NY Times By Nicholas Bakalar
The prevalence of cancer-causing HPV strains has dropped markedly in women who have been vaccinated.
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.
The prevalence of genital warts also decreased sharply in women and, thanks to herd immunity, in unvaccinated men. Cases of precancerous cervical lesions decreased by 51 percent among girls 15 to 19, and by 31 percent among women 20 to 24.
“HPV infections, the cause of cervical cancer and precancerous lesions, are significantly declining in countries with high vaccination coverage,” said the senior author, Marc Brisson, a professor of epidemiology at Laval University in Quebec City.