What is known about rare cases of heart inflammation in teens, young adults who got two-shot COVID vaccine.

CDC investigating cases of heart inflammation in teens, young adults who got two-shot COVID vaccine. Here's what we know. The news comes a few weeks after the FDA authorized Pfizer’s vaccine for minors 12 and older. Moderna's vaccine is authorized for people 18 and older. Adrianna Rodriguez USA TODAY

Health officials are looking into reports of heart problems occurring in young adults and teenagers who have received the mRNA COVID-19 vaccines, according to a vaccine safety group with the Centers for Disease Control and Prevention.

In a May 17 meeting, the group presented reports of the heart condition, called myocarditis, to the CDC's Advisory Committee on Immunization Practices from safety data collected by the Department of Defense, the Vaccine Adverse Event Reporting System (VAERS), and Vaccine Safety Datalink (VSD).

The news comes a few weeks after the Food and Drug Administration authorized Pfizer’s COVID-19 vaccine for minors 12 and older. Moderna's vaccine is currently authorized for people 18 and older. The safety group did not specify which vaccine was given in these cases. 

“It’s terrific that things are being transparent. … It shows the surveillance systems are working,” said Dr. Lawrence Kleinman, professor and vice chair of the department of pediatrics at Rutgers Robert Wood Johnson Medical School.

While little is known, here's what health experts say about these cases. 

The vaccine safety group says the “relatively few” reports of myocarditis “appear to be mild” and are below the expected baseline rates. 

Among the cases, the heart condition appeared in adolescents and young adults, and more often in men than women. Symptoms typically appeared within four days after the second dose. Follow-up on the cases is ongoing, the work group said. ...

Signs and symptoms of myocarditis in children may include fever, fainting, breathing difficulties, rapid breathing and rapid or abnormal heart rhythms, called arrhythmias.

“It’s not common (in children) but neither is it a rare thing where its presence can be said to be definitively associated with the vaccine,” Kleinman said.

Myocarditis can be caused by a whole host of viruses, including COVID-19, said Dr. Federico Laham, medical director for Orlando Health Arnold Palmer Hospital for Children Infectious Diseases. ...