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U.S. public health officials claim cases of myocarditis and pericarditis following COVID vaccination are rare — but new research published online in the Journal of American Medical Association (JAMA) shows they may happen more often than reported.
Post-vaccine myocarditis and pericarditis also appear to represent two “distinct syndromes,” Dr. George Diaz, with the Providence Regional Medical Center Everett, told Medscape Cardiology.
The records, obtained from 40 hospitals in Washington, Oregon, Montana and California, showed 20 people had vaccine-related myocarditis (1.0 per 100,000) and 37 had pericarditis (1.8 per 100,000).
A recent report, by the Centers for Disease Control and Prevention (CDC), based on data from the Vaccine Adverse Events Reporting System (VAERS), suggested an incidence of myocarditis of about 4.8 cases per 1 million following receipt of an mRNA COVID vaccine.
The median age of the CDC report’s cohort was 57 years, and 59% were women. Only 77% received more than one dose. Fifty-three percent received Pfizer, 44% Moderna and 3% received Johnson & Johnson’s (J&J) COVID vaccine.
Myocarditis is inflammation of the heart muscle that can lead to cardiac arrhythmia and death. According to researchers at the National Organization for Rare Disorders, myocarditis can result from infections, but “more commonly the myocarditis is a result of the body’s immune reaction to the initial heart damage.”
The new JAMA study showed a “similar pattern [to the CDC study], although at higher incidence [of myocarditis and pericarditis] after vaccination, suggesting vaccine adverse event under-reporting.”
The JAMA report also stated: “Additionally, pericarditis may be more common than myocarditis among older patients.”
“Our study resulted in higher numbers of cases probably because we searched the EMR, and [also because] VAERS requires doctors to report suspected cases voluntarily,” Diaz told Medscape. Also, in the governments’ statistics, pericarditis and myocarditis were “lumped together,” Diaz said.
According to Tracy Høeg, physician, epidemiologist and associate researcher at UC Davis, the results of the JAMA study are telling, as recent rates correlate with vaccination.
“An important thing I would say is COVID itself does not appear to be correlated with an uptick,” Høeg said in a tweet.
A telling figure looking at myocarditis rates at 40 hospitals in the Western US w/ recent ⬆️ rates correlated w/vaccination. An important thing I would say is COVID itself does not appear to be correlated with an uptick.
— Tracy Høeg, MD, PhD (@TracyBethHoeg) August 5, 2021
The researchers calculated the average monthly number of cases of myocarditis or pericarditis during the pre-vaccine period of January 2019 through January 2021 was 16.9 compared with 27.3 during the vaccine period of February through May 2021.
The mean numbers of pericarditis cases during the same periods were 49.1 and 78.8.
The authors said limitations of their analysis include potential missed cases outside care settings and missed diagnoses of myocarditis or pericarditis, which would underestimate the incidence, as well as inaccurate EMR vaccination information.
“Temporal association does not prove causation, although the short span between vaccination and myocarditis onset and the elevated incidence of myocarditis and pericarditis in the study hospitals lend support to a possible relationship,” the authors wrote.
Myocarditis more common in men
The 20 myocarditis cases occurred a median of 3.5 days after vaccination. Eleven occurred after receiving Moderna’s vaccine and nine occurred after Pfizer. Fifteen cases were in men, and the median age was 36 years.
Four individuals developed myocarditis symptoms after the first vaccination (20%) and 16 (80%) after the second dose. Nineteen patients (95%) were admitted to the hospital and were discharged after a median of two days. None of the 20 patients died.
At last available follow-up (median, 23.5 days after symptom onset), 13 patients (65%) had a resolution of their myocarditis symptoms and seven (35%) were improving.
Pericarditis more frequent after Pfizer vaccine
The 37 pericarditis cases occurred a median of 20 days after the most recent COVID vaccination. Twenty-three cases (62%) occurred with Pfizer, 12 (32%) with Moderna and two (5%) with J&J’s vaccine.
Fifteen people developed pericarditis after the first vaccine dose (41%) and 22 (59%) after the second. Twenty-seven (73%) of the cases occurred in men with a median age of 59 years.
