The two people who died from whooping cough this year were babies under one year old.
Doctors worry the country is on the brink of it's worst whooping cough epidemic in years because of low rates of childhood vaccination.
Te Whatu Ora announced the two deaths earlier this month but did not give the ages at the time.
The head of the Immunisation Taskforce and Māori paediatrician Owen Sinclair said the news was heartbreaking.
In the last whooping cough epidemic, in 2018, there were four deaths in total, he said.
"Just to have it happen so suddenly, such a tragic start to this current epidemic, is heart wrenching," he said.
The disease, also known as pertussis, was particularly dangerous for children, he said.
"Pertussis is a disease we hate. Once a child gets it there is nothing we can do about it. We just have to watch, almost helplessly, as a child can often cough themselves to be very sick."
Whooping cough epidemics tended to occur every four or five years. Cases had been low during the Covid-19 epidemic but were picking up, he said.
There had been eight cases notified in 2023, all but one of them children, and three children hospitalised.
Sinclair said there were likely to have been more cases, and the number was expected to rise over the next year to 18 months.
Since the last outbreak, in 2018, childhood immunisation rates have declined from 78 percent to 69 percent.
The rate was much worse for Māori children, down from 61 percent to 49 percent.
The fall was setting the stage for a worse epidemic than the one in 2013 where about 2000 children under one caught the disease over a two-year period, Sinclair said.
In communities with low immunisation rates, the disease would spread faster, meaning Māori communities were more at risk.
He urged everyone to check their baby was up to date with their vaccinations.
Whānau where a baby was due should also make sure adults and older children were vaccinated as they could pass it onto children, even if they have mild symptoms.
Sinclair told Morning Report the whooping cough immunisation was relatively easy for pregnant people to receive as it was carried out at a wide range of places, including pharmacies.
"You can just sort of rock up. And pharmacies are quite flexible, they are open long hours."
He said it was "slightly more difficult" for children.
To get the immunisation, Sinclair said children had to go to a general practitioner, which could be difficult as there were long wait times for appointments.
"We are trying to rebuild the system," he said.
Sinclair wanted better communication from health authorities about the danger of the disease and the importance of being immunised, saying any messages so far had lacked intensity.
RNZ
