Dear member / clinic,

Advice from the Immunisation Advisory Centre is copied below, advising mycocarditis is a rare post-vaccination complication, seen 11 times more commonly with Covid than after vaccination.

Members may find the following additional information useful, particularly when consulting vaccine-hesitant patients.

Per US data, NZ can expect one presentation with vaccine-related myocarditis per 100,000 vaccinated, ie approx. 45 cases (likely there will also be subclinical cases), 80%+ male, generally younger, mainly after the second dose.

Pericarditis – 1.8/100,000, or around 80 cases presenting in New Zealand; older population; same male preponderance

Singapore government has advised:
that all vaccinated persons, in particular adolescents and younger men, who have received any dose of the mRNA COVID-19 vaccines, should avoid any exercise or strenuous physical activity for one week after vaccination. During this time, the vaccinated persons should seek medical attention promptly if they develop chest pain, shortness of breath or abnormal heartbeats. All doctors should also be vigilant around such clinical presentations after vaccination.”

We support informal advice from IMAC as follows:
“from a sensible pragmatic point of view and with limited evidence our advice would be to not vigorously exercise after receipt of a vaccine if you are feeling any vaccine side effects

Consulting vaccine hesitant patients concerned about adverse reactions:
  • United States studies find myocarditis is around 22 times more common with Covid19 (22/100,000) than after vaccination (1/100,000). This is in line with Israeli data cited below.
  • A recent BMJ study finds thrombotic events are again far more common with Covid than after vaccination – summarised below:


With best wishes,

David Gollogly, Jasmine Mackay, Richard Chen, Kelvin Ward
Pandemic Response Subcommittee

IMAC email:

Today the Ministry of Health issued a press release 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 COVID-19 Vaccine Independent Safety Monitoring Board (CV-ISMB) considered that the myocarditis was probably due to vaccination. The CV-ISMB noted that there were other medical issues occurring at the same time which may have influenced the outcome following vaccination.

Key points for vaccinators and other health professionals

  • A 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) used in New Zealand continues to be recommended for all people ≥ 12 years of age who do not have any contraindications to the vaccine.
  • Myocarditis symptoms such as chest pain, shortness of breath or feelings of having a fast-beating fluttering, or pounding heart may appear within a few days of having the vaccine. Anyone who experiences these symptoms after having the vaccine should seek medical attention.
  • Myocarditis or pericarditis reports have been more common following the second dose and in younger males.
  • The risk of myocarditis from COVID-19 infection is much greater than from COVID-19 vaccination: Recent data from Israel showed three cases of myocarditis per 100,000 following Comirnaty vaccination versus 11 per 100,000 with COVID-19 infection.
  • Most myocarditis and pericarditis cases linked to mRNA vaccination have required hospitalisation for assessment and monitoring but most cases have been mild and patients have recovered quickly with standard treatment. Longer-term follow-up of these cases is ongoing. However, sudden death may be a complication of myocarditis so careful assessment and management of suspected cases is important.
All episodes of myocarditis and pericarditis following Comirnaty should be notified to CARM.

More information about myocarditis and the COVID-19 vaccine in New Zealand is available on our website.

For further advice or support please call 0800 immune orā mihi,The Immunisation Advisory Centre