Influenza contributes to the death of 400 New Zealanders each year, according to researchers at the University of Otago.
The study examined influenza-associated death from 1990 until 2008 and found that 86 percent of deaths occurred in people aged 65 and over.
Co-author Professor Michael Baker said most people do not die directly from influenza, but it could trigger or worsen other conditions such as pneumonia and heart attack, which is why the elderly especially are vulnerable.
The study found that the mortality rate of those with influenza did not show any downward trend over the 18-year period.
Professor Baker said influenza is New Zealand's biggest infectious disease killer, and advises the elderly and sick to receive free vaccinations available.
