A healthy 13-year-old who unexpectedly died 10 days after receiving a vaccination against Covid-19 had a “microscopic” amount of myocarditis in a crucial part of his heart.  

A coroner said the myocarditis - inflammation of the heart muscle - could have been caused by viruses found in the Wellington boy’s heart tissue, but due to the short period of time since his immunisation, the vaccine could not be ruled out as a possible cause. 

The coroner released a report into the teenager’s tragic death this morning, finding while the myocarditis caused his sudden death, he could not satisfactorily determine what caused the myocarditis. 

The boy, whose name and identifying details have been suppressed, died in October 2021. 

He was a fit, healthy and active child who had no significant medical issues and did not take any medication, Coroner Robin Kay said in his report. 

On the night of his death, he came home from school and spent a normal evening doing chores, eating dinner, playing cards with his mother and watching a movie in the lounge. 

He went to bed about 8.30pm, telling his mother he felt warm and getting a drink of water. 

His parents did not see him again that night, and when his father went to check on him just before 7.30am, noticing he hadn’t got up, he found him face-down on the bed, rigid. 

The boy’s father started CPR, but when emergency responders arrived they did not continue it. He was pronounced dead at the scene. 

Testing done after the boy’s death showed a “microscopic” amount of myocarditis in his heart affecting nodes which stimulate the heart to beat. 

Evidence of other viruses that may be able to cause myocarditis were found in his heart tissue, but the fact he had received a Covid-19 vaccination 10 days prior complicated matters. 

“One of the pathologists commented that had [he] not died 10 days following a Covid-19 mRNA vaccination, the presence of inflammation in his heart and the detection of the viral DNA in his heart tissue from viruses known to cause myocarditis ‘mean that the cause of death would have been confidently provided as viral myocarditis’,” the report said. 

Pfizer's mRNA shot has been New Zealand's Covid vaccine of choice. Photo / Sylvie Whinray 

Myocarditis can occur due to viral infections of the heart or as an autoimmune reaction following a viral infection. 

“[The boy] was extremely unfortunate that the microscopic amount of myocarditis in his heart was located in parts that are involved in the creation and passage of electrical signals that make the heartbeat. Had that myocarditis been present somewhere else in [his] heart, the expert evidence is that it would not have caused his death (and he may not have noticed any symptoms or exhibited any signs).” 

Research has shown an increased risk of myocarditis in overseas studies of people receiving Covid-19 mRNA vaccines, particularly in males under 30 years of age after the second vaccine dose. Covid itself has also been shown to cause myocarditis at a much higher rate than the vaccine. 

Most of the studies reported no deaths due to myocarditis and the majority of cases were considered mild, not requiring treatment. 

Paramedics were called but the boy was pronounced dead at the scene. 

A forensic pathologist examining the boy’s case noted the microscopic appearance of the myocarditis was different to fatal cases that had been linked to the vaccine in literature and in New Zealand cases. 

“The [pathologist’s] report identifies that this is a complicated case where death was caused by a tiny amount of inflammation that unfortunately occurred in a crucial part of [the boy’s] heart, and that there were two major risk factors for this – a recent Covid-19 vaccination and viruses known to cause myocarditis in the tested tissue. 

“Although the presence of myocarditis and the detection of viruses known to cause myocarditis suggests, but does not prove, a viral cause; the Covid-19 vaccination given 10 days before [he] died cannot be definitively excluded as causing or contributing to the myocarditis.” 

Kay said there were several possible causes for the boy’s death. 

It could have been caused by the viruses in his heart or the vaccine. The vaccine and the viruses could also have interacted in some way that it caused myocarditis when it otherwise would not have. 

It was also possible neither the viruses nor the vaccine had anything to do with his death “and the inflammation instead resulted by something entirely different that cannot be identified with current medical knowledge”. 

“Sadly, despite the amount of expert evidence that has been obtained it has not been possible to identify the cause of the myocarditis in [the boy’s] heart.” 

This article was originally published on the NZ Herald here.