Cases of the infectious RSV illness are now spreading in the South Island, with Dunedin and Invercargill hospitals starting to see cases.
Cases of RSV, or respiratory syncytial virus, have broken out among children in New Zealand this winter and are overwhelming hospitals.
District health boards continue to restrict visitors in an attempt to curb the virus' spread, but a paediatrician has warned the worst is yet to come.
Southern DHB paediatrician Professor Barry Taylor is bracing the team for what's to come as more babies get sick across the country.
"I would expect us to be seeing the full onslaught of RSV probably over the next week," he says.
Older children and adults are starting to test positive too.
In Invercargill, the children's ward at Southland Hospital has been at capacity all week, and nine out of 10 kids in isolation are battling a respiratory illness.
"For some reason, it's arrived in Southland slightly before Dunedin but it does mean we have got even more time for planning," Taylor says.
The Southern DHB is calling on the public to exercise extreme care visiting high-risk wards across the lower South Island.
On Thursday, Whangārei, Wellington, and Hutt Valley hospitals all placed restrictions on children visiting wards there.
Health Minister Andrew Little says DHBs have enough PPE as patient numbers soar.
"All hospitals are always prepared for winter spikes in infections, we're seeing a winter spike in infection and they're being supported to meet the demand that's on them," he says.
There's currently no vaccine for RSV, but the option is on the horizon. Trials are underway at the moment, including here in New Zealand.
"In 20 years of paediatrics, bronchiolitis with RSV is your bread and butter and it would be lovely to see that change," paediatrician Dr Rebecca Griffith says.
Mum-to-be Heidi Wilde is part of the study where pregnant women are given the vaccine in the hope it'll pass on immunity to the baby.
"As a new mum I would do anything I can to make sure my little boy's protected," she says.
But for other families, keeping sick children at home is the best protection we've got.
