The Centers for Disease Control and Prevention said Thursday it received reports of eight cases of a heart inflammation called myocarditis in children ages 5 to 11 who had been vaccinated against COVID-19 with Pfizer-BioNTech.
The agency said there had been over 7 million vaccine doses in the 5-11 age group at the time it examined the data, with 5.1 million first doses and 2 million second doses.
The cases had “a mild clinical course,” the CDC said, as reported by Reuters.
The cases were reported in the U.S. Vaccine Adverse Event Reporting System (VAERS) and presented by the CDC to a panel of its expert advisers.
In November, the CDC provided an update after discovering rare cases of myocarditis and pericarditis in relation to the COVID-19 vaccine. Pericarditis is inflammation of the outer lining of the heart.
According to VAERS, symptoms for both heart inflammations include chest pain, shortness of breath and feelings of having a fast-beating, fluttering or pounding heart. Reported cases have occurred in young adults and male adolescents.
Most cases have occurred within a week after receiving the Pfizer-BioNTech or Moderna shots, especially in male adolescents and young adults.