Individuals concerned about getting another bout of Myocarditis following the Pfizer vaccine need not be worried, as a new study indicates that COVID shots do not increase the risk of myocarditis recurrence in previously diagnosed patients.

A small study, to be presented at ESC Acute Cardiovascular Care 2022, concluded that SARS-CoV-2 immunization in patients who previously had an inflamed heart muscle is not associated with a recurrence of the disease or other major adverse effects.

“These results provide reassuring data that may encourage patients with a history of myocarditis to get vaccinated against SARS-CoV-2,” says study author Dr. Iyad Abou Saleh, noting “that the majority of patients in our study received the BNT162b2 mRNA vaccine and therefore the findings may not apply to other vaccines.”

Myocarditis is a condition in which the heart muscle becomes inflamed. Fatigue, chest pain, shortness of breath, and fast heartbeats are all signs and symptoms. Inflammation can impair the heart’s ability to pump blood and lead to arrhythmias (irregular heartbeats). The global prevalence is estimated to be between 10 to 106 instances per 100,000 people. Virus infection is the most common cause of myocarditis.

In the scientific literature, there have been a few incidences of myocarditis following COVID shots, with a rate of 2.1 cases per 100,000 people. However, there is a limited research available about the risk of myocarditis reappearance after SARS-CoV-2 vaccination in patients who have previously had the disease.

“Our experience shows,” as the author of the study points out, “that in some situations patients have avoided vaccination because they, or their GP, were afraid it could cause another bout of myocarditis.”

“We hypothesised that SARS-CoV-2 vaccination would not increase the risk of myocarditis recurrence in patients who had the condition in the past.”

The researchers looked at all patients with acute myocarditis who were admitted to Hospices Civils de Lyon in the last five years (from January 2016 to June 2021). Patients were called by phone and asked if they had been vaccinated, which vaccine they had received, how many times they had received it, and if they had had any side effects. Patients were also questioned if they were now infected with COVID-19 or had previously contracted it.

The study included 142 patients who had previously been diagnosed with acute myocarditis. The average age was 31 years, and 20.3 percent of the participants were female. Vaccination status was known for 71 of them (50 percent), with 55 being vaccinated and 16 being unvaccinated. Fear of recurrence of myocarditis was cited as the main reason for not obtaining the immunization (12 patients, 75 percent of non-vaccinated patients). For 66 cases, vaccination status was unknown, and five patients had died prior to the COVID-19 outbreak.

Twelve of the immunized patients received one dosage and 43 received two doses. BNT162b2 mRNA was used to vaccinate the majority of the patients (53 patients, 96.4 percent ). The mRNA-1273 vaccination was given to one patient, while the Ad26.COV2-S [recombinant] vaccine was given to the other.

Medical records were also used by the researchers to acquire information regarding side effects following vaccination. Serious occurrences such as mortality, arrhythmias, and recurrent myocarditis were among them. There were no major side effects with the SARS-CoV-2 vaccine.

Dr. Abou Saleh adds: “We showed that SARS-CoV-2 vaccination in patients with a history of acute myocarditis is not associated with a risk of recurrent myocarditis or other serious side effects. Our results should be interpreted with caution due to the small number of patients and the predominant use of one type of vaccine.”

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