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 its 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 says the news is heartbreaking.

In the last whooping cough epidemic, in 2018, there were four deaths in total, he says.

"Just to have it happen so suddenly, such a tragic start to this current epidemic, is heart wrenching."

The disease, also known as pertussis, is particularly dangerous for children, he says.

"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 tend to occur every four or five years. Cases have been low during the Covid-19 epidemic but are picking up, he says.

There has been eight cases notified in 2023, all but one of them children, and three children hospitalised.

Sinclair says there are likely to have been more cases, and the number is 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 is much worse for Māori children, down from 61 percent to 49 percent.

The fall is 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, says Sinclair.

In communities with low immunisation rates, the disease would spread faster, meaning Māori communities were more at risk.

He urges everyone to check their baby is up to date with their vaccinations.

Whānau where a baby is due should also make sure adults and older children are vaccinated as they could pass it onto children, even if they have mild symptoms.

Sinclair wants 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.

-Rowan Quinn/RNZ.