Several concerns need to be resolved before a trans-Tasman bubble can go ahead, but the government hopes on 6 April to announce a start date, Prime Minister Jacinda Ardern says.

Ardern has been speaking to media this afternoon after a Cabinet meeting.

She says 2020 was one of the most challenging years New Zealand has faced as a country. It will have been one year since we went into level 4 lockdown on Wednesday.

She says it is the government's intention that everyone in the country who can be vaccinated will be by the end of the year.

The vaccine will be "individual armour" and allows us to move our Covid-19 defences away from a "collective barricade", she says.

She says there are a series of concerns that must be resolved before a tran-Tasman bubble can be put in place.

She says she will meet with Cook Islands Prime Minister Mark Brown in Auckland on Thursday.

The National Party has been calling for a travel bubble with Australia and launched a petition to immediately start travel last week.

The plan is to have a safe travel zone between New Zealand and Australia in place by the end of April.

Ardern refused after last week's Cabinet meeting to give a firm date, but said the next step would be for a proposal to go to the full Cabinet, potentially this week.

However, she this morning again played down the significance of today's Cabinet meeting, saying a firm date was not likely to be announced.

Ardern said in May last year that September 2020 could be a "realistic" time frame for New Zealand's borders to open up to Australia.

However in October 2020, when the Australian government said it had finalised a deal for a limited travel bubble across the Tasman, Ardern said the country was still not ready for quarantine-free travel.

The government also confirmed its officials were prepared for a bubble in February, but Australia backed out and changed its position.