Marshall said they have the ability to utilise other clinical areas and call in additional staff if needed.
He said adults and older children get milder RSV illness but can pass it on to babies, so they are urging people to take precautions.
"Maintain good hand hygiene, stay home if they have any symptoms of a respiratory tract illness, keep children home from daycare or kindergarten if they have coughs and colds, and wear masks on public transport."
New Zealand Royal College of GPs medical director Dr Bryan Betty said he had seen an upswing in respiratory illnesses in children in his own Porirua practice.
"We saw none of it last year mainly due to the lockdown of the borders," he said.
"This year it's re-emerged and it's caused quite a bit of pressure on both general practice and hospitals."
A common winter condition, RSV causes inflammation of the lungs and respiratory tract. Betty said it could be severe in children without immunity, causing some to be admitted to ICU in very rare cases.
"There's certainly been a lot of admissions and presentations to emergency departments, urgent aftercare facilities and being admitted onto wards in hospitals."
"Potentially some children can end up in ICU, it's something that can happen in rare instances."
Capital & Coast and Hutt Valley DHBs advised people to contact Healthline on 0800 358 5453 or their GP for advice.