Health officials are urging any Ashburton families with preschoolers not yet vaccinated against hepatitis A to get it done.
Wednesday is the last in a series of four mass vaccination clinics in the mid-Canterbury town, which is battling the highly infectious virus.
Ashburton is the centre of an outbreak of infectious Hepatitis A, with 28 confirmed cases since April. The outbreak was traced to a family who travelled overseas.
Medical Officer of Health Alistair Humphrey said the campaign was going well but he would like more children to be vaccinated, to be on the safe side.
One clinic will be held in Methven and one in Rakaia on Wednesday next week.
In total, health authorities hope to vaccinate about 1500 children aged one to five to halt the spread of the virus.