Young males are more likely to report heart damage following vaccination with an mRNA COVID-19 vaccine, and the damage is more likely to be reported after the second dose, according to research published May 25 in The BMJ.
The researchers based their conclusion on a systematic review of scientific literature and of vaccine injury data collected by passive reporting systems in the U.K., Europe and U.S.
The goal of the systematic review was to better understand risk factors for developing myocarditis and pericarditis following vaccination with Pfizer-BioNTech and Moderna COVID-19 vaccines.
Myocarditis is an inflammation of the heart muscle and pericarditis is an inflammation of the lining that surrounds the heart, according to the World Health Organization (WHO).
The Pfizer-BioNTech and Moderna vaccines were promoted extensively worldwide for use against COVID-19.
READ ALSO: Deaths, injuries, waning efficacy: The latest bad news on COVID vaccines
Many countries have started booster campaigns, “yet these are the first in their class of vaccines to be approved for use, and as such continued monitoring of their safety is required,” the authors of the review said.
According to the review, cases of myocarditis and pericarditis were first identified in Israel, where 148 cases of myocarditis were reported within 30 days of vaccination. The majority of these cases (121, or 81.7%) were reported after the second dose.
Since this safety signal was first detected, multiple countries have reported myocarditis and pericarditis following mRNA COVID-19 vaccines.
By June of last year, both Pfizer and Moderna included a brief warning about heart damage in their Emergency Use Authorization fact sheets for vaccine recipients.
For purposes of the systematic review, the researchers used the U.K. Yellow Card scheme, the U.S. Vaccine Adverse Event Reporting System (VAERS) and the EU’s EudraVigilance. The cut-off date for the searches on cases was mid-March 2022.
For the scientific literature review, the researchers searched PubMed/MEDLINE and Embase up to March 15. They identified records and then removed records that did not fit their eligibility criteria, leaving 32 peer-reviewed studies.
READ ALSO: Supreme Court nullifies mandatory Covid-19 vaccination in India
Case studies, other systematic reviews, and meta-analysis papers were all removed from their systematic review.
Overall, 18,204 reports of myocarditis and pericarditis were submitted to U.K., U.S. and EU regulators during the study period, beginning when the mRNA vaccines first rolled out until mid-March 2022.
According to the Centers for Disease Control and Prevention, 124.12 million people were fully vaccinated with Pfizer and 75.57 million people fully vaccinated with Moderna during the study period.
For Pfizer, this is a reporting rate of 14.70 cases of myocarditis and 9.36 cases of pericarditis per 1 million fully vaccinated individuals. The combined rate of myocarditis and pericarditis is 12.03 cases reported per 1 million fully vaccinated individuals.
For Moderna, there were 12.35 cases of myocarditis and 9.36 cases of pericarditis reported per 1 million fully vaccinated recipients. The combined reporting rate of both myocarditis and pericarditis is 10.86 per 1 million.
In the U.K., there were 1,260 events following Comirnaty and 325 events after Spikevax reported to the U.K.’s Yellow Card scheme. As of March 16, 2022, it was estimated that 26.2 million first doses and 23.6 million second doses of Comirnaty were administered in the U.K.
READ ALSO: Pilots, Cabin Crew suffer COVID-19 vaccine injuries – Aviation Associations protest
The authors calculated there were approximately 48.09 cases of myocarditis and pericarditis per 1 million vaccines who had received at least one dose of Comirnaty.
For Spikevax, approximately 1.6 million first doses and 1.5 million second doses of Spikevax were administered in the U.K. Of those who received at least one dose, 203.13 cases of myocarditis and pericarditis were reported per 1 million vaccinated individuals.
In the EU, 9,211 events following Comirnaty and 2,786 following Spikevax were reported to EudraVigilance.
Approximately 296.05 million people received at least one dose of Comirnaty and approximately 46.56 million received a first dose of Spikevax.
The authors calculated the reporting rates were 14.50 reports of myocarditis and 16.61 reports of pericarditis per 1 million for Comirnaty. The combined reporting rate was 15.56 cases of myocarditis and pericarditis per 1 million people who received at least one dose of Comirnaty.
For Spikevax, the reporting rate was 28.01 reports of myocarditis and 31.83 reports of pericarditis per 1 million vaccines, with a combined reporting rate of 29.92 per million Spikevax recipients.
There were 13,573 events of myocarditis and/or pericarditis reported in the observational studies included in the systematic review of the literature, but these cannot help to calculate the overall rate of these adverse events.
The authors concluded from the above that, “while reporting rates for myocarditis and pericarditis have differed between the spontaneous reporting databases, overall, they demonstrate that these events are very rare (defined as occurring at a rate of less than 1 in 10,000).”