An independent vaccine safety monitoring board said the woman’s death was “probably” due to myocarditis, an inflammation of the heart muscle.
It also noted there were other medical issues which could have “influenced the outcome following vaccination”.
European regulators say myocarditis is a “very rare” side effect and that the vaccine’s benefits outweigh the risks.
The official cause of death has not yet been determined.
However, the Covid-19 Vaccine Independent Safety Monitoring Board said the myocarditis was “probably due to vaccination”.
“This is the first case in New Zealand where a death in the days following vaccination has been linked to the Pfizer COVID-19 vaccine. While the Centre for Adverse Reactions Monitoring has received other reports of deaths in someone recently vaccinated, none are considered related to vaccination,” it said in a statement.
The woman’s death is being investigated further and a coroner is due to rule on the case. Officials have not released any further details, including the woman’s age.
The European Medicines Agency has highlighted myocarditis as a “very rare” side effect of the Covid vaccines made by Pfizer and Moderna, adding that the side-effects were more common in younger men.
For instance, the UK has seen 195 reports of myocarditis among people who have received the Pfizer vaccine, at a rate of around five cases per million. Most of those cases have led to mild symptoms.
The EMA has urged people to continue to get vaccinated, as they help to stop people from getting very sick with Covid-19.
Symptoms of myocarditis can include new onset chest pain, shortness of breath and an abnormal heartbeat.
Experts are urging anyone experiencing these symptoms in the days after vaccination to seek medical attention promptly.
On Monday New Zealand officials said they “remain confident about using [the Pfizer vaccine] in New Zealand”.
According to Johns Hopkins University, the country has seen 3,465 Covid cases and 26 deaths so far.
New Zealand was initially praised for its handling of the virus, but has since seen a slow roll-out of vaccines although it has been ramping up in recent days.
More than three million vaccine doses have been administered, and 23% of the population are now fully vaccinated.
A recent spike in Covid cases, attributed to the Delta variant, has put large parts of the country into lockdown. There are currently more than 560 cases in the country of about 5 million people.
Restrictions are set to ease on Tuesday, barring the country’s biggest city Auckland.