From this week, children who are not fully vaccinated can now be excluded from enrolling in childcare and kindergartens in Western Australia.

Earlier this year, State Parliament passed the "no jab, no play" legislation, amending the Public Health Act and allowing the chief health officer to prevent those children who are not immunised from going to early education centres.

"We know that vaccinations save lives," Communities Minister Simone McGurk said at the time.

"That's why it's important that we send the message to all West Australian families that they need to get their children up-to-date with all the vaccinations that are freely available in our state, free of cost."

Children who are already enrolled in 2019, but not fully vaccinated, can continue to be enrolled for the rest of the year.

The Health Minister believes 98 per cent of WA parents believe in the immunisation schedule. ( Flickr: Juliana Thomas/International AIDS Vaccine Initiative )

New South Wales, Victoria and Queensland already have similar laws in place and Ms McGurk said those states had seen an increase in levels of vaccination.

The Commonwealth Government has a "no jab, no pay" policy, linking some family benefits to the immunisation schedule.

Why is it happening?

Health Department figures show last year the state's immunisation coverage was lower than the national average for children aged one, two and five.

One- and five-year-old children in Western Australia had the lowest immunisation rates in the country compared to other jurisdictions, at 93.5 per cent and 93.4 per cent respectively. Two-year-old children had the second lowest at 90.2 per cent.

The ban will only apply to children in pre-primary and below. ( StockSnap.io: Freestocks.org )

"This is the State Government's response to very low vaccination rates in Western Australia, amongst the lowest in the country," Ms McGurk said

"In some categories, age categories, we have the lowest vaccination rates in the country."

She said parents might expect their children could pick up a cold or a stomach bug at childcare, but not an entirely preventable and possibly fatal disease which could be vaccinated against.

Ms McGurk said she wanted to send the message that children should be vaccinated and the community would be better off if these diseases were prevented.

How many children could be affected?

A department audit found 3,703 children in childcare or kindergarten were either not up to date with their immunisations or their status was unknown, and they were presumed to not be vaccinated.

Ms McGurk said many of these were not intentional.

Simone McGurk believes some families just are not aware of the vaccination schedules. ( ABC News: Rebecca Carmody )

"Many of those families are just not aware of the vaccination schedules, or they are busy and have not kept up to date," she said.

The Health Department estimates 98 per cent of WA parents believe in the immunisation schedule.

Ms McGurk said a very small number of people did not believe in the science and were "conscientious objectors". She said immunisation was not compulsory, but it was if they wanted to access childcare.

"We are saying to those families we want our public policy to be guided by science, and that is why we encourage all families in WA to use our vaccination scheme," she said.

What is the benefit of no jab, no play?

The aim is to achieve what is known as herd immunity, where at least 95 per cent of children are vaccinated from potentially deadly diseases.

That protects people who are too young to be vaccinated, pregnant women, children with certain immune disorders and some cancer patients.

The Health Department said the diseases could be extremely serious for these people.

Ms McGurk says immunisation is not compulsory, but it is if parents want to access childcare. ( ABC News: Natasha Johnson )

"It means they are safe because enough children have the vaccinations," Ms McGurk said.

"This is another opportunity to say to those families we have a good quality system … we want you to avail yourself of these good quality care services, but we also want children to be safe in these services."

Are there any exemptions?

Yes. Children with natural immunity to certain diseases, or who have health vulnerabilities, are medically excluded from the law.

Children on an approved schedule to have their vaccinations done will also be allowed to enrol.

But Ms McGurk said the vast majority of children would be required to be immunised.

She said the aim was not to exclude families from childcare, rather the opposite, and to remind parents to keep their vaccinations up to date.