"Given the risks in the world around us and the uncertainty of the global rollout of the vaccine, we can expect our borders to be impacted for much of this year," Ardern said at a news conference.
For travel to restart, authorities either needed confidence that those vaccinated don't pass Covid-19 on to others, which is not yet known, or enough of the population needed to be vaccinated so people can safely re-enter New Zealand.
The first vaccines are due to arrive in New Zealand by the end of the first quarter, but the government wanted everything is in place in case of an earlier arrival.
Medical authorities, meanwhile, may approve a Covid-19 vaccine as early as next week, Ardern said, as pressure mounts for a start to vaccinations after the country confirmed its first case of the new coronavirus in the community in months.
A tough lockdown and geographical isolation helped the country of 5 million virtually eliminate the novel coronavirus within its borders.
New Zealand reported 2 new cases of Covid-19 at its managed isolation facilities on Tuesday and no new community cases. The country has 65 active cases, 1,934 confirmed cases in all, and 25 deaths.