Gardasil significantly reduces prevalence of HPV strains among females
Implementation of Gardasil quadrivalent HPV vaccine in 2006 significantly reduced the prevalence of HPV-6, -11, -16 and -18 strains among girls and young women aged 14 to 24, according to recent research in Pediatrics.
“Our data confirm previous findings of an early impact of HPV vaccination in the United States among females aged 14 to 19 years and extend the findings to females in their early 20s,” Lauri E. Markowitz, MD, of the CDC’s National Center for HIV/AIDS, Viral Hepatitis, STD and TB Prevention, and colleagues wrote. “The decline in vaccine type prevalence after introduction of HPV vaccination is greater than expected based on current 3-dose coverage.”
The researchers used nationally representative NHANES survey data, which collected samples and demographic data from girls and women aged 14 to 34 years. To determine the effect of vaccination on the prevalence of specific HPV strains, data from the pre-vaccine era (2003 to 2006) was compared with data from the post-vaccination era (2009 to 2012), for girls aged 14 to 24 years. The researchers examined the prevalence of the four specific strains of HPV covered by Gardasil (4vHPV, Merck).
Study results showed that prevalence of 4vHPV strains decreased 64% among adolescent girls aged 14 to 19, and 34% among women aged 20 to 24 years, within 6 years of vaccine introduction. Prevalence declined from 11.5% to 4.3% among the younger group and from 18.5% to 12.1% among the older group. Study findings also showed that 4vHPV strains were more prevalent among unvaccinated sexually active girls compared with sexually active girls who received at least one dose of 4vHPV (16.9% vs. 2.1%).
The researchers said there was no statistically significant reduction in the prevalence of HPV types not protected by 4vHPV.
“Given the low contribution of vaccine types to the overall prevalence of HPV in the population and because coinfections occur, a decrease in any HPV prevalence due to the declines in vaccine type HPV might not be observed, particularly if there is any increase in sexual risk behavior in the population,” Markowitz and colleagues wrote. – by David Costill
Disclosure: The researchers report no relevant financial disclosures.