A vaccination researcher says 'no jab no play' policies could see kids punished for the actions of their parents.

The vaccination policies are coming into force nationwide to prevent children who are not fully vaccinated from attending preschool unless they have a valid medical reason.

At a national immunisation conference this week, Sydney University associate professor Julie Leask said the scheme did not do much for parents who do not vaccinate.

“Some vaccine objectors have changed their minds and decided to vaccinate, others have dug in,” she said.

“We're hearing in our research … that there were parents who were sort of on the fence before and because they're feeling coerced, have definitely dug in and they're not going anywhere near vaccination.”

Associate Professor Leask said children risk missing out on early childhood education because of their parents’ concerns.

“We want high vaccination uptake, we want it in a way that's ethically sustainable and doesn't punish children for the decisions of their parents,” she said.