Wellington, where Avatar 2 is filming, has been able to continue moving forward with production as the city has only been graded at a Level 2 concern. Currently Level 2 means gatherings up to 100 people are OK. Though the Avatar productions are more involved than that, as long as people are social distancing, per Variety, production is able to move forward with safety precautions in place.
Article source: https://www.cinemablend.com/news/2552437/whats-going-on-with-avatar-and-other-hollywood-productions-as-new-zealand-covid-19-spikes