The Centers for Disease Control and Prevention said they are monitoring cases of heart inflammation in young people who have received the COVID-19 vaccine.
The CDC's Advisory Committee on Immunization Practices said in a report on May 17 that the condition, known as myocarditis, seems to occur predominantly in adolescent and young adult men.
The CDC added that it typically appears four days after their second dose of a COVID-19 vaccine.
The CDC added that most cases appear mild, but they are conducting follow-ups of the patients.
"Within CDC safety monitoring systems, rates of myocarditis reports in the window following COVID-19 vaccination have not differed from expected baseline rates," the committee said in a statement.
But members of the COVID-19 Vaccine Safety Technical Work Group felt that healthcare providers should be aware of the reports of the "potential adverse event."
The CDC did not say how many people were affected, but they did recommend further investigation.
