Dr Morreau said epidemics occurred around every three to five years. If not enough people are immunised there is no herd immunity to stop diseases going through the community and the disease resurges.
"The reality is if we don't ensure herd immunity by ensuring everyone is fully immunised on time, babies will continue to die from diseases like whooping cough. All of this is preventable if people are immunised properly."
As a young doctor working in the United Kingdom in the late 1970s when whooping cough immunisation rates were at a significant low, he saw two very young babies come to hospital having died during their coughing bouts.
"The babies coughed themselves to death and we couldn't save them. Fortunately death is uncommon, but while more often just a mild illness in older children and adults it can be very serious, particularly for the very young. There can be significant complications as well as a distressing 100 day cough which is awful for babies and their families. It's a horrible disease. If anyone is in any doubt they should look at the videos on the Ministry of Health site showing a baby that's got whooping cough and the horrible coughing they experience."
Whooping cough is a highly infectious and distressing illness caused by bacteria that are spread through the community by coughing and sneezing, in the same way as colds and influenza. Symptoms start with a runny nose, fever and dry cough. Coughing gets worse over the next few weeks developing into attacks of coughing and sometimes vomiting. The 'whoop' sound occurs as a baby draws a breath after a long coughing attack.
The most effective way to protect babies is for their mother to be immunised during pregnancy (between 28 and 38 weeks) so that antibodies are passed on to the baby. These antibodies will help reduce the likelihood of the baby becoming ill with whooping cough before their first immunisation at six weeks.
Dr Morreau said it was important that babies got that first immunisation on time and further childhood immunisations are required at 3 months, 5 months, 4 years and 11 years to ensure ongoing protection.
If you are worried about your baby, for free advice phone Healthline on 0800 611 116, or see your GP.
If you're not sure if you or your family members are up to date with immunisations, please contact your family doctor to check.
For more information visit http://www.health.govt.nz/your-health/conditions-and-treatments/diseases-and-illnesses/whooping-cough.