STOCKHOLM, Sweden, March 16 (UPI) -- Beginning human papillomavirus vaccinations at a young age is important for maximizing its effectiveness, researchers in Sweden say.
Amy Leval of the Department of Medical Epidemiology and Biostatistics at Karolinska Institutet in Stockholm and colleagues looked at a group of females ages 10-44 living in Sweden between 2006-10, who were linked to multiple population registers to identify genital warts incidence in relation to HPV vaccination.
HPV vaccination programs have been launched around the world in hopes of preventing cervical cancer and other HPV-related cancers, the researchers said.
The study, published in the Journal of the National Cancer Institute, found females age 20 and older the rates of genital warts incidence decreased among the unvaccinated, suggesting women with a high risk of genital warts favorably used HPV vaccines.
The authors noted the study limitations: "Interpreting the crude estimates of effectiveness for those age 20 or older at first vaccination is difficult because we found evidence suggesting a self-selection bias with women at high risk preferentially seeking vaccination."