Teenagers in Macedon Ranges and Hume are being urged to get immunised against cancer-causing HPV as the new school year begins.

Data released by the Australian Institute of Health and Welfare revealed that not all eligible teenagers are taking advantage of the free immunisation program provided in schools.

The data showed 20 per cent of girls living in the north west of Melbourne, taking in Hume and the Macedon Ranges, were not fully immunised against HPV in 2015-16.

About 24 per cent of boys living in the same region were also not fully immunised during the same period.

The HPV vaccine, known as Gardasil 9, is provided to all year 7 students for free under the National HPV Vaccination Program.

The vaccine protects against nine types of HPV which causes about 90 per cent of cervical cancers in women and 95 per cent of all HPV-related cancers in men.

Cancer Council Victoria’s screening, early detecting and immunisation manager, Kate Broun said while vaccination rates were in line with the state average, it was still crucial that all eligible teenagers participate in the vaccination program.

“It is fantastic that lots of … parents are choosing to protect their children, but there is still work to be done to ensure that all teens have the opportunity to complete the free vaccine course and protect themselves against cancer-causing HPV,” she said.

“The vaccine is most effective when given at age 12-13. Two injections are needed with the second dose administrated six to 12 months after the first. We are urging parents to sign the vaccine consent form and ensure their teen receives both doses.”

According to Cancer Council Victoria, there has been a 93 per cent reduction in the two most serious types of HPV since the vaccination program was implemented in 2007.