Prime Minister Jacinda Ardern denies using fear as a motivator for people to get vaccinated.
Former prime minister Sir John Key, has written editorials calling for financial incentives instead of fear tactics to increase vaccination numbers.
He described New Zealand as a "smug hermit kingdom".
Ardern told Morning Report the government had been making policy based on the best evidence and released information behind its decision-making.
She said fear had never been a "strategy".
"So just making sure that people know that our researchers and evidence overseas is telling us that a high vaccination rate doesn't stop outbreaks.
"I think there may be an assumption that once vaccinated Delta disappears and unfortunately no country has seen that."
Ardern said several countries had border restrictions despite having large numbers of vaccinated citizens.
"Many countries are in an experimental phase now that they are vaccinated, and are operating cautiously.
"We have talked about our reopening plan, we are, for instance, this year trialling self-isolation as a pilot so that we have more options for people to isolate at home.
"We've talked in the new year, once we have a vaccinated population, [of] easing our border restrictions using shortened isolation periods."
She said that was part of the plan for reopening New Zealand's borders, "but of course we need more people vaccinated at the moment".
Officials have been working on a health pass system, which is expected to be rolled out in the next month.
RNZ understands it is legally difficult to make Covid-19 vaccination certificates mandatory in places like restaurants and bars.
But Ardern said allowing the events sector to use them was being considered.
She said it would be used in "more high-risk environments rather than the ability to access essential services".