New Zealand reported Monday that a woman had died after being inoculated with Pfizer's COVID-19 vaccine.
In an emailed statement by the Vaccine Independent Safety Monitoring Board on Monday, it said the woman died from myocarditis, a swelling of the heart muscle wall, after she received a Comirnaty Pfizer vaccine.
Myocarditis is known to be a rare side effect of the Pfizer vaccine, VISMB said.
There are many possible causes of myocarditis - the most common is viral infection. More than 100 people are hospitalized for myocarditis in New Zealand every year.
New Zealand's health officials said the number of new local infections had dropped to 53 on Monday.
There had been 83 new cases as of Sunday, which was the worst day of the Delta outbreak yet, and 82 the previous day.
New Zealand has seen 3,465 COVID-19 cases and 26 deaths so far, data by Johns Hopkins University show.
While the Center for Adverse Reactions Monitoring (CARM) has received other reports of fatalities in individuals recently immunized, none are considered tied to vaccination, the monitoring body disclosed.
Some clinicians warned of the risks of a rare side effect after the woman with other existing medical issues died after getting her jab.
Pfizer's media team in New Zealand didn't immediately respond to a request for comment.
So far the Pfizer-BioNTech, AstraZeneca and Janssen vaccines have been granted provisional approved by New Zealand's health officials. However, the Pfizer vaccine is the only one that has been authorized for distribution to the public.
Despite reports of adverse reaction to the Pfizer vaccine, independent authorities point out the approved shots remain generally safe for mass use.
The European Medicines Agency stated that the side effects were more common in younger males.
But EMA stressed the benefits of being immunized continue to far outweigh any risks, as vaccines help to prevent people from getting very ill with the virus.
New Zealand, which enforced a nationwide lockdown earlier this month, is trying to contain an outbreak of the Delta variant after almost six months of being disease-free.
More than 3.3 million shots of the Pfizer vaccine have been rolled out in New Zealand.
