Visa conditions for people employed in essential services have been relaxed even more. Please go through the changes found on the immigration New Zealand Covid-19 response page.
These changes are mainly for workers and international students employed in essential services. At this hour we can use all the help we can get to meet the needs of the country, a great step to show that New Zealand cares for its migrant population and how pivotal they are to fight this pandemic.
Here is the link to what can be considered as essential services at level 3 and 4.