.