April 11, 2022
Cardiac complications that stem from either a COVID-19 infection or vaccination are rare, but they are more likely to occur after after infection, new research shows.
The study, published by the U.S. Centers for Disease Control and Prevention, found this to be true across all ages groups and genders. The findings provide important context for balancing the risks and benefits of COVID-19 vaccines, researchers said.
Study author Dr. Anuradha Paranjape, vice chair of clinical affairs at Temple Health, stressed that the vaccines are safe and effective.
"They are one of the many tools we have," Paranjape said. "Even though we have antiviral medications, they have to be given in a certain time frame. Prevention is better than treatment."
The study examined the medical records of more than 15 million people ages 5 and older. The study compared the risk of heart complications after COVID-19 infection to those that followed the first and second dose of the Pfizer and Moderna vaccines. Temple was one of 40 health care systems involved in the research.
Multisystem inflammatory syndrome, a rare but serious complication of COVID-19, also frequently involves the heart.
The risk of myocarditis – inflammation of the heart – after vaccination has been highest among young males. In February, the CDC advised males ages 12-39 to wait eight weeks between their first and second vaccine doses to reduce the risk of myocarditis in light of research suggesting a longer wait time diminished risk.
The CDC study found teenage boys have the highest risk of heart complications after vaccination. But their risk after infection was two to six times higher than after vaccination.
Young men ages 18-29 had seven to eight times the risk of heart complications after infection.
Two studies from Israel and the United Kingdom also found higher risk for myocarditis after COVID-19 compared with the vaccines.
The reason that cardiac complications are more of a risk after infection is unclear. Paranjape said the CDC study was not designed to answer that question.
The incidence of Multisystem Inflammatory Syndrome was only calculated for infections because it rarely occurs after vaccination and, when it has, there has been evidence of a previous infection, researchers said.