Up to 70% of sexually active women will become infected with HPV during their lifetime; it causes around 470,000 cases of cervical cancer each year, according to the article.

Although most cases of cervical cancer occur in the developing world, where organized cervical screening programmes have not been implemented, around 35,000 women die from the disease every year in Europe and the US.

HPV infections are also responsible for genital warts in 1-2% of young adults. Genital warts can cause sexual dysfunction. Recurrence is common and treatment is painful and expensive.

100% Protection Against Precancerous Lesions, Genital Warts

Luisa Villa of Ludwig Institute for Cancer Research, Brazil, and colleagues undertook a trial to test the effectiveness of a vaccine targeting the HPV types associated with 70% of cervical cancers (types 16 and 18) and 90% of genital warts (types 6 an 11). The investigators recruited 1,158 healthy women aged 16-23 to participate in the study from Brazil, Europe and the US.

The participants were not pregnant, had no previous abnormal cervical smears, and reported a history of four or fewer partners. 277 women were randomly assigned to the vaccine and 275 to a placebo. They received given intramuscular injections on day 1, month 2 and month 6.

Participants were followed up for 36 months and underwent regular gynecological examinations, sampling for HPV DNA and cervical smears. The incidence of persistent infection or disease with HPV 6, 11, 16, or 18 fell by 90% in those assigned the vaccine compared with those assigned the placebo.

The vaccine was 100% effective against precancerous cervical lesions and genital warts associated with these four HPV types. There were no vaccine related serious adverse events.

Vaccination of 10-13 Year-Olds Recommended

Universal HPV vaccination might be most effective if implemented in 10-13 year olds, who are likely to be HPV negative, the authors suggest. Large-scale trials of the vaccine are currently underway.

"In the developed world, full implementation of cervical-cancer screening has substantially shifted the burden of HPV infection from cervical cancer mortality to management of precancerous lesions," Dr. Villa comments.

"In these countries, in addition to further reduction in incidence of cervical cancer, universal HPV vaccination might decrease the medical, psychological, and economic costs associated with the management of abnormalities detected by screening," she adds.

"Inclusion of HPV 6 and 11 in a vaccine could also diminish the incidence of genital warts. In developing countries that have not implemented screening programmes for cervical cancer, a universal HPV vaccine could substantially reduce the incidence of the disease," concludes Dr. Villa.