Myocarditis, pericarditis and the COVID-19 vaccine in New Zealand

An increased risk of heart inflammation (myocarditis, pericarditis, or both) has been observed in people who have received COVID-19 vaccines, particularly in males under 30 years of age after the second vaccine dose.

IMAC emphasises that the overwhelming benefits of vaccination in protecting against COVID-19 greatly outweigh the rare risk of these conditions, and Comirnaty (Pfizer mRNA vaccine) continues to be recommended for all people ≥ 5 years of age who do not have any contraindications to the vaccine.

For 1-3 days after vaccination, some people can feel unwell with headaches, tiredness, muscles aches, chills or a mild fever, this a normal response, and is more common after the second dose and in younger people. If unwell, you are advised to rest, drink plenty of fluids and to avoid vigorous exercise, until you are feeling better. If symptoms persist after a few days or worsen, to seek medical advice.

For further in-depth information for health practitioners, see our factsheet here.

Key points 

  • What are myocarditis and pericarditis? Can it occur after Pfizer (Comirnaty) vaccination? An increased risk of heart inflammation (myocarditis, pericarditis, or both) has been observed in people who have received some COVID-19 vaccines. Myocarditis occurs particularly in males under 30 years of age after the second vaccine dose of mRNA COVID-19 vaccines. Pericarditis is observed in a range of age groups, and has been reported following vaccination with Comirnaty and Nuvaxovid.
  • Can myocarditis or pericarditis occur after Nuvaxovid? Cases of myocarditis and pericarditis were identified in clinical trials of Nuvaxovid and have also been reported during post-authorisation use particularly in Australia. These findings suggest that an increased risk for these conditions may be present after receiving Nuvaxovid.
  • Myocarditis and pericarditis symptoms. A key symptom of myocarditis is chest pain. Other symptoms may include chest heaviness, discomfort or tightness, shortness breath or breathing difficulty, feeling lightheaded, faint or dizzy, heart palpitations, racing or fluttering heart, or a feeling of skipped beats. Fever has also been reported. One or more of these symptoms can occur shortly after vaccination due to stress or anxiety. However, if anyone experiences these symptoms after receiving a COVID-19 vaccine from more than 6 hours to 7 days (typically around 1 to 5 days), they should seek immediate medical attention.
  • The benefits of vaccination in protecting against COVID-19 greatly outweigh the risks of adverse events including myocarditis. Confirmed cases are rare.
  • Cases after vaccination are more frequently reported following the second dose and in males 12 to 29 years. Even in this group, risk has been reported internationally to be from 1 to 13 per 100,000 vaccine doses. There is increasing evidence that the rate declines as the interval between doses increases up to 8 weeks and the risk following booster doses is lower than after dose two.
  • How severe is myocarditis? Most reported cases of myocarditis and pericarditis, linked to mRNA vaccination, have required hospital care for assessment and monitoring, because sudden death is a rare complication of myocarditis (read more: what happens if a death occurs following immunisation). More than 80% of reported cases have recovered quickly with rest and commonly used oral medications. Longer-term follow-up of these cases is ongoing.

Advice about being vaccinated

Comirnaty (Pfizer mRNA vaccine) continues to be recommended for all people from 5 years of age. The only contraindication to the vaccine is anaphylaxis to a vaccine component which is very rare and requires specialist review.

If feeling unwell after vaccination, it is advised to rest, drink plenty of fluids and avoid vigorous activities, such as going to the gym. Seek medical advice if symptoms worsen, or persist for longer than 3 days.

All episodes of myocarditis and pericarditis following COVID vaccines should be reported to CARM.

For further advice and for plans for the patient’s next vaccination, please call 0800 IMMUNE (0800 466 863) or email [email protected]

Note: Adverse reactions to vaccines, including the COVID-19 vaccine may be covered by ACC as a treatment injury. Treatment injury does not cover ordinary consequences of vaccination. More information see ACC website here.


References

  • Gargano JW, Wallace M, Hadler SC, et al. Use of mRNA COVID-19 Vaccine After Reports of Myocarditis Among Vaccine Recipients: Update from the Advisory Committee on Immunization Practices - United States, June 2021. MMWR Morb Mortal Wkly Rep. 2021;70(27):977-82. doi: 10.15585/mmwr.mm7027e2
  • COVID-19 subcommittee of the WHO Global Advisory Committee on Vaccine Safety (GACVS): updated guidance regarding myocarditis and pericarditis reported with COVID-19 mRNA vaccines.   Retrieved 12 July 2021, from https://www.who.int/news/item/09-07-2021-gacvs-guidance-myocarditis-per…
  • Barda N, Dagan N, Ben‑Shlomo Y et al (2021) Safety of the BNT162b2 mRNA Covid-19     Vaccine in a Nationwide Setting DOI: 10.1056/NEJMoa2110475
  • Medsafe. Myocarditis and pericarditis – rare adverse reactions to Comirnaty (Pfizer COVID-19 vaccine). Alert Communication 21 July 2021. Retrieved 15 September 2021 from https://www.medsafe.govt.nz/safety/Alerts/comirnaty-myocarditis-alert.h…
  • Mevorach D, Anis E, Cedar N, et al. Myocarditis after BNT162b2 mRNA vaccine against COVID-19 in Israel. N Engl J Med. 2021;385(23):2140-9. doi: 10.1056/NEJMoa2109730
  • Buchan SA, Seo CY, Johnson C, et al. Epidemiology of myocarditis and pericarditis following mRNA vaccines in Ontario, Canada: by vaccine product, schedule and interval. medRxiv. 2021 (preprint):2021 doi: 10.1101/2021.12.02.21267156
  • Hause A, Baggs J, Marquez P, et al. Safety Monitoring of COVID-19 Vaccine Booster Doses Among Adults — United States, September 22, 2021–February 6, 2022. MMWR Morb Mortal Wkly Rep, 2022;71:249–254.

 

Last updated: 16 August 2022