Uptick in cases of myocarditis in newborns in Wales linked to enterovirus, not COVID-19 vaccines

An unusual spike in the number of newborns in the U.K. developing myocarditis — inflammation of the heart muscle — is fueling online misinformation about COVID-19 vaccines. 

A May 21 post shared on Instagram drew an unsubstantiated link between a World Health Organization announcement and the COVID-19 vaccines. 

"Remember when they forced the Covid vaccine on pregnant women saying it was ‘safe and effective’ despite having zero long-term studies proving so?" read the posted screenshot. It was immediately followed by a Zero Hedge headline that read: "WHO Warns Of ‘Unusual’ Surge in Severe Myocarditis in Babies."

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(Screenshot from Instagram.)

The article on Zero Hedge — a blog website with a history of publishing misinformation — focused on a May 16 WHO disease outbreak alert about an uptick in myocarditis cases among newborns in the United Kingdom. But the myocarditis cases were associated with enterovirus infections, not COVID-19 or the vaccines. 

From June 2022 to April 2023 in Wales, 10 newborns younger than 28 days old who were hospitalized and tested positive for enterovirus infections also developed myocarditis, according to the WHO. (The WHO’s statement was first published May 16, but it was updated with corrected numbers May 17.)

"One baby remains in hospital; eight are being managed as outpatients and, very sadly, one baby died," announced Eluned Morgan, the minister for health and social services in Wales, saying that her thoughts were with the families. 

In its statement, the WHO said that the most common cause of myocarditis is viral infection, including infection from enteroviruses, which are among the world’s most prevalent class of viruses. The U.S. Centers for Disease Control and Prevention and Johns Hopkins Medicine also list infection as the most common cause of myocarditis.

Dr. Shamez Ladhani, a consultant pediatrician at the U.K. Health Security Agency, described enterovirus as "a common infection of childhood," in a statement to PolitiFact. Enterovirus infections can cause a range of illnesses such as hand, foot, mouth disease or viral meningitis, Ladhani said.

"In very young babies, enterovirus can, on rare occasions, lead to a severe complication called myocarditis — which causes inflammation of the heart," Ladhani said. "Most babies and children recover completely from this." 

The reported increase in severe myocarditis associated with enterovirus infection among newborns was unusual, the WHO reported. In the six years before June 2022, only two similar myocarditis cases were identified in the South Wales region, the WHO said.

But at this stage, there is no reason to think that the increase in myocarditis cases among newborns is linked to COVID-19 vaccines, a WHO spokesperson told PolitiFact. 

The CDC and U.K. health authorities recommend that people who are pregnant get vaccinated against COVID-19. A growing body of evidence supports that COVID-19 vaccination during pregnancy is safe and effective and does not cause fertility problems, according to the CDC.

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In some rare cases, myocarditis has been linked to mRNA COVID-19 vaccines. Those cases, which were often mild and responded to treatment, most frequently occurred in adolescent and young adult men within seven days of receiving the second dose of an mRNA vaccination, the CDC reported. 

Research shows that a person’s risk of developing myocarditis is higher after COVID-19 infection than it is after vaccination against COVID-19.

U.K. health authorities are investigating the newborn cases to assess whether they could be linked to the coronavirus pandemic, the WHO spokesperson said.

Wales is "engaged in a clinical study to understand this incident further and learn lessons, including changes in how infections circulate and population immunity following the pandemic," said Morgan, the Welsh health minister. "Parents should be reassured that although there has been an increase in cases, this is still an extremely rare occurrence."

Public Health Wales was working closely with the Noah’s Ark Children’s Hospital for Wales’ pediatric team to investigate, she said. 

The health risk for the general population remains low, according to the WHO’s assessment. In some situations, the WHO said it might recommend closing child care facilities or schools to reduce the intensity of enterovirus transmission.

An image shared on Instagram suggested that people getting vaccinated against COVID-19 while pregnant drove an increase in myocarditis cases in babies.

U.K. health authorities are investigating an uptick in myocarditis cases associated with enterovirus infections. The WHO sent out an alert about the myocarditis cases, but it did not identify a link between them and COVID-19 vaccines. A WHO spokesperson said existing research does not suggest a link.

We rate these claims False.