"The most dangerous age for complications is children aged under one year. There have already been five cases in this age group so far this year, and two needed to be hospitalised," he said.
It was the violence of the coughing that did the most damage in babies. Young children often stopped breathing and turned blue after coughing, which was worse at night and could last for many weeks.
Adults could also catch whooping cough, and it is through adults that most young children were exposed, and contracted the illness.
Booster vaccinations were available for adults, and were recommended for those who worked or lived with infants. While vaccinations for children were free, there was no government subsidy for adults, who would need to pay.
"Whooping cough starts like the 'flu, but after a few days the bouts of coughing start," Dr Jarman said.
"The whoop is seen in about a half of children but only about one in 10 adults have the characteristic whooping sound at the end of the coughing bouts. Some people vomit at the end of the coughing; this is very suggestive of whooping cough."
The key to best protection was vaccinations being administered "on time". Some parents opted to postpone their children's immunisation appointments due to a runny nose or a cold but Dr Jarman urged parents to consult their GP rather than doing that.
"If you are unsure, talk to your family doctor or nurse. They can advise whether it is still safe to immunise, or make an alternate arrangement," he said.
"Immunisation is free, safe, and when a child is vaccinated on time every time, very effective."
More information about immunisation, the National Immunisation Schedule is available at www.moh.govt.nz/immunisation, while the Immunisation Advisory Centre offers independent advice about immunisation through its toll-free line 0800 IMMUNE (0800 466-863) and its website (www.immune.org.nz).
