More Study Urged After 7 Teen Boys Suffer Heart Inflammation After Getting COVID-19 Vaccine

Several teenage boys who experienced non-life-threatening heart inflammation after receiving the second dose of the COVID-19 vaccine have prompted health officials to look into whether the cases could be a rare vaccine side effect in teens and young adults.

According to an article published online Friday in Pediatrics, seven teenage boys in the U.S. experienced heart inflammation following the second dose of the Pfizer shot, but more research is required to prove the cases are linked to the vaccine.

None of the boys, who ranged in age from 14 to 19, were critically ill, but imaging tests showed a type of heart muscle inflammation called myocarditis. They all received second Pfizer doses in April or May.

They were all well enough to go home after two to six days in the hospital and are "doing pretty well," according to Dr. Preeti Jaggi, an Emory University infectious disease specialist and co-author of the Pediatrics report.

Jaggi continued follow-up is necessary to monitor the outcomes of the seven boys, but it is most likely the inflammation was temporary.

For more reporting from the Associated Press, see below:

Signage is seen near a NYC mobile vaccination clinic bus near Brighton beach on May 29 in New York City. Jeenah Moon/Getty Images

Only one of the seven boys in the Pediatrics report had evidence of a possible previous COVID-19 infection and doctors determined none of them had a rare inflammatory condition linked with the coronavirus.

The cases echo reports from Israel in young men diagnosed after receiving Pfizer shots.

The U.S. Centers for Disease Control and Prevention alerted doctors last month it was monitoring a small number of reports of heart inflammation in teens and young adults after the mRNA vaccines, the kind made by Pfizer and Moderna.

The CDC hasn't determined if there's really a link to the shots, and continues to urge everyone 12 and older get vaccinated against COVID-19, which is far riskier than the vaccine. The Pfizer vaccine is available to those as young as 12; the Moderna shot remains cleared only for adult use.

This kind of heart inflammation can be caused by a variety of infections, including a bout of COVID-19, as well as certain medications—and there have been rare reports following other types of vaccinations.

Authorities will have to tease out whether cases following COVID-19 vaccination are occurring more often than that expected "background rate."

For now, the CDC says most patients were male, reported symptoms after the second dose, and their symptoms rapidly improved.

"I think we're in the waiting period where we need to see whether this is cause-and-effect or not," said John Grabenstein of the Immunization Action Coalition, a former director of the Defense Department's immunization program.

A Pediatrics editorial noted that among U.S. children under age 18, there have been over 4 million COVID-19 cases, more than 15,000 hospitalizations and at least 300 deaths.

The CDC on Friday reported COVID-19-related hospitalizations of kids aged 12 to 17 fell early this year but rose again in March and April. Possible reasons include the spread of new virus variants, more kids going back to school, or the relaxing of mask and social distancing rules, agency researchers said.

While infected kids are less likely to become critically ill than adults, the CDC data on about 200 hospitalizations from 14 states show one-third were treated in intensive care units. The report had no mention of any heart involvement.

CDC Director Dr. Rochelle Walensky said the hospitalizations raise concerns and urged parents to get their kids vaccinated.

"Vaccination is our way out of this pandemic," she said in a statement.

The Pediatrics editorial said the heart inflammation cases warrant more investigation but added that "the benefits of vaccination against this deadly and highly transmissible disease clearly far outweigh any potential risks."

Editorial co-author Dr. Yvonne Maldonado, head of an American Academy of Pediatrics infectious diseases committee, is involved in Pfizer vaccine studies, including a COVID-19 vaccine study in children.

In this May 15 file photo, empty vials of the Pfizer COVID-19 vaccine lie in a box during a vaccine campaign in Ebersberg near Munich, Germany. Health authorities are trying to determine whether heart inflammation that can occur along with many types of infections could also be a rare side effect in teens and young adults after the second dose of COVID-19 vaccine. Matthias Schrader, File/AP Photo