Waikato medical officer of health Anita Bell is urging families expecting babies or with newborns to get them vaccinated for whooping cough.
Waikato has had an epidemic of whooping cough or pertussis for about a year and a half.
Two hundred and five cases have been notified so far this year, up from 63 at the same time last year.
Free vaccinations were introduced for pregnant women in November by Waikato District Health Board, which is now extending the offer to partners and others in the household.
Ms Bell said whooping cough is particularly dangerous for babies. They can't be given vaccinations until they are six weeks old.