Getting at least one dose of the Pfizer vaccine increased the risk of a rare type of heart inflammation, especially in young males, according to a large new study from researchers in Israel. However, the diagnosed cases were usually mild, and most of the patients were sent home without ongoing need for treatment.

The condition, called myocarditis, an inflammation of the heart muscle, has been reported in a very small number of people who received either the Pfizer-BioNTech or the Moderna mRNA vaccines. Symptoms can include chest pain, palpitations and shortness of breath. Most patients who get care recover quickly.