New Zealand authorities have said they had linked a 26-year-old man's death to Pfizer Inc's Covid-19 vaccine after the person suffered myocarditis, a rare inflammation of the heart muscle, after taking his first dose.

“With the current available information, the board has considered that the myocarditis was probably due to vaccination in this individual,” a Covid-19 Vaccine Independent Safety Monitoring Board said in a statement, Reuters reported.

The man, who died within two weeks of his first dose, had not sought medical advice or treatment for his symptoms. Myocarditis is an inflammation of the heart muscle that can limit the organ's ability to pump blood and can cause changes in heartbeat rhythms.