Extra paediatricians are being drafted in and elective procedures are still being called off in the busiest flu season for Auckland's children's hospitals in years.

PHF Science figures showed there had been about 70 children with the most severe respiratory symptoms admitted each week for the past four weeks to Kidz First and Starship hospitals.

That was an 85% increase since the end of July and did not reflect the total number of children in hospital with respiratory symptoms, or emergency presentations.

South Auckland paediatrician Dame Teuila Percival said this winter had been the worst for years - and the busiest she could remember.

It had been all hands on deck at KidzFirst.

"People do extra shifts, we have senior medical officers like myself, and others who work in places like psychiatry coming in, helping out doing more time in the ED," Dame Teuila said.

Children were being admitted with a wide range of symptoms including dehydration, confusion from fever, vomiting, diarrhoea, difficulty breathing, a bad cough and needing oxygen, she said.

Some were in intensive care - usually because they needed high levels of support with breathing, she said.

"They're taken care of very well when they're there but its very stressful for parents and families to see their children so unwell," he said.

RNZ understands Starship also remained very busy, with elective procedures still regularly deferred because the space was need for acutely unwell children.

More help needed next year

Dame Teuila said many of the sickest children were Pasifika or Māori.

It was great that the flu vaccine had been made free for children aged under five years old earlier this month, but said she would like to see it free for everyone next winter.

Flu often made its way around a family, and more vaccination would help.

"It's not uncommon that the whole family come to ED - and we see all the children and the mum and the dad and everybody's sick.”

Dame Teuila said there needed to be more resources for general practice to be able to help more people get in to see their doctors before they got worse.

"I do think getting to primary care is a barrier for a lot of families particularly if you have got two, three, four kids all sick. Its very hard to get into see someone at the moment in a timely way.

"My colleagues in primary care work really hard. They're just under the pump when I speak to them on the phone as we all are. They just need more people.”

RNZ asked Health NZ for figures for children in other main hospitals in the country, but it said they needed to go through the Official Information Act process - which could take several weeks.

PHF Science kept combined figures for the two dedicated children's hospitals in Auckland, which is why they were readily available.

A spokesperson said the figures which went to September 6 were part of its severe acute respiratory surveillance which only covered some of the sickest children.

Other respiratory hospitalisations would not be included.