Published on 8 November 2021

    Vaccine-related myocarditis is a rare side effect of the mRNA COVID-19 vaccine. Most people who develop this condition have mild symptoms and recover without long-lasting issues.

    To avoid aggravating this condition in those at risk, the Ministry of Health (MOH) has recommended that people should avoid strenuous physical activity for two weeks after receiving either of their mRNA Covid-19 vaccination doses.

    How do I determine the physical activities to avoid?VACCINERISKfor mRNA vaccines in the US (Comparable to the risk of anaphylaxis observed in Singapore)mRNA TO DATELow Intensity: You can walk and sing while exercising without feeling out of breath.High Intensity: 70% to 85% MHR (OR you are unable to speak in complete sentence during the workout)Examples of high intensity exercises to avoidCircuit trainingVigorous forms of weight trainingSprintingIncreasing the distance of swimmingExamples of light intensity exercises to considerStretchingLight walkingHouseworkModerate Intensity: 50-70% of your maximum heart rate (MHR), calculated by 220 - AgeExamples of moderate intensity exercises to avoidWeight trainingBrisk walkingSlow jog (5-6km/hr)CyclingSwimming

    What is Myocarditis?

    Myocarditis is the inflammation of the heart muscle. This happens when the body's immune system causes inflammation in response to an infection or some other trigger, such as a vaccine response.

    Signs of myocarditis include:

    • Chest pain

    • Shortness of breath

    • Feelings of having a fast-beating, fluttering, or pounding heart

    Seek medical attention if you are experiencing any of these symptoms within the week after your COVID-19 vaccination.

    Is the mRNA COVID-19 vaccine safe?

    With the very low risk of myocarditis, vaccination is still safe. The known and potential benefits of COVID-19 vaccination outweigh the known and potential risks of vaccination. COVID-19 is more likely to lead to illness, and severe complications as well as long-term health problems, hospitalisation, and even death. Those who develop myocarditis generally respond well to treatment. If you have concerns about COVID-19 vaccination, talk with your doctor about the best option and management of risks.

    In consultation with Professor Tan Huay Cheem, Senior Consultant, Department of Cardiology, National University Heart Centre, Singapore (NUHCS).

    Download the full infographics here.


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