Canterbury health authorities are preparing to vaccinate about 1800 children in Ashburton, Methven and Rakaia to end a hepatitis A outbreak which began in April.
The Immunisation Advisory Centre said the mass vaccination campaign should rid the community of the outbreak; 28 cases have been confirmed in Ashburton, Methven and Rakaia since April.
The outbreak has been traced to one family who travelled overseas.
Immunisation Advisory Centre head Nikki Turner said the vaccine was safe and effective.
"If they can manage to vaccinate a large amount of the population where it is likely to be circulating, hopefully you should be able to stamp it out almost immediately," Dr Turner said.
The vaccine was not long-term protection against hepatitis A but would stop its spread in the short-term, she said.
Canterbury Medical Officer of Health Alistair Humphrey said Ashburton residents were doing all they could to get rid of the highly contagious virus.
Almost all cases have been linked to preschoolers, who often show no symptoms but still pass the virus to others, Dr Humphrey said.
"Parents and teachers are ensuring that everybody knows about washing their hands."
"Local businesses have vaccinated their food handling employees to ensure that it doesn't become a food-bourne outbreak from, for example, a parent of a toddler who spreads it via serving food," he said.
The vaccination campaign will cover all children aged one to five and will be funded by drug-buying agency Pharmac, which has listed the vaccine on its pharmaceutical schedule for a year.
Hepatitis A is a highly contagious virus which spreads rapidly when people do not wash their hands properly after going to the toilet.