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National | Novel Coronavirus / COVID-19

Covid-19 is more likely to cause myocarditis than the vaccine is

New Zealand has reported its first death linked to a rare side effect of the Pfizer vaccination. Here’s what we know about the risks of myocarditis after vaccination and after Covid-19 infection.

The death of a Kiwi woman following vaccination is tragic news.

While the coroner has yet to determine the cause of death, the Covid-19 Vaccine Independent Safety Monitoring Board considers she died from myocarditis, or inflammation of the heart muscle.

It's the first vaccine-linked death for a vaccination programme that has so far given 3.3 million doses of Pfizer vaccine.

Myocarditis, which can lead to chest pain, heart palpitations and shortness of breath, was recognised as a rare side effect of the Pfizer vaccine in July. A warning was also sent to doctors about similar condition pericarditis.

There have been 32 reports of myocarditis and pericarditis following vaccination in New Zealand. (That does not mean the vaccine necessarily caused the problem.)

It’s worth noting that myocarditis is much more common after Covid-19 infection than after vaccination.

Myocarditis can result from viral infections such as flu, and puts about 100 Kiwis in hospital every year.

In most Pfizer vaccine-related cases, the condition is mild and short-lived. Mostly reported in young men, it is estimated to affect less than one in a million vaccine recipients.

In this case, however, the monitoring board found myocarditis probably caused a woman’s death.

The board pointed out, however, that the woman also had other medical issues at the same time, which could have had a role to play.

That would be consistent with European reports of deaths from myocarditis following vaccination.

After administering 177 million doses of Pfizer, the European Medicines Agency identified 145 cases of myocarditis and 138 cases of pericarditis. Of the five people who died, all were either elderly or had other health problems.

The agency concluded that the cases occurred mainly within 14 days after vaccination, mostly after the second dose and in younger adult men.

A recent study of Israel data found the risk of suffering myocarditis after catching Covid-19 far outweighed the risk from vaccination. While vaccinated people were about three times more likely than the general population to get myocarditis, those who caught Covid-19 were 18 times more likely to develop it.

An American study found that was true even for those at highest risk of vaccine-related heart problems - young men. 

In 12-17-year-old boys, there were 450 myocarditis or pericarditis cases per million following Covid-19 infection, compared to about 77 cases per million following vaccination.

The authors concluded “considering all the risks and benefits of Covid-19 vaccination or just myocarditis, vaccination appears to be the safer choice for 12-19- year-old males and females”.

While the myocarditis death is New Zealand’s first vaccine-linked death, there have been other deaths following vaccination. To be clear, this does not mean they were caused by the vaccine.

As of 7 August 2021, there had been 26 New Zealand reports of people dying after having the jab.

Of those, 17 were unlikely to be related to the vaccine and four could not be assessed because there was not enough information. Five cases were still under investigation. It’s not yet clear if the woman who died is one of those five.

Nonetheless, experts continue to reiterate that the risks from Covid, which has already killed 26 Kiwis, far outweigh the risks of vaccination.

The Israel study pointed out that Covid infection also raised the risk of other serious health problems not associated with the vaccine, including acute kidney injury (125.4 extra events per 100,000 people), pulmonary embolism (61.7 events), deep-vein thrombosis (43.0 events), heart attack (25.1 events), and intracranial hemorrhage (7.6 events).

Reporting disclosure statement: This post was reviewed by The Whole Truth: Covid-19 Vaccination expert panel member Dr Maia Brewerton, a clinical immunologist, allergist and immunopathologist.