Children in Italy have been told not to bother coming to class unless they can prove they've been vaccinated.
The ruling comes after the European nation concluded months of national debate over the issue of compulsory vaccination.
The country introduced the new laws following a spike in measles cases. Parents now risk being fined €500 ($825) if they send their children to school, and children under 6 can be sent home.
The new measures are called the Lorenzin laws, named after the former health minister Beatrice Lorenzin who called for their introduction.
Now in effect, parents who want their kids in school must have them jabbed with a range of standard vaccines including chickenpox, polio, measles, mumps and rubella.
Children whose parents cannot prove they have been vaccinated up to the age of 6 will be excluded from preschool and kindergarten. Kids and teens between the ages of 6 and 16 can't be banned from school, but their parents can be whacked with fines if their kids aren't immunised.
The original deadline for the introduction of the Lorenzin law was March 10, but it was extended to Monday as it fell on a weekend.
"Now everyone has had time to catch up," Giulia Grillo, Italian Health Minister, told La Repubblica.
"No vaccine, no school."
She has reportedly resisted pressure from the Deputy Prime Minister to extend the deadline.
In Bologna, local authorities sent suspension letters to the parents of 300 different students. In that area a suspected 5000 don't have appropriate vaccination documents.
In other areas schools are extending their own deadlines and giving grace periods, according to the BBC.
VACCINATION RATES IN ITALY
Italy currently has a low vaccination rate of 80 per cent. The World Health Organisation has a target of 95 per cent, at which point they say "herd immunity" starts to take effect and protects parts of the community who cannot be vaccinated.
This includes babies who are too young to be vaccinated, or those with a medical condition that compromises their immune system.
The Lorenzin law was drafted by Italy's previous government. When the current government came to power they suggested they would drop the policy but the recent measles outbreak retriggered debate about immunisation.
Health Minister Grillo admitted her party had previously "criticised" the law for "several reasons". She said the law was based on scientific data.
Two Italian populist political parties have faced accusations that they were pursuing anti-vax policies.
THE ANTI-VAX MOVEMENT
The anti-vax movement, founded by discredited British doctor Andrew Wakefield, has enjoyed a resurgence in recent years.
Wakefield, a former gastrointestinal surgeon originally released a study in 1992 claiming the measles, mumps and rubella vaccine was linked with autism and bowel disease.
The claims were explosive, and in the decade following Wakefield's publishing his findings, vaccination rates in the UK dropped from over 90 per cent to below 79 per cent by the start of 2003.
However, in 2004 a journalist revealed the families of the children in the study, who were in the midst of trying to sue the vaccine company, had got their solicitors to hire Wakefield to carry out the study.
Wakefield had his medical licence revoked and he turned to making documentaries about vaccines.
After being rejected by the medical community and the media, Wakefield moved to the United States, where he produces documentaries and writes books.
Wakefield credits Facebook groups and social media with his career renaissance, saying these platforms make up for the "failings of the mainstream media".
"No one knows quite what to believe. So people are turning increasingly to social media," Wakefield told The Guardian in 2018.