A study has revealed the number of patients admitted to intensive care in Auckland with severe flu symptoms has doubled compared to last year.
Findings from the study show 109 people were admitted to intensive care in the region during the 2014 influenza season, compared with 52 in 2013.
The study, conducted in Auckland for the US Centers for Disease Control (CDC), showed infants aged under 1 were almost five times as likely to be admitted to hospital as the next hardest-hit group, those aged 1 to 4.
Four patients died from this year's most predominant winter flu strain compared to none in 2013.
One of the specialists taking part in the study, Nikki Turner of the University of Auckland, said the research showed New Zealand needed to focus on the strategy for raising awareness of flu vaccinations among pregnant women.
She said the study revealed young children have a high burden of the disease.
"There's some challenges with that. Vaccines can only be used from six months of age so you've got a very vulnerable period for infants under six months of age and that highlights the importance of focussing on pregnancy vaccinations.
"If you vaccinate a pregnant woman she will pass passive protection to infant that will give the infant a high degree of protection.
While the study was conducted in Auckland, Dr Turner believed the figures could be extrapolated over the country.