The prevalence of human papillomavirus (HPV) infection in young women has declined by more than half since the introduction of the HPV vaccine, despite low vaccine uptake, claims a new study.
Researchers at the US Centers for Disease Control and Prevention (CDC; Atlanta, GA, USA) conducted a study that analyzed HPV prevalence data from the prevaccine (2003–2006), and the vaccine era (2007–2010), collected from US national health and nutrition examination surveys. HPV prevalence was determined by the linear array assay in cervicovaginal swab samples from females aged 14–59 years; 4,150 women provided samples in 2003–2006, and 4,253 provided samples in 2007–2010.
The results showed that among females aged 14–19 years, the vaccine-type HPV prevalence (HPV-6, -11, -16, or -18) decreased from 11.5% in 2003–2006 to 5.1% in 2007–2010, a decline of 56%. Among other age groups, the prevalence did not differ significantly between the two periods. The researchers stressed that the decline in HPV infection rate occurred despite the fact that only a third of eligible patients received the vaccine, and that vaccine effectiveness of at least one dose was 82%. The study was published in the June 19, 2013, issue of the Journal of Infectious Disease.
“Our data suggest an early impact of HPV vaccination on vaccine type prevalence among females in the United States and high vaccine effectiveness against vaccine type infection,” concluded lead author Lauri Markowitz, MD, and colleagues of the CDC. “The decline in vaccine type prevalence is higher than expected and could be due to herd immunity from vaccination, vaccine effectiveness of a series involving less than three doses, and/or changes in sexual behavior that we did not measure.”
“The results should challenge healthcare professionals to redouble their efforts to improve HPV vaccination rates, which lag far behind many undeveloped nations,” said Anne Schuchat, MD, director of the CDC's National Center for Immunization and Respiratory Diseases. “Here we're finding out about a vaccine that has greater than expected performance even with our pathetic coverage, and I think that this audience of highly motivated immunization experts and clinicians and program staff, I hope, see this as a wake-up call for us to do much better.”
Introduced in 2006, the first HPV vaccine covered the four viral strains most closely associated with gynecologic cancer (HPV-6, 11, 16, and 18). In June 2012, the CDC advisory committee on immunization practices (ACIP) recommended routine vaccination of 11- and 12-year-old girls with three doses of the quadrivalent vaccine, and catch-up vaccination of girls and young women 13 through 26. In 2009, the ACIP updated the recommendation to include the bivalent vaccine (HPV-16 and 18); two years later, ACIP recommended routine vaccination of boys and young men.
US Centers for Disease Control and Prevention