Fifty cases of whooping cough were reported to the Canterbury District Health Board between November 2016 and March 2017, with the majority of people who had the virus being under the age of 15.
Canterbury's Chief Medical Officer of Health, Dr Ramon Pink, said new-born children had the biggest risk of picking up harmful viruses such as whooping cough.
He said new-born children had extreme consequences to their health if they were not immunised.
Pink said the first vaccination at 6 weeks-old was a platform for ensuring that a child avoided serious illnesses from family members and friends.
Expecting mothers who are 28-38 weeks into their pregnancy have been strongly encouraged by General Practitioner's and the Canterbury District Health Board to get a vaccination prior to giving birth.
Pink said it was a great way to protect mothers and give unborn children anti-bodies to fight viruses as soon as they were born.
"The vaccination is actually safe during their pregnancies for these illnesses, so we have to keep promoting the safety of the vaccine and the benefits," Pink said.
As a district, Canterbury stood above the national average of child immunisation at 95%, but Pink said it was still too low.
He said promotion of the safety of vaccinations for pregnant mothers needed to continue, and hoped to create a 'change of mentality' in Canterbury communities.