Swelling of the heart appears to be a very rare side effect that primarily strikes young people after vaccination for COVID-19, the side effect seems to be more common in teen boys and young men than in older adults and women and may occur in 16 cases for every 1 million people who got a second dose, said Tom Shimabukuro, MD, MPH, deputy director of the CDC’s Immunization Safety Office, who presented information on the cases at a meeting of an expert panel that advises the US Food and Drug Administration (FDA) on vaccines.
Telltale symptoms include chest pain, shortness of breath, and fever.
The issue of myocarditis weighed heavily on the Vaccines and Related Biological Products Advisory Committee’s considerations of what kind and how much data might be needed to green light use of a vaccine for COVID in children. Because the rates of hospitalization for COVID are low in kids, some felt that the FDA should require at least a year of study of the vaccines in clinical trials, the amount of data typically required for full approval, instead of the 2 months currently required for emergency use authorization. Others wondered whether the risks of vaccination — as low as they are — might outweigh the benefits in this age group.
Out of more than 12 million doses administered to youth ages 16 to 24, the CDC says it has 275 reports of heart inflammation following vaccination in this age group. The CDC has analysed a total 475 cases of myocarditis after vaccination in people under age 30 that were reported to VAERS.
The vaccines linked to the events are the mRNA vaccines made by Pfizer and Moderna. The only vaccines currently authorized for use in adolescents are made by Pfizer. Because the Pfizer vaccine was authorized for use in kids as young as 12 last month, there’s not yet enough data to draw conclusions about the risk of myocarditis in kids ages 12 to 15.
Cody Meissner, MD, a pediatric infectious disease specialist at Tufts University, Boston, Massachusetts, and a member of the FDA committee said in the committee’s discussion that his own hospital had recently admitted a 12-year-old boy who developed heart swelling 2 days after the second dose of vaccine with a high level of troponin, an enzyme that indicates damage to the heart. His level was over 9. “A very high level,” Meissner said.
In addition to the information presented at the FDA’s meeting, doctors at Oregon Health and Science University recently described seven cases in teens — all boys — who developed heart inflammation within 4 days of getting the second dose of the Pfizer vaccine.