Myocarditis After COVID Vaccination: Should You Be Concerned?

The information provided by Singapore Heart Foundation is for educational purposes only. It should not be substituted for professional health care. Please consult your doctor for professional advise.

A number of reports have recently emerged on the occurrence of myocarditis and pericarditis after COVID vaccination. Six patients in Singapore have been reported to suffer these conditions out of nearly 2.7 million people who have received the mRNA COVID vaccines. The USA Centre for Disease Control and Prevention (CDC) has also reported 475 cases of myocarditis and pericarditis in people aged 30 years or younger after receiving the vaccination. Here’s what you need to know about heart inflammation and its possible link to the mRNA vaccines:

What are myocarditis and pericarditis?

Myocarditis is the inflammation of the heart muscles or myocardium. Pericarditis is the inflammation of the outer covering of the heart or the pericardium.

They occur more often in men than in women.

Symptoms include:

  • Sharp chest pain, characterised by a sudden and intense burning chest pain exacerbated by deep breathing. This pain varies with position, and patients may feel uncomfortable lying down but feel relieved sitting up and leaning forward.
  • Breathlessness
  • Dry cough
  • Palpitations

Cases extremely rare, effects mild
Among the patients who developed myocarditis after COVID vaccinations, most were young (under the age of 30 years old), males (accounting for 80%) who developed symptoms 2 to 4 days after receiving the second dose of the vaccines. Though most reported cases were related to the mRNA vaccines, there have been sporadic reports from other vector-based vaccines.

While most agree that there is strong evidence of the association between the vaccines and myocarditis, the actual causal relationship has yet to be fully established. The mechanism of myocarditis is currently unknown. It may be related to the reactogenic side effects of the vaccines, just like the other symptoms of lethargy, fever, muscle aches, and headaches, which some patients may experience after receiving the injections.

The diagnosis of myocarditis is made based on the patient’s history, supported by electrocardiogram (ECG) changes, blood biomarker changes such as troponin elevation and classic images obtained on magnetic resonance imaging (MRI) of the heart. Most patients recover within a week after the onset of symptoms, either spontaneously or with some painkillers or anti-inflammatory medicines. There have not been any reported adverse long term consequences.

What precaution should you take?

It is advisable to avoid strenuous exercises within one week of vaccination, have adequate rest and keep well-hydrated. Should there be any suggestion of chest pain, shortness of breath or abnormal heartbeats, medical advice should be sought.

It is important to understand that COVID-19 viral infection can cause myocarditis, which presents with much higher cardiac risk to patients, even if they are young. The real incidence of acute myocarditis after mRNA COVID-19 vaccine appears to be extremely low and does not change the highly favourable risk-benefit profile of COVID vaccination.

Article is contributed by Prof Tan Huay Cheem, Chairman of Singapore Heart Foundation; Senior Consultant, Department of Cardiology and Director of National University Heart Centre, Singapore.