Parents are being reminded of Victoria's no jab, no play laws as they prepare for the new school year.
All youngsters attending child care and kindergartens must have current vaccination certification.
Since their introduction in 2016, the laws have seen Victoria surpass the herd immunity target of 95 per cent.
Immunisation rates for children under five years remain steady at 95.4 per cent, according to the state government.
"If you're not immunising your child, you're doing a grave disservice to your child," acting premier Tim Pallas told reporters on Thursday.
Only Immunisation History Statements from the Australian Immunisation Register will be accepted as evidence of a medical reason why a child is not immunised when enrolling in child care or kindergarten.
Western Australia has also implemented no jab, no play laws starting from this year.
Since January 1, all kindergartens, schools and child care centres will be required to keep up-to-date immunisation records, and the Health Department's chief health officer will have power to order under-vaccinated children to stay home.
The laws also exist in NSW and Queensland.
Across Australia, children must be fully immunised in order for their parents to receive federal government payments.
Federal Health Minister Greg Hunt said on January 3 that up to 250,000 children have taken up new vaccinations since the initial no jab, no pay policy started three years ago.
Australian Associated Press