Myocarditis and pericarditisThere is a link between COVID-19 vaccines and rare side effects of myocarditis and pericarditis.Myocarditis is inflammation of the heart muscle.Pericarditis is inflammation of the pericardium (the thin, sac-like tissue surrounding the heart muscle).Myocarditis and pericarditis can occur together or separately. Myocarditis and pericarditis occur in the general population from a variety of causes. Not all cases that occur after vaccination are caused by the vaccine. Myocarditis and pericarditis can also be caused by COVID-19.The risk of myocarditis is highest in people aged 16 to 30 years (peak 16 to 18 years), and is higher in males than females.1-3 The risk does not appear to be as high with booster doses compared with dose 2 of the primary course.3,4Up-to-date information on cases and rates reported to the Therapeutic Goods Administration (TGA) is available in its COVID-19 vaccine safety reports. The risk of myocarditis is higher (although still rare) after vaccination with Moderna original formulation compared with Pfizer original formulation. It is estimated there are around 2 more cases per 100,000 second vaccine doses in people under 40 who received Moderna original formulation than Pfizer original formulation.Evidence suggests that AstraZeneca and Novavax are probably associated with a small increased risk of myocarditis and pericarditis.This risk after AstraZeneca looked lower than the risk after Moderna original formulation or Pfizer original formulation. The small number of total doses of Novavax given globally prevents the calculation of a precise risk as of February 2023.ATAGI will continue to monitor data as it emerges and update advice accordingly.There is no evidence to suggest myocarditis or pericarditis is more severe following a particular brand of vaccine.
