Mild myocarditis reported with COVID-19 mRNA vaccines

Mild myocarditis reported with COVID-19 mRNA vaccines
© iStock-Wasan Tita

Cases of mild myocarditis are being reported in people who have been vaccinated with the COVID-19 mRNA vaccines.

Myocarditis is an inflammation of the heart muscle and pericarditis is an inflammation of the lining that surrounds the heart. The condition can cause serious illness, however, often it is mild and responds well to treatment. The World Health Organization (WHO) Global Advisory Committee on Vaccine Safety (GACVS) COVID-19 subcommittee is now reviewing the small number of reports relating to the cases, and has noted that, in most of the cases, the individuals have recovered.

The subcommittee is soliciting and monitoring for additional information to assess for any relationship to COVID-19 vaccination.

Adolescents and young adults

The US Advisory Committee on Immunization Practices (ACIP) COVID-19 Vaccine Safety Technical (VaST) Work Group has said that there are currently few reports of myocarditis and that the cases seem to be occurring predominantly in male adolescents and young adults. The cases are also occurring more commonly after the second dose of the vaccine, within four days after receiving it.

However, it has also been highlighted that most of these cases appeared to be mild and follow up is ongoing.

The GACVS subcommittee noted that most of the information received so far is based on spontaneous, passive reporting, and that more rigorous studies using alternative data sources and more robust study designs are needed to assess a potential causal association between the event and the vaccine.

Reviewing the data

Countries such as Israel, the United Kingdom, and the United States have embarked upon such studies. The GACVS subcommittee will review further as more data become available, and a draft case definition for myocarditis has been developed recently by the Brighton Collaboration.

The subcommittee is now encouraging all health professionals to report all events of myocarditis and other adverse events observed with these and other vaccines.

The GACVS COVID-19 subcommittee will continue to review the safety data from all COVID-19 vaccines and update any advice as necessary, and the WHO is carefully monitoring the rollout of all COVID-19 vaccines.

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