From this Friday, gatherings can be attended by up to 100 people, and the Director-General of Health is confident contact tracing is ready, if needed.
Dr Ashley Bloomfield told Morning Report tracing that number of people could be done "very quickly".
"As long as we have got their contact details, and this is the key issue that we need to encourage people to do, is by using the ministry's (contact tracing) app."
He said data from mid April to mid May showed 82 percent of people could be contact traced within two days.
But the aim, with events of up to 100 people, would be to trace all people within two days of a case being confirmed.
"We not only could do that, but we are doing that. And this is a key point, even at a private function like a wedding, or if you are having a group of people at home ... you still want to look after them, and keeping a record of who's been there, it's not too much trouble, but that is the critical thing that will help us trace people quickly."
He was "optimistic" that there was no community transmission in New Zealand.
"Our elimination approach is ongoing ... because a key pillar of it is of course our really strong border measures and obviously they continue because we want to prevent any further cases coming into the country or if one does sneak through, we want to be able to find it and stamp it out really quickly."
He said the two-week quarantine was still the gold standard being used around the world.
"The thing here is that we are finding people that are still testing positive some weeks after their initial symptoms but what seems to becoming clear ... is that they are not actually infectious."
The low number of cases occurring while testing continued was "very encouraging", he said.
Read more about the Covid-19 coronavirus:
- See all RNZ Covid-19 news
- Covid-19 symptoms: What they are and how they make you feel
- Touching your Face: Why do we do it and how to stop
- Scientific hand-washing advice to avoid infection
- Your Covid-19 questions answered - from health and employment to managing anxiety
- A timeline: How the coronavirus started, spread and stalled life in New Zealand
- Coronavirus: A glossary of terms
- The Coronavirus Podcast