Pregnant women and mothers of newborn infants in Canterbury will get free immunisation against pertussis (whooping cough).
Women who are more than 30 weeks pregnant and mothers up to two weeks after childbirth are eligible for the treatment.
Canterbury Medical Officer of Health Dr Ramon Pink says the offer is a response to the region's pertussis epidemic.
There have been 515 confirmed or probable cases in the region since August 2011. Twenty-seven babies under one have had pertussis and 15 of those have been hospitalised. Two were sent to Starship Hospital in Auckland for treatment.
Children receive free immunisation against pertussis as part of the national immunisation schedule. Ensuring children get their vaccinations at six weeks, three and five months and four and 11 years old is crucial to controlling the current epidemic, doctors say.