Over 1,200 cases of post-vaccination heart inflammation have been reported to health authorities in the United States, according to slides set to be presented during a meeting on Wednesday. The bulk of the reports submitted to the Vaccine Adverse Event Reporting System, a passive reporting system run by two top health agencies, dealt with myocarditis or pericarditis experienced after a second dose of a messenger RNA-based COVID-19 vaccine. Of the 1,226 reports of post-vaccination heart inflammation—a jump from under 800—827 were for myocarditis or pericarditis after dose 2. Another 267 were after dose 1. The rest were reports after an unknown dose. Most of the cases were seen after the Pfizer-BioNTech shot. The others were seen after a Moderna jab. Continuing a trend first seen earlier this year, the majority of the patients were male. About 40 percent were seen in persons 29 years old or younger. Of the 323 cases meeting …