The risk of developing myocarditis, an inflammatory heart disease, is six times higher in adolescent males who have contracted Covid-19, compared to the likelihood that the rare side effect will emerge after receiving the Pfizer / BioNTech vaccine , according to a new American study. .
The research – which has not yet been peer-reviewed – suggests that the risk of developing myocarditis after catching Covid in boys aged 12 to 17 is much greater than the risk that can emerge from the vaccine.
The data comes around 10 days after the UK Joint Committee on Immunization and Immunization (JCVI) recommended that 12 to 17 year olds only be offered a Covid vaccine if they are extremely vulnerable or live with someone at risk. .
The decision, the committee suggested, was cautious, given new reports from the UK and elsewhere of rare but serious heart complications such as myocarditis after vaccination with the Pfizer / BioNTech vaccine in young people. .
The benefits of universal vaccination in those under 18 do not outweigh the potential risks, JCVI members said, suggesting that the risk of “long Covid” was also low in this age group.
The Pfizer / BioNTech vaccine has been cleared for people aged 12 and over in the UK by the Medicines and Health Products Regulatory Agency since early June. Many other countries, including the United States, Israel and Ireland, have decided to vaccinate their teens.
The latest study, encompassing data gleaned from specific U.S. electronic health records, included people under the age of 19 who were diagnosed with Covid between April 2020 and March 2021.
Six of 6,846 (0.09%) of men with Covid aged 12 to 17 in the study developed myocarditis, which translates to 876 cases per million. But given that not all cases of Covid and myocarditis are likely counted in health records, and based on some assumptions, researchers have adjusted the figure to 450 per million cases.
For women aged 12 to 17, there were three cases of myocarditis out of 7,361 patients (0.04%) in the study. After applying similar adjustments to account for missed cases, the researchers estimated that there were 213 cases per million in this subgroup.
Existing data from the United States and Israel suggests that the risk of myocarditis after mRNA vaccines was highest in the subgroup of males aged 12 to 17, with 76.5 cases per million vaccinated.
Adam Finn, professor of pediatrics and member of JCVI, suggested that there was a lot of uncertainty around the study and that a clear case definition of myocarditis was missing from the analysis. “So far, no one has seen a single case of Covid-associated myocarditis in an adolescent in the UK,” he added.
Dr Maggie Wearmouth, another JCVI member, called the study’s results “thought-provoking” and said the committee had discussed the research at length on Thursday. JCVI continues to review incoming and existing evidence and discuss the way forward, she said, adding that if there are any changes in the recommendations, they will be released through official channels in due course.
Martin McKee, professor of European public health at the London School of Hygiene and Tropical Medicine, said that while the study has some limitations, “it serves as a reminder of the significant risks this disease poses for young people.”
The virus still circulates widely – especially among young people – and the more infectious Delta variant makes it much more difficult to avoid catching the virus other than by getting vaccinated, added consultant Dr Peter English. retired in Communicable Disease Control and former Chairman of the BMA’s Public Health Medicine Committee.
“This suggests that the overall risk of myocarditis is likely to be lowered by being vaccinated, because the risk of disease is so much greater than the risk of vaccination. “