Following reports earlier this month of rare but higher-than-expected cases of heart inflammation in teens and young adults who got two shots of an mRNA Covid vaccine, a CDC expert group is meeting today to discuss the vaccines' safety profile. CDC and FDA officials previously reported preliminary data: There were 573 cases of myocarditis and pericarditis after the second shot of either mRNA vaccine currently available, but only 216 such cases after the first dose. Experts will also evaluate data on additional Covid-19 booster shots to fend off the virus.