Measures have been taken to protect New Zealand's Covid-19 immunisation programme amid reports of vaccine theft and sabotage overseas, the Ministry of Health says.

Doses of the vaccines developed in response to the pandemic which has killed 2.45 million worldwide are being offered for sale on hidden parts of the internet, although experts said many of the vaccines on the so-called dark web were likely fake or would never be shipped, the Financial Times reported.

And in Florida a man recently named "Paramedic of the Year" was arrested last month after helping a supervisor steal Covid-19 vaccines meant for first responders, police said.

There's also been instances of sabotage, with Wisconsin pharmacist and self-proclaimed conspiracy theorist Stephen Brandenburg now facing up to 20 years in prison after he admitted tampering with more than 500 doses of coronavirus vaccine.

They were aware of incidents overseas of vaccine theft and sabotage, a Ministry of Health spokeswoman told the Herald.

"Vaccine security is an important priority and this is even more critical with the high-profile nature of the Covid-19 vaccine."

The ministry were taking "all steps possible" to protect the safety of New Zealand's Covid-19 immunisation programme, which officially begins today with border and MIQ workers lining up for their first Pfizer-BioNTech jab.

"We're taking all steps possible to protect the safety of our Covid-19 immunisation programme here in New Zealand.

"At this stage, we wish to withhold details about the vaccines' storage locations and transport around New Zealand, including the companies involved in this work."