October 02, 2025
Briana Sanchez/El Paso Times; USA Today Network
Children who get COVID-19 twice are at much higher risk of developing serious heart, kidney and other health issues associated with long COVID than children only infected once, new research from the University of Pennsylvania shows. Pictured here, a child receives a COVID vaccine.
Children who get COVID-19 more than once are at higher risk of developing long COVID, new research from the University of Pennsylvania suggests.
Specifically, the study published Tuesday in The Lancet Infectious Diseases found that children who get COVID twice are two times more likely to develop long COVID compared to children who only get COVID once.
"Many had hoped reinfections of COVID would be milder or carry less long-term risk, but we found increased risks for a broad range of conditions, challenging the assumptions many had that children bounce back quickly," said Bingyu Zhang, a researcher at the Penn Computing, Inference and Learning lab.
A lack of a universal definition of long COVID has hindered research, diagnosis and treatment of the disease, according to a study published in August in JAMA Open Network. But generally, long COVID is associated with health complications that last more than three months after a COVID infection. Long COVID has been linked to hundreds of persistent symptoms, including extreme fatigue, issues with taste and smell, digestive problems, mood disorders and heart disease, according to the Mayo Clinic.
Most long COVID research has focused on adults, so the Penn scientists decided to focus on children, analyzing data from more than 400,000 pediatric patients at 40 hospitals between 2021 and 2023. The researchers found that among patients under 21 who had COVID once, there were 904 cases of long COVID per million people. The rate jumped to 1,884 cases per million among children infected with COVID twice.
"Reinfection really increases the risk," Yong Chen, director of the Penn Computing, Inference and Learning Lab, told The New York Times. "Your body really has a memory system and is really going to be hurt from recurrent infection."
Pediatric patients infected with COVID twice were 3 1/2 times more likely to develop myocarditis, a rare inflammatory heart condition that can lead to heart failure and death.
A second infection with COVID also doubled children's risk of developing blood clots and increased the chance of having severe kidney damage, abnormal heartbeats and severe fatigue, the study found.
"The results of this study further support one of the strongest reasons I give patients, families and physicians about getting vaccinated: More vaccines should lead to fewer infections, which should lead to less long COVID," said Dr. Ravi Jhaveri, head of Pediatric Infectious Diseases at Ann & Robert H. Lurie Children's Hospital of Chicago.
The study was part of the federal RECOVER initiative designed to better understand the effects of long COVID.
Data used for the study was from patients who had been infected with the omicron variant of COVID, a version of the virus that has persisted and still infects and reinfects people today, the researchers said.
