Employers can bring workers into New Zealand via 2 border categories.
'Critical Health Worker' is an exemption category for those employed in the health sector in specific roles
'Other Critical Worker' is an exemption category for bringing employees over in any industry, government approved projects and scientific programmes. There is a very high threshold that employers need to meet to be approved under this section.
Due to the regularly changing requirements at the border, Immigration New Zealand website is the best source of information.