Florida Surgeon General Joseph Ladapo ignited a furor this month when, based on a state analysis purporting to show COVID-19 vaccines were linked to cardiac deaths in young men, he advised men ages 18 to 39 to steer clear of the shots. Scientists slammed his warning and decried the eight-page analysis, which was anonymous and not peer reviewed, for its lack of transparency and flawed statistics.
Still, COVID-19 vaccines do have a rare but worrisome cardiac side effect. Myocarditis, an inflammation of the heart muscle that can cause chest pain and shortness of breath, has disproportionately struck older boys and young men who received the shots. Only one out of several thousand in those age groups is affected, and most quickly feel better.
A tiny number of deaths have been tentatively linked to vaccine myocarditis around the world. But several new studies suggest the heart muscle can take months to heal, and some scientists worry about what this means for patients long term. The U.S. Food and Drug Administration (FDA) has ordered vaccinemakers Pfizer and Moderna to conduct a raft of studies to assess these risks.