US drug regulators on Friday added a warning to the literature that accompanies Pfizer/BioNTech and Moderna COVID vaccine shots to indicate the rare risk of heart inflammation after its use. For each vaccine, the fact sheets for healthcare providers have been revised to include a warning that suggest increased risks of myocarditis and pericarditis, particularly after the second dose and with onset of symptoms within a few days after vaccination, the FDA said. As of June 11, more than 1,200 cases of myocarditis or pericarditis have been reported to the U.S. Vaccine Adverse Event Reporting System (VAERS), out of about 300 million mRNA vaccine doses are administered. The cases appear to be notably higher in males and in the week after the second vaccine dose. 309 hospitalizations from heart inflammation in persons under the age of 30 have been reported, of which 295 have been discharged, according to the CDC. The latest update from FDA follows an extensive review of information and the discussion by CDC’s Advisory Committee at the Immunization Practices meeting. Pfizer and Moderna did not immediately respond to requests for comment after business hours.