The winter flu season was one of the mildest in the past two decades, but experts warn that is no reason for complacency.
Figures from the surveillance programme SHIVERS show influenza hospitalisation rates were down significantly from 2012, as were deaths from severe acute respiratory infections.
Director of the Immunisation Advisory Centre and project co-leader Dr Nikki Turner says this year's vaccine was a very good match with the circulating flu strain.
She says there was also some community immunity from previous exposure to it.
"We can not guarantee the same next year, so we certainly have to keep up our high vaccination rates and we certainly have to warn people that the flu will always be with us, and every year we have to think about it."
She says the study has all kinds of uses, like helping improve strategies.
"We certainly need to look at issues around poverty in New Zealand, and why poverty in particular drives diseases.
"As well as all the effects like poor housing, crowding, transmission of diseases, poor nutrition. The things that are really driving disease rates and poverty."
Nikki Turner says the findings will be passed on to Northern Hemisphere colleagues to help them prepare for their winter flu season.