Schoolgirls who have the free cervical cancer vaccine almost halve their risk of getting serious abnormalities in the cervix, Australian research shows.
The study, published in the British Medical Journal, is one of the first to show the impact of the human papilloma virus in the "real world" rather than estimates.
Queensland researchers found Australia's HPV vaccination program reduced the risk of cancer-causing high-grade abnormalities by 46 per cent in young women who were fully vaccinated before their first Pap smear test.
Scientists at the University of Queensland and QIMR Berghofer Medical Research Institute said the results showed the value of the school vaccination program which started in 2007.
Study spokesman David Whiteman said Australia was one of the first countries to undertake mass HPV vaccination.
"We always knew the vaccine was safe and effective in the narrow, controlled environment of clinical trials, but this significant study proves its 'real world' value on a broad scale," Professor Whiteman said.
"By preventing those cervical changes that are a precursor to cancer, the vaccination program saves lives and minimises future health expenditure."
The vaccine, developed by Professor Ian Frazer, is given as three doses over six months and is free for girls and boys in the first year of high school.