The CDC is investigating reports of young COVID-19 vaccine recipients who experienced heart inflammation.

The government health agency said it has received word that a small number of predominantly male adolescents and young adults developed myocarditis, an inflammation of the heart muscle.

The condition can be caused by a number of viruses, and often goes away without complications, the Advisory Committee on Immunization Practices said.

Officials were not alarmed by the cases but said healthcare workers should be aware of the “potential adverse event,” in a May 17 statement.

The group did not specify the number of people affected but said cases usually occurred within four days of taking the Moderna or Pfizer/BioNTech vaccine, which was recently approved for children ages 12 – 15.

“Vaccines are going to unequivocally be much more beneficial outweighing this very low, if conclusively established, risk.” Dr. Amesh Adalja, senior scholar at the Johns Hopkins Center for Health Security, said of the CDC study.

With Post wires