A new government study investigating the prevalence of human papillomavirus (HPV) infections in females aged 14 to 59 before and after the introduction in 2006 of the HPV vaccine found that the rate of the HPV infection dropped by 56%, decreasing from 11.5% in 2006 to 5.1% in 2010 among female teenagers aged 14 to 19. Despite the success of the vaccine, only 32% of teenage girls aged 13 to 17 received the recommended three doses in 2010 and 49% received only one dose.
The study, conducted by the Centers for Disease Control and Prevention and published recently in The Journal of Infectious Diseases,1 analyzed data from the National Health and Nutrition Examination Survey (NHANES) to compare prevalence of certain types of HPV in females before the start of the HPV vaccination program (2003-2006) with the rate of infection after the vaccine was introduced (2007-2010). Study researchers used the Linear Array HPV Assay in cervicovaginal swab samples taken from girls and women aged 14 to 59 to determine infection prevalence.
About 79 million Americans, most in their late teens and early 20s, are infected with HPV, and each year about 14 million become infected. According to CDC figures, each year about 19,000 cancers caused by HPV occur in women, with cervical cancer the most common, and about 8,000 cancers caused by HPV occur each year in men, with throat cancer the most common.
Wake-up Call to the Nation
CDC Director Tom Frieden, MD, MPH, issued a statement saying: “This report shows that HPV vaccine works well, and the report should be a wake-up call to our nation to protect the next generation by increasing HPV vaccination rates. Unfortunately, only one-third of girls aged 13 to 17 have been fully vaccinated with HPV vaccine. Countries such as Rwanda have vaccinated more than 80% of their teen girls. Our low vaccination rates represent 50,000 preventable tragedies—50,000 girls alive today will develop cervical cancer over their lifetime that would [be] prevented if we reach 80% vaccination rates. For every year we delay doing so, another 4,400 girls will develop cervical cancer in their lifetimes.”
In addition to the unexpected effectiveness of the partial dosage of the HPV vaccine, another possible explanation for the sharp decline in HPV prevalence may be herd immunity, in which people who are vaccinated reduce the overall prevalence of the virus in the general population, thereby decreasing the chances that unvaccinated people would be exposed to someone who is infected, according to study lead author Lauri E. Markowitz, MD, the team leader in Epidemiology Research in the Division of Sexually Transmitted Disease Prevention at the CDC.
Growing Parental Resistance
Although a provision in the Affordable Care Act calls for insurance providers to cover the full cost of the HPV vaccine, eliminating one of the potential reasons for low vaccination rates, parental opposition to the vaccine is growing. According to a study published in Pediatrics,2 in 2010, 44% of parents said they had no intention of vaccinating their daughters, up from 40% in 2008, because their daughters were “not sexually active” and they had concerns about the vaccine’s safety.
HPV Vaccine Recommendations
The CDC recommends that routine HPV vaccinations of three shots over 6 months begin at age 11 to 12 for both boys and girls. The vaccine is also recommended for older teens and young adults who were not vaccinated when they were younger. ■
References
1. Markowitz LE, Hariri S, Lin S, et al: Reduction in human papillomavirus (HPV) prevalence among young women following HPV vaccine introduction in the United States, National Health and Nutrition Examination Surveys, 2003–2010. J Infect Dis. June 19, 2013 (early release online).
2. Darden P, Thompson DM, Roberts JR, et al: Reasons for Not Vaccinating Adolescents: National Immunization Survey of Teens, 2008–2010. Pediatrics. March 18, 2013. (early release online).
