New Zealand now has two deals in place to supply millions of doses of COVID-19 vaccine to Kiwis.

New Zealand has agreed a deal to buy up to five million doses of COVID-19 vaccine from Janssen Pharmaceutica, which if realised would see every New Zealander receive a vaccine by 2022.

Science Minister Megan Woods announced on Thursday an in-principle agreement with the Belgian company, owned by US giants Johnson & Johnson.

"We expect a formal advance purchase agreement to be finalised in coming weeks," Ms Woods said.

She said New Zealand, like Australia, was taking a "portfolio approach" to buying vaccine, aiming to access a range of options.

The government has already agreed a deal with Pfizer to supply vaccine for 750,000 people, which the government hopes to have available in the first half of 2021.

The deal with Janssen would see up to two million doses available later in 2021, with an option for three million more in 2022.

Also on Thursday, New Zealand began a new regime for protecting against the deadly virus in the community.

Aucklanders are being required to wear masks on public transport, as is everyone catching a flight in New Zealand.

The move is a response to another virus case slipping out of the country's border regime, at least the seventh in the past four months.