The number of nasty winter bugs in Waikato has dramatically increased in recent weeks, with sick children packing Waikato Hospital's children's ward.

Flu cases have tripled in the past month, according to the district health board's respiratory virus report.

And the children's ward has been full all week with youngsters presenting with RSV (respiratory syncytial virus).

Charge nurse Betsy Smith said there were 24 children in the ward yesterday morning presenting with RSV-type symptoms.

"Some children are staying anything from four to five days," she said.

Whooping cough was also on the increase.

The hospital had managed to free up six beds to allow for weekend demand, but Ms Smith urged people with "snotty noses" who were "coughing and spluttering" to stay away from young children - especially those under 2.

"Little people just don't have the coping mechanisms that adults or even older children do," she said.

Waikato District Health Board medical officer of health Dr Anita Bell said both influenza A and RSV had shown up in higher numbers in their lab tests over the past weeks.

Tests had shown a jump from 10 cases of flu in the week July 16 to 22, to 25 cases during August 6 to 12. RSV had remained constant during the same period at around 22 cases a week.

That compared to no cases of flu showing up in tests at the beginning of June.

Dr Bell said they had managed to avoid too many cases of norovirus.

The good news was the strains of flu they were seeing were covered by the flu vaccine.

Yesterday, Health Minister Tony Ryall announced that over one million Kiwis got the flu jab this season.

"This is the second time we have reached this milestone - the other was in 2010, the second year of the swine flu pandemic, when around 1.02 million New Zealanders had a flu vaccination."

Last year about 990,000 doses were distributed.

Watch the effects of whooping cough on a baby at waikatodhb.govt.nz/page/pageid/2145839762/Whooping-Cough

- © Fairfax NZ News