The Health Sciences Authority (HSA) has reported four cases of young men experiencing heart inflammation after receiving the second dose of the Covid-19 vaccine.
The expert committee on the Covid-19 vaccine (EC19V ) said in a release on June 11 that the men, aged 18 to 30 years old, have all recovered or discharged well from the hospital following their conditions of myocarditis or pericarditis.
Myocarditis is the inflammation of the heart muscle, while pericarditis is the inflammation of the heart's outer lining.
Most of the cases were reported to have occurred within a few days of receiving the second dose of the vaccine.
Myocarditis and pericarditis are separate and distinct conditions from heart attacks, which are caused when blood flow to the heart is blocked.
Avoid strenuous physical activity for one week after the second dose
The currently available data suggest that there may be "a very small risk" of myocarditis and pericarditis after the second dose of an mRNA vaccine, particularly in young men.
As a precaution, vaccinated persons, including adolescents and younger men, should avoid strenuous physical activity for one week after their second dose.
They should also seek medical attention promptly if they develop chest pain, shortness of breath or abnormal heartbeats.
Benefits of Covid-19 vaccine outweigh the risks
However, the expert committee said that the benefits of receiving the Covid-19 vaccine outweigh the risks of vaccination:
"Most cases are mild, recover without the need for significant intervention and do not suffer any long-term effects, although very rarely, severe cases may result in damage to the heart muscles."
Therefore, the benefits of the vaccine continue to outweigh the risks, the committee added.
Heart inflammation after the second dose of Covid-19 vaccinations has been observed in Israel and the U.S in young men below 25 years old.
The risk of this has been estimated to be 1.6 cases per 100,000 doses for mRNA vaccines in the U.S. — comparable to the risk of anaphylaxis (a severe allergic reaction) observed in Singapore.
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