Research Highlights:

  • New analysis indicates the benefits of the COVID-19 vaccine outweigh the risks of developing myocarditis, a rare heart condition that has been reported at a higher prevalence than expected among some people who received either the Pfizer or Moderna COVID mRNA vaccine.
  • Researchers reviewed data from U.S. Centers of Disease Control and Prevention’s Vaccine Adverse Event Reporting System (VAERS) and from studies recently published to assess rates of COVID-19 vaccination compared with rates of suspected myocarditis after receiving a COVID-19 mRNA vaccine.
  • An analysis of the potential prevention of COVID-19 as a result of the COVID-19 vaccine was also conducted comparing the rate of suspected myocarditis to the prevention of COVID-19, COVID-19-associated hospitalization, ICU admission and death. The benefit-risk assessment indicates that the benefits of the COVID-19 vaccine outweigh the risk of myocarditis. 
  • Some of the clinical mechanisms that may be driving the increased rates of myocarditis were evaluated, and more research is recommended.

DALLAS, July 20, 2021 — The benefits of the COVID-19 vaccine outweigh the low risk of developing myocarditis after receiving the COVID-19 vaccine, according to research published today in Circulation, the flagship journal of the American Heart Association

Last month, the U.S. Centers for Disease Control and Prevention (CDC) identified a “likely association” between the two COVID-19 mRNA vaccines, from Pfizer-BioNTech and Moderna, and cases of suspected myocarditis and pericarditis. Most of the suspected cases of myocarditis developed after the second dose of a COVID-19 vaccine and were among younger males (between the ages of 12-39 years).

Researchers conducted an analysis of data from the CDC’s Vaccine Adverse Event Reporting System (VAERS) and from multiple peer-reviewed scientific journal articles to compare vaccination rates to reports of myocarditis among people who received the COVID-19 vaccine through mid-June 2021. The analysis found:

  • Most people suspected to have myocarditis presented with chest pain, usually 2-3 days after a second dose of a COVID-19 mRNA vaccination.
  • Some people suspected to have myocarditis experienced fever and muscle pain the day after their vaccination.
  • Those affected and requiring hospitalization for suspected myocarditis were mostly young males (ages 12-19) without a prior history of COVID-19 or other health conditions.
  • All tested negative for COVID-19.
  • Most patients were discharged from the hospital as their symptoms, diagnostic and imaging signs of the condition returned to normal, either with or without treatment.

According to the CDC data pulled by the researchers for this report, as of June 23, 2021, more than 177 million people in the U.S. had received at least one dose of a COVID-19 vaccine. The rates of suspected myocarditis/pericarditis were approximately 12.6 cases per million doses of the second dose of a COVID-19 mRNA vaccine among 12–39 year-olds as of June 5, 2021, according to data from the CDC’s Vaccine Safety Dataline.

The researchers also conducted a prevention analysis by comparing the rate of suspected myocarditis to the prevention of COVID-19, COVID-19-associated hospitalization, COVID-19 ICU admission and COVID-19-related death. The benefit-risk assessment indicates that the benefits of the COVID-19 vaccine outweigh the risk of myocarditis. The research group concluded:

  • There is a “known potential risk of complications with COVID-19 infection, including hospitalizations and death, even in younger adults (mortality remains 0.1-1 per 100,000 for persons aged 12-29 years);
  • The risk-benefit decision remains overwhelmingly favorable for vaccination; therefore COVID-19 vaccination is currently recommended for everyone 12 years of age and older.
  • COVID-19 vaccination not only prevents COVID-19-related hospitalizations and death, but also COVID-19 related complications such as myocarditis, multisystem inflammatory syndrome (MIS) and post-acute sequelae (i.e., consequences) of SARS-CoV-2 infection or long COVID-19.”

The researchers recommend that clinicians should be aware of the potential for myocarditis and pericarditis, which should be considered in individuals presenting with chest pain within a week after receiving a COVID-19 vaccine, especially among adolescents, teens and young adults.

Further analysis of this study investigated some of the possible clinical mechanisms causing myocarditis after COVID-19 vaccination, however, the authors noted more research is needed.

Authors are Biykem Bozkurt, M.D., Ph.D.; Ishan Kamat, M.D.; and Peter J. Hotez, M.D., Ph.D. Author disclosures are in the manuscript. There was no funding reported for this study.

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