The vaccine against HPV, introduced in 2006, appears to be very successful in preventing cancer in real-world circumstances.

HPV, or human papilloma virus, is a common sexually transmitted disease, and while most cases are harmless, some types of the virus can cause genital warts and cancer.

Researchers reviewed 40 studies of HPV infection in 14 high-income countries, with data from more than 60 million people followed for up to eight years after vaccination. The study is in The Lancet.

They found that the prevalence of HPV 16 and 18, which cause most cases of cervical cancer, decreased over the period by 83 percent among girls ages 13 to 19, and by 66 percent among women 20 to 24. Infection with three other high-risk types, 31, 33 and 45, decreased 54 percent among girls 13 to 19.