1. The Expert Committee has been closely monitoring international reports that the second dose of mRNA COVID-19 vaccines may be associated with a small risk of myocarditis and pericarditis in young men. We have reviewed the currently available international and local data. Our assessment is that the benefits of receiving the mRNA COVID-19 vaccines, i.e., reduction in COVID-19 infections and severe complications even if infected, continue to outweigh the risks of vaccination.
Myocarditis and Pericarditis with mRNA Vaccines
2. Myocarditis and pericarditis are inflammatory conditions affecting the heart muscles and the outer lining of the heart respectively. They occur more often in men compared to women. Patients present with symptoms such as chest pain, shortness of breath or abnormal heartbeats. 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. Myocarditis and pericarditis are separate and distinct conditions from heart attacks which are caused when blood flow to the heart is blocked.
3. Increased occurrences of myocarditis and pericarditis after the second dose of mRNA COVID-19 vaccinations have been observed overseas (Israel and the United States [US]) in adolescents and young men below the age of 25 years. The risk of this has been estimated to be 1.6 cases per 100,000 doses for mRNA vaccines in the US, which is comparable to the risk of anaphylaxis observed in Singapore. To date, there is no observed incremental risk of myocarditis and pericarditis after the first dose of vaccine.
4. Locally, the Health Sciences Authority (HSA) has reported 4 cases involving young men aged between 18 to 30 years. This is at the upper end of the expected range for this age group, based on background incidence rates. Most of the cases were reported to have occurred within a few days after receiving the second dose of the vaccine. All have recovered or have been discharged well from hospital.
Recommendations
5. While further studies and investigations are on-going, the currently available data suggests 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, EC19V recommends that vaccinated persons, in particular adolescents and younger men, should avoid strenuous physical activity for one week after their second dose. During this time, they should seek medical attention promptly if they develop chest pain, shortness of breath or abnormal heartbeats.
6. COVID-19 continues to be a health threat globally and in Singapore. The emergence of infectious variants can lead to widespread community COVID-19 transmission as well as the risk of severe COVID-19 disease and complications, including long term chronic complications. EC19V assesses that the benefits of the mRNA COVID-19 vaccinations continue to outweigh the known and potential risks.
7. EC19V will continue to monitor the available data as further analyses are conducted locally and internationally and will provide an update to the public.
EXPERT COMMITTEE ON COVID-19 VACCINATION
11 JUNE 2021