The number of cases of a heart inflammation condition in 16-to-24-year-olds was higher than expected after they received their second dose of Pfizer or Moderna’s Covid-19 vaccines, the Centers for Disease Control and Prevention said Thursday, citing preliminary data from its vaccine safety monitor system. There have been 275 reported cases of myocarditis or pericarditis, which are inflammation conditions involving the heart, in people ages 16 to 24 as of May 31, according to a CDC presentation that was prepared for a Food and Drug Administration advisory panel meeting Thursday.