Dozens of children are battling a highly contagious winter virus in intensive care units around the country.

Eleven of the country's 20 district health boards today told the Herald 22 children were currently being cared for in intensive care or high dependency units with respiratory syncytial virus (RSV) or respiratory-type illnesses.

Auckland's Starship Hospital, New Zealand's largest children's hospital, said it could not provide figures today as staff were "focused on the operational response". Counties Manukau and Canterbury DHBs said they would not provide figures for the number of children in intensive care.

Wellington Regional Hospital today had another 26 children in the wards with RSV and respiratory-type illnesses who did not need to be in intensive care while Hutt Hospital had 13.

The Ministry of Health explained that not all patients were tested for RSV because confirmation of the virus did not change the care given by hospital staff.

The Ministry confirmed there had been a surge in respiratory viral infections which was stretching hospital capacity but said district health boards had told them they had plans in place to meet the extra demand.

Earlier this week hospitals across the country reported postponing surgeries and creating extra bed space for children as they dealt with a sharp surge of RSV.

Children, babies in particular, were being hit particularly hard by it this year with many ending up in intensive care units or needing oxygen to help them breathe.

Some parents described calling for an ambulance after their child's temperature spiked to dangerous levels or as they struggled to breathe as a result of the virus.

ESR (Institute of Environmental Science and Research) data showed weekly visits to our six main hospitals for RSV had more than doubled in the last week, from 204 to 538 presentations. Only 34 cases were recorded between April to September last year.

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To date, 969 RSV cases have been reported in just five weeks by ESR's laboratory network, compared with an annual average of 1743 cases during the winter period reported in the five years before Covid-19.

DHBs are now doing everything they can to cater for the spike, including postponing surgeries, creating extra beds, increasing staffing, bringing in help from other parts of the hospital and restricting visitors.

Auckland DHB director of provider services Dr Mike Shepherd said they were doing all that as Starship's emergency department continued to see record numbers of children - many with winter respiratory illnesses.

To prevent the spread of infection within the hospital only parents and caregivers could visit patients in Starship. Children under 14 were also unable to visit maternity and gynaecology wards or outpatient clinics at Auckland City Hospital and Greenlane Clinical Centre, he said.

At Middlemore Hospital a playroom had been converted into a clinical space with 11 special care baby cots to help combat the demand.

Dr Sue Huang - a virologist who tracks flu-like illnesses - said since New Zealand opened our bubble to Australia there had been a sharp increase in the number of RSV hospital presentations.

"The week we opened the bubble we had one presentation of RSV and it's been increasing ever since," Huang said.

Earlier in the week Starship general paediatrician Professor Cameron Grant told Newstalk ZB's Heather Du Plessis-Allan that babies born in New Zealand last year didn't get exposed to RSV because of lockdown and our borders staying closed.

"Those babies are seeing RSV for the first time this year as are all the babies that are being born this year. So we have twice as many babies having their first infection, hence getting really sick with this infection," Grant said.

Number of children in hospital intensive care units on the afternoon of July 9 with RSV or respiratory-type illnesses

• Northland - 0
• Auckland (Starship) - Unable to provide figures
• Counties Manukau - Unable to provide figures
• Waitemata - Children sent to Starship if they needed NICU or PICU care
• Waikato - 5
• Lakes - 2
• Tairawhiti - 2
• Taranaki - 3
• Hawkes Bay - 4
• Capital and Coast - 4
• Hutt Valley - none
• Nelson Marlborough - 0
• Wairarapa - 2
• Canterbury - Unable to provide figures
• Southern - 0

What is RSV?

• Respiratory syncytial virus (RSV) causes infections of the lungs and respiratory tract.
• It's so common that most children have been infected with the virus by age 2, but it can also infect adults.
• Symptoms are usually mild and typically mimic a common cold but they cause a severe infection in babies - especially premature infants and elderly or those with weak immune systems.