Thirteen (35%) patients were admitted to the hospital with a median hospital stay of one day. No patient died.
Kids and myocarditis
In another, small case series published online in JAMA Aug. 10, researchers examined 15 children who were hospitalized with myocarditis after receiving Pfizer’s vaccine. Boys were most commonly affected after the second dose.
Three patients had ventricular systolic dysfunction — a common and serious complication of myocardial infarction that leads to greatly increased risks of sudden death and of heart failure.
Twelve patients had late gadolinium enhancement — a result of cardiac injury — on cardiac magnetic resonance imaging.
There were no deaths, and all but one patient had normal echocardiogram results on follow-up one to 13 days after hospital discharge.
The researchers concluded patients were mildly affected, but long-term risks associated with post-vaccine myocarditis remain unknown and larger studies with longer follow-up are needed to inform recommendations for COVID vaccination in children.
According to the latest data from VAERS, there have been 2,018 U.S. reports of myocarditis and pericarditis following COVID vaccines, with 1,275 cases attributed to Pfizer, 667 cases to Moderna and 71 cases to J&J’s COVID vaccine.
The VAERS website states underreporting is one of the main limitations of a passive surveillance system like VAERS. The website states: “The term underreporting refers to the fact that VAERS receives reports for only a small fraction of actual adverse events.”
“This is why it’s, at the very least, absolutely critical for medical necessity to be established through COVID-19 antibody testing so that already immune COVID-recovered children are spared an unnecessary vaccination,” Noorchasm said. “I also suspect that spreading out the vaccine dosing to 6-8 weeks will reduce the incidence of this complication.”
Noorchasm said any child who complains of chest pain following vaccination ought to have his/her troponin levels evaluated to rule out myocardial injury — irrespective of which vaccine dose they’ve received.
On Aug. 12, The Defender reported about a 14-year-old boy, Aiden, who developed myocarditis after receiving Pfizer’s vaccine. Aiden’s mother, Emily Jo, said she was aware of the potential side effect of heart inflammation, but the CDC said it was very rare and mild.
“What they didn’t explain is that mild means hospital care and follow-up care indefinitely,” Jo said.
But the biggest problem, Jo said, is the CDC does not explain what mild myocarditis means. “Aiden’s cardiologist told us no case of myocarditis is ‘mild.’ That’s like saying a heart attack is mild,” her son’s doctor told her.
Another sad story! Mom so proud that her 14-year-old son could get the COVID vaccine… but now doctors confirm her son meets the criteria for having post-vaccine myocarditis.
— Robert F. Kennedy Jr (@RobertKennedyJr) August 11, 2021
On June 25, the U.S. Food and Drug Administration (FDA) added a warning to patient and provider fact sheets for Pfizer and Moderna COVID vaccines suggesting an increased risk of myocarditis and pericarditis — particularly following the second dose and with onset of symptoms within a few days after vaccination.
The FDA’s update followed a review of information and discussion by the Advisory Committee on Immunization Practices (ACIP), a committee within the CDC that provides advice and guidance on effective control of vaccine-preventable diseases, during a June 23 meeting where the committee acknowledged 1,200 cases of heart inflammation in 16- to 24-year-olds, and said mRNA COVID vaccines should carry a warning statement.
Dr. Elizabeth Mumper, a pediatrician who has seen many patients experience vaccine adverse events in her practice, listened to the entire June 23 ACIP meeting.
“I was surprised that a working document was presented in which ACIP was leaning toward recommending a second COVID vaccine in patients who experienced heart inflammation after the first dose, as long as the patient had improved. I was also surprised that some ACIP committee members seemed to be making the assumption that the cases of myocarditis and pericarditis would not cause long-term harm. We simply do not have the evidence to make COVID vaccine decisions on that assumption.”
Mumper said she’s worried there will be many more cases of heart inflammation as the vaccine is rolled out to younger and younger children.
Health officials said the benefits of receiving a COVID vaccine still outweigh any risks. But physicians and other public commenters during the June 23 meeting accused the CDC of exaggerating the risk of COVID to young people, and minimizing the risk of the vaccines.