A large international trial funded by GlaxoSmithKline Biologicals shows that the Cervarix vaccine is highly effective against infections with human papillomavirus (HPV) types 16 and 18. Final results of the Papilloma Trial Against Cancer In Young Adults (PATRICIA) were published July 8 in The Lancet.
Dr. Jorma Paavonen, of the University of Helsinki in Finland, and his colleagues in the PATRICIA study group followed 18,644 women aged 15 to 25 for a median of 34.9 months after vaccination (17,106 women received the full sequence of three injections). About half of the women were in a blinded control group that received a hepatitis A vaccine conferring no protection against HPV infection.
The Cervarix vaccine reduced the risk of precancerous lesions known as grade II cervical intraepithelial neoplasias (CIN2+) by nearly 93 percent in participants who completed the full sequence. The vaccine also provided a lesser but significant degree of cross-protection against HPV types 31, 33 and 45. This added protection could raise the potential effectiveness of HPV vaccination from about 70 percent to between 81 and 86 percent.
About 62 percent of women in the trial had never been exposed to any of the 14 HPV types associated with cervical cancer. This group is closest to the population targeted by universal mass HPV vaccination, said the authors, referring to young girls who are not sexually active. Only one event of CIN2+ was observed in 5,449 of these unexposed study participants.
Although it is important to continue testing for HPV in vaccinated and unvaccinated women, HPV vaccination has the potential to substantially reduce the incidence of cervical cancer and precancer, the authors concluded.
Cervarix is licensed in 90 countries and was approved last week by the World Health Organization, which allows United Nations agencies and partners to use the vaccine in developing countries. The vaccine is still under review and awaiting approval by the FDA.
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