Published: 20 December 2021

Safety Information

Alert communication

Reminder: Comirnaty vaccination (Pfizer COVID-19 vaccine) can cause myocarditis and pericarditis

20 December 2021

On 21 July 2021 we published an Alert Communication on the identification of myocarditis and pericarditis as a new but rare side effect of vaccination with Comirnaty vaccine (Pfizer COVID-19 vaccine). We are reminding everyone that myocarditis and pericarditis can occur after any dose of the Comirnaty vaccine, including after a booster dose. Children can also experience myocarditis and pericarditis after vaccination with Comirnaty. We have received reports for children aged 12 to 16 years.

Myocarditis also occurs after COVID-19 infection at a higher rate than after vaccination with Comirnaty1,2.

The benefits of vaccination with Comirnaty continue to outweigh the risk of experiencing a side effect for people of all ages in the approved indication.

Advice for consumers and caregivers

  • Myocarditis and pericarditis are treatable. Outcomes are better the sooner you start treatment.
  • In the first few days after your vaccination, seek urgent medical attention if you experience:
    • new-onset chest pain (or an increase in severity of existing chest pain), discomfort or heaviness
    • shortness of breath or difficulty breathing
    • an abnormal heartbeat or a racing fluttering feeling or a feeling of skipped heartbeats
    • dizziness, feeling lightheaded or fainting may also occur with the symptoms above.
    These are potential symptoms of myocarditis and pericarditis.
  • If you have children, please watch them for any decreased activity and actively question them about any symptoms. Children may not realise they have symptoms or may not talk about them without being asked.
  • Comirnaty COVID-19 vaccine is highly effective in protecting people from COVID-19 infection, which can also cause myocarditis.
  • If you think you or a member of your family has had a reaction to vaccination, please talk to your doctor. You can also report any adverse events following immunisation with COVID-19 vaccines to the Centre for Adverse Reactions Monitoring.

Advice for vaccinators

  • Myocarditis and pericarditis are rare adverse reactions to vaccination with Comirnaty vaccine.
  • Myocarditis and pericarditis are treatable, and recovery is better the sooner treatment starts.
  • You must tell everyone being vaccinated about the symptoms of myocarditis and pericarditis. Advise them to seek urgent medical attention if they experience any of the symptoms listed below.
  • Everyone should also be given a copy of the updated take home leaflet even if they have it before as this also gives them information on myocarditis and pericarditis.
  • Please advise parents and caregivers to watch their children for any decreased activity and actively question their children about any symptoms. Children may not realise they have symptoms or may not talk about them spontaneously.

Information for healthcare professionals

  • Myocarditis has been determined to be a rare side effect (about 30 cases per million vaccinations in New Zealand) to vaccination with Comirnaty. Be alert to the signs and symptoms of myocarditis and pericarditis occurring in people after vaccination.
  • Tell vaccinated individuals to seek urgent medical attention should they experience:
    • new-onset chest pain (or an increase in severity of existing chest pain), discomfort or heaviness
    • shortness of breath or difficulty breathing
    • an abnormal heartbeat or a racing fluttering feeling or a feeling of skipped heartbeats
    • dizziness, feeling lightheaded or fainting with the symptoms above.
  • Symptoms most commonly start in the first few days after vaccination (see figure 2 below).
  • Myocarditis and pericarditis are treatable, and outcomes are better the sooner that treatment is initiated.
  • Myocarditis associated with vaccination should be treated as other causes of myocarditis. Consult applicable guidance and/or secondary care (eg, cardiology or general medicine) if needed for more information on management. Advice has also been published in association with the Cardiac Society of Australia and New Zealand.
  • For advice on whether a subsequent dose of Comirnaty (eg booster doses) is appropriate for a patient under your care please contact the immunisation advisory centre (IMAC).
  • Please continue to report adverse events following immunisation with COVID-19 vaccines to CARM

Product affected

Product name Sponsor
Comirnaty Pfizer BioNTech

Further information

Myocarditis is inflammation of the heart muscle, while pericarditis is inflammation of the tissue forming a sac around the heart. Myo-pericarditis means that both the heart muscle and the sac are inflamed.

There are many possible causes of myocarditis, the most common being viral infection. New Zealand data from the Global Vaccine Data Network indicates that the background rate of myocarditis (pre COVID-19) in the overall population from 2011 to 2019 was 1.81 per 100,000 person-years.

Up to 1 December 2021, the Centre for Adverse Reactions Monitoring (CARM) has received 233 spontaneous reports of myocarditis, pericarditis or myopericarditis where the report contained evidence of a clinical diagnosis and the symptom onset time was within 30 days of vaccination (to reduce the risk of including coincidental cases). These reports do not necessarily have a causal relationship with administration of Comirnaty and may represent coincidental events. The age ranges, by dose number, are shown in Figure 1. The time to onset of symptoms, by dose number, is shown in Figure 2. Of the 233 reports, 58 percent were for males and 48 percent reported that the myocarditis/pericarditis was experienced after dose one.

Figure 1: Ages of people reported with myocarditis/pericarditis after Comirnaty vaccination* in New Zealand, by dose number, up to 1 December 2021

Note: 12 years is youngest age for a person reporting myocarditis after vaccination with Comirnaty.

10 year age group Dose 1 Dose 2
10 to 19 8 20
20 to 29 26 29
30 to 39 30 28
40 to 49 22 18
50 to 59 15 11
60 to 69 5 8
70 to 79 4 5
80 plus 2 2

Figure 2: Time to onset of symptoms of myocarditis/pericarditis after Comirnaty vaccination* in New Zealand, by dose number, up to 1 December 2021

Days Dose 1 Dose 2
0 26 36
1 19 23
2 15 16
3 8 10
4 9 1
5 6 4
6 6 2
7 0 4
8 3 0
9 2 1
10 2 1
11 0 0
12 0 3
13 0 2
14 1 1
15 2 1
16 2 1
17 1 2
18 2 0
19 1 0
20 plus 5 8

* These reports do not necessarily have a causal relationship with administration of Comirnaty and may represent coincidental events. Over 7 million doses have been administered.

References

  1. Boehmer TK, Kompaniyets L, Lavery AM, et al. Association Between COVID-19 and Myocarditis Using Hospital-Based Administrative Data — United States, March 2020–January 2021. MMWR Morb Mortal Wkly Rep 2 021;70:1228–1232. DOI: http://dx.doi.org/10.15585/mmwr.mm7035e5
  2. Barda N, Dagan,N, Ben-Shlomo Y et al Safety of the BNT162b2 mRNA Covid-19 vaccine in a nationwide setting Aug 25 2021 N Eng J med 385:1078-1090 DOI: 10.1056/NEJMoa2110475
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