An "older adult" has died in Tauranga after catching RSV, as cases of the respiratory illness see hundreds turning up to hospital.
The cause of the adult's death was attributed to numerous underlying medical conditions, the Bay of Plenty District Health Board said.
Since the beginning of the outbreak in May, Tauranga Hospital has seen hundreds of people with the virus, with 16 ending up in intensive care - 13 of them children.
The DHB said 270 cases had either been seen through the emergency department or admitted to the hospital since the first case on May 25.
This is more than double the 107 cases in the same period in 2019, and more than the total 216 for the full 2019 year.
It comes as children across the country are being admitted to intensive care with RSV, prompting some hospitals to restrict guests to the ward and others to postpone elective surgeries because of the outbreak.
Earlier this week the NZ Herald reported a 63-year-old Auckland woman had died after contracting the virus.
Bay of Plenty DHB clinical nurse specialist infection prevention and control Robyn Boyne said cases in Tauranga had escalated since June 20.
The emergency department and paediatric ward had been hit the hardest, with the majority of patients in those wards being treated for RSV.
The children's ward had employed its Paediatric Variance Response Plan, which Boyne said was done at times of high demand.
She said swing beds in the adjacent ward could be used to increase capacity so the ward with the greatest need could safely use them.
This year, 13 children and three adults have been admitted to the Intensive Care Unit as a result of RSV.
Boyne said one "older adult" who had the virus died but their cause of death was attributable to numerous underlying medical conditions.
The DHB would not release further information about the person, including when they died, on privacy grounds.
A Pāpāmoa mum has spoken of the rough days after her 22-month-old caught RSV and end up in hospital this week, relying on a feeding tube and intermittent oxygen.
The woman, who asked to be anonymous to protect her daughter's privacy, said the virus took control of the little girl "pretty fast".
"She was fine on Friday and then Saturday morning she was a little off but Sunday she was not herself at all."
Snotty, coughing and lethargic, the baby who normally took a nap around midday fell asleep on her father at 9.30am.
Throughout the day the couple comforted their baby as she vomited at least four times from coughing. She couldn't eat but they managed to give her fluids.
"We put her to bed on Sunday night and she spewed all through her bed from coughing again. We called Healthline who said we had done all the right things."
With her temperature okay, the bed elevated, the humidifier on and her breathing fine, Healthline suggested keeping an eye on her.
"On Monday morning she was like a shell of herself. I booked her in at the doctor. They basically sent her to the hospital straight away," the mum said.
"She was in such a state."
The mother said her little girl was a tough cookie and had been discharged by Tuesday night.
"We had to have a feeding tube put in, which was horrible, and oxygen on and off during the night."
She said the children's ward was buys with children all struggling against the virus.
"So sad to see so many babies in there.
"There was a little one that was maybe six weeks and I shared a room with a lovely girl with a 4-month-old."
The mum understood how hard it was for parents to keep their child home from daycare, but said the other option was isolating at home for a week, following a stay in hospital.
"Try your best to keep your babies home when they have a barking cough."
Malaghan Institute of Medical Research director and immunologist Professor Graham Le Gros said the rise in cases across the country gave a clear-eyed insight into what a Covid-19 outbreak would look like.
"[It] is an important wake-up call of how vulnerable health systems are to serious infectious diseases that get into communities of susceptible people."
In contrast to other winter illnesses that affect the head and sinuses, Le Gros said RSV gets into the chest and lungs, causing pneumonia-like symptoms in children and the elderly.
"It's an illness that affects your lungs and reduces your breathing capacity and you could be coughing for five weeks afterwards," he said.
"It will get into an old person's home and go through everyone. People used to think it was influenza but it was probably RSV."
He said the severity of this year's outbreak was likely due to weakened immunity due to lockdowns, prior to an opening up of the transtasman bubble with Australia.
"We don't understand the full significance of why RSV is coming across as worse – is it a worse variant, or is it just because we missed a year due to extreme lockdown of boosting up our immunity by being exposed to the RSV going around?"
Senior lecturer at the University of Auckland nursing school Natalie Anderson said the outbreak was taking a toll on health staff.
"Caring for children and babies with breathing problems due to RSV is challenging, requiring both isolation precautions and close monitoring. Even where sick infants do not need hospitalisation, exhausted and anxious parents need guidance, reassurance, and support."
Lakes District Health Board paediatrician Dr Steve Bradley described RSV as a "really nasty and highly contagious" virus that affected but was not isolated to children.
"While it causes a fairly mild cold and maybe a mild chest infection in adults, young children and particularly babies can get really sick with it as it causes narrowing of the breathing tubes, which are already tiny in small babies."
Children could present with what starts as a cold and a runny nose but it would soon spread to the lungs, causing wheezing and difficulty breathing.