Health authorities say the vaccination of preschoolers in Ashburton is going well and on track to halt the spread of the Hepatitis A virus.
Ashburton is the centre of an outbreak of infectious Hepatitis A, with 28 confirmed cases since April.
Six mass vaccination clinics are being held this month, to vaccinate preschoolers to prevent further cases in adults and children.
Medical officer of health Alistair Humphrey says rain and cold meant a slow start to the clinics on Tuesday, but attendance has since picked up.
Dr Humphrey says they want to vaccinate about 12 hundred one to four year olds at the clinics, which end on 23 October.
"If we get 200 a day we'll achieve that, we'll more than achieve that with 200 a day, but we have really got to keep people coming in over this week and next week.
Dr Humphrey says it'll be late December or early January before they know if the programme has worked.
He says good handwashing remains important.