• Posted November 6, 2025

COVID Vaccination Safer For Kids' Heart Health Than Infection, Study Says

The COVID vaccine is safer for kids’ heart health than if they become infected with the coronavirus, a new study has found.

Children who get COVID have an increased risk of rare heart complications including blood clots, heart inflammation and low platelet counts that lasts up to a year after their infection, researchers report in the December issue of the journal, The Lancet Child and Adolescent Health.

By comparison, COVID vaccination caused only a short-term higher risk in heart inflammation that lasted about a month, researchers said.

“Although these conditions were rare, children and young people were more likely to experience heart, vascular or inflammatory problems after a COVID-19 infection than after having the vaccine — and the risks after infection lasted much longer,” lead researcher Alexia Sampri said in a news release. She’s a senior health data scientist with the University of Cambridge in the U.K.

This is an early look that compares the longer-term risks of COVID vaccination with the risks posed by COVID infection, researchers said.

Prior research has shown that vaccination can cause rare cases of myocarditis among young people, but that risk hadn’t been held up against the heart health risks that come with infection, researchers said.

For the study, researchers analyzed health records for nearly 14 million children younger than 18 in England between 2020 and 2022, during the height of the COVID pandemic.

During that period, 3.9 million children and teens had a first COVID diagnosis, and 3.4 million were vaccinated against COVID using mainly the Pfizer-BioNTech jab, researchers said.

The team looked at a short list of specific rare complications that might occur following either COVID infection or vaccination:

• Arterial and venous thrombosis (clots in blood vessels)

• Thrombocytopenia (low levels of platelets in the blood)

• Myocarditis or pericarditis (inflammation of the heart and its surrounding tissue, respectively)

• Systemic inflammatory conditions

After being infected with COVID, kids’ risks for these conditions rose within the first month of infection, researchers found. They were:

• 2.3 times higher for artery clots and nearly 5 times higher for vein clots

• 3.6 times higher for low levels of platelets

• 3.5 times higher for myocarditis or pericarditis

• Nearly 15 times higher for inflammatory conditions

Infected children's risk remained higher for up to 12 months later for vein blood clots (39%), low platelet levels (42%), and myocarditis or pericarditis (42%).

On the other hand, the COVID vaccine increased only the risk of myocarditis or pericarditis by 84%, the study found. That elevated risk lasted for a  month following vaccination, then returned to normal levels.

“Using electronic health records from all children and young people in England, we were able to study very rare but serious heart and clotting complications, and found higher and longer-lasting risks after COVID-19 infection than after vaccination,” said senior researcher Angela Wood, associate director of the British Heart Foundation Data Science Center.

“Whilst vaccine-related risks are likely to remain rare and short-lived, future risks following infection could change as new variants emerge and immunity shifts,” she added in a news release.

Overall, COVID infection led to 2.2 extra cases of myocarditis or pericarditis per 100,000 children, while COVID vaccination caused only 0.9 extra cases per 100,000, researchers said.

“Parents and carers have faced difficult choices throughout the pandemic,” researcher Pia Hardelid, a professor at University College London, said in a news release. “By building a stronger evidence base on both infection and vaccination outcomes, we hope to support families and health care professionals to make decisions grounded in the best available data.”

More information

The U.S. Centers for Disease Control and Prevention has more on COVID vaccination for children.

SOURCE: Health Data Research UK, news release, Nov. 4, 2025