Wellington, New Zealand - New Zealand health authorities have launched an investigation after a man allegedly got vaccinated against Covid-19 up to 10 times in one day, local media reported.

It is thought the man was paid for the jabs on behalf of other people, news website Stuff reported on Saturday.

The country's Ministry of Health was taking the matter seriously, Covid-19 vaccine and immunization program manager Astrid Koornneef told Stuff.

"We are very concerned about this situation and are working with the appropriate agencies," she said.

"Having an inaccurate vaccination status not only puts you at risk, it puts your friends, whanau [family] and community at risk, and the healthcare teams that treat you now in the future," she said.

Auckland University professor Nikki Turner was quoted as saying there was no way to know for certain what effects this kind of vaccine load would have on someone.

In New Zealand, people do not have to show identification when receiving the vaccine. Many of the country's businesses and facilities use a domestic vaccination certificate that only allows fully vaccinated people access to places.

About 89% of New Zealand residents are fully vaccinated. With a population of 5 million, the country has reported about 12,500 cases of Covid-19 and 46 deaths since the onset of the pandemic.