Myocarditis 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 mRNA COVID-19 vaccines in overseas studies, 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 ≥ 12 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 

  • Following a press release issued by the Ministry of Health on 30 August regarding the death of a woman in the days following vaccination with the Pfizer COVID-19 vaccine, the Ministry of Health states the case has been referred to the Coroner and the cause of death has not yet been determined. The CV-ISMB considered that the myocarditis was probably due to vaccination but noted that there were other medical issues occurring at the same time which may have influenced the outcome following vaccination.
  • 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 mRNA COVID-19 vaccines in overseas studies, particularly in males under 30 years of age after the second vaccine dose.
  • Myocarditis and pericarditis symptoms include chest pain, feelings of having a fast-beating, fluttering or pounding heart and shortness of breath. One or more of these symptoms can occur shortly after vaccination due to stress or anxiety. However, if anyone experiences these symptoms after receiving Comirnaty (Pfizer mRNA 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. The risk of myocarditis from COVID-19 infection is almost four times higher than from vaccination. Confirmed cases are rare.
  • Cases after vaccination are more frequently reported following the second dose and in males 12 to 30 years. Even in this group, risk is less than 1 in 25,000 vaccine recipients.
  • 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 8 out of 10 of the reported cases have recovered quickly with rest and commonly used oral anti-inflammatory medications such as ibuprofen. 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 12 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 Comirnaty 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]


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…

Webinar replay: The mRNA COVID-19 vaccine in NZ: understanding variants and safety signals including myocarditis

20 July 2021: This webinar covers vaccine effectiveness with COVID-19 variants and current information around vaccine safety.

Presenters: Dr Joan Ingram & Dr Peter McIntyre, Medical Advisors for the Immunisation Advisory Centre

Additional resources:

Last updated: 01 October 2021