Director-General of Health Dr Ashley Bloomfield says vaccinated people may be able to self-isolate for a shorter period if they catch Covid-19.
It comes as Auckland's Covid-19 Delta variant oubreak grows and threatens to overwhelm contact tracing and isolation services.
Dr Bloomfield told Morning Report vaccinated people are likely to be infectious for a shorter period of time.
"They're less likely to pass on the virus, and if they are infectious they are infectious for a shorter period.
"Therefore, especially if they're asymptomatic, then they would only require a shorter period at home, whereas those who are unvaccinated, even if they don't have symptoms, are more likely to pass on the virus.
"They would need to remain isolated to avoid passing it on to others for a longer period."
The outbreak has overwhelmingly affected the unvaccinated, Dr Bloomfield said only 4 percent of cases were fully vaccinated.
"Some had a single vaccination, but the vast majority hadn't had one vaccine.
"Then if you look at hospitalizations, just three of I think around 170 hospitalizations were in people who are fully vaccinated, so it's highly protective."
Ministry of Health director of public health Dr Caroline McElnay said contact tracing services would be overwhelmed at around 160 or 170 new cases of the disease every day. Seventy-one new cases were announced on Thursday.
Dr Bloomfield said if that happened authorities would not stop contact tracing.
"We'd move to using a different range of processes for getting messages out to people who are contacts.
"Rather than them all being personally contacted we will be sending alerts out through the app. We might have businesses or other organisations where those contacts were just follow them up and make sure they were staying home and isolating.
"Of course our great hope is that as many of those contacts as possible are fully vaccinated, then their period of isolation is likely to be shorter and of course they will just have mild, if at all, any symptoms and be able to be looked after at home."
