In June 2021, health officials declared a “likely association” between receiving the second dose of the Moderna or Pfizer-BioNTech vaccines and developing myocarditis or pericarditis, specifically in young men under 30 years old. Occurrences of both conditions seem to be rare side effects, “about a dozen reports … per million shots of the second dose among people 12 to 39 years old, with higher rates among younger men in those age groups.” While this is an extremely low percentage, domestic and international health officials believe this side effect worth noting and the FDA proceeded to update the fact sheets for both vaccines and release them June 25, 2021.
Myocarditis is inflammation of the heart muscle. It can reduce the heart’s ability to pump and causes rapid, abnormal heartbeats known as arrhythmias. Other common symptoms include chest pain, fatigue, and shortness of breath. Severe cases can weaken the muscle to the point where blood clots form, which could lead stroke or heart attack. Pericarditis is the “swelling and irritation of the thin, saclike tissue surrounding the heart.” This most commonly causes sharp chest pain but can also lead to abdominal or leg swelling, cough, fatigue, low-grade fever, pounding or racing heartbeat, and shortness of breath. Both conditions can have different causes but are notably caused by viral infections. Also, if mild, both conditions can resolve without medical intervention. Those with confirmed cases following a vaccine dose were hospitalized but most did not require any serious intervention and were discharged.
Covid-19 vaccines are still recommended for those 12 years and older, and “Sara Oliver of the CDC’s National Center for Immunization and Respiratory Diseases reiterated that even with the risk of myocarditis, ‘the benefits still clearly outweigh the risks for Covid-19 vaccination in adolescents and young adults.’” The data provided by federal health agencies suggests the vaccine has proven to decrease the rate of infection and transmission in parts of the country with high vaccination numbers. Health officials will continue to monitor side effects of the vaccine and update documentation where applicable.