Prevalence of HPV genotypes targeted by a quadrivalent vaccine fell by more than half among young women in the 8 years following introduction of the vaccine, study data showed.
“By 2014, almost all vaccine being used in the United States was quadrivalent vaccine, which targets HPV types 6, 11, 16 and 18; during this time, vaccination was recommended in a three-dose schedule. Since HPV vaccine introduction in 2006, coverage has increased but has remained lower than other immunizations recommended for adolescents,” Sara E. Oliver, MD, MSPH, of the National Center for Immunization and Respiratory Diseases at the CDC, and colleagues wrote. “One of the early measures of vaccine impact is a decline in vaccine-type infection.”
Sara E. Oliver
The researchers evaluated self-collected cervicovaginal specimens, as well as self-reported vaccination data, from female participants aged 14 to 34 years old. All data were collected as part of the National Health and Nutrition Examination Survey. The researchers estimated HPV prevalence from 2003 to 2006 – the period immediately before the introduction of the vaccine—and compared it with prevalence from 2007 to 2010, and 2011 to 2014.
In the group aged 14 to 19 years, HPV prevalence fell from 11.5% in the 2003 to 2006 period (95% CI, 9.1%-14.4%) to 3.3% (95% CI, 1.9%-5.8%) in the 2011 to 2014 period, during which time coverage with at least one dose was 55%, the researchers reported. Among women aged 20 to 24 years, prevalence fell from 18.5% (95% CI, 14.9%-22.8%) in the 2003 to 2006 period to 7.2% (95% CI, 4.7%-11.1%) in the 2011 to 2014 period, when the coverage rate was 43%.
The prevalence of quadrivalent-type HPV fell 89% overall among vaccinated women, and 34% among unvaccinated women, Oliver and colleagues wrote. The group aged 14 to 19 years showed a 71% decrease, whereas those aged 20 to 24 years aged 61%. The researchers reported a vaccine effectiveness of 83%.
“Over time, we expect to observe decreases in prevalence among older age groups, as persons vaccinated at the recommended ages reach their late 20s and 30s,” the researchers wrote. “In 2016, a two-dose HPV vaccination schedule was recommended for persons initiating vaccination at ages 9 to 14 years. Continued efforts are needed to increase HPV vaccination coverage in the United States, and further impact can be anticipated with increased coverage among the targeted population.” – by Andy Polhamus
Disclosure: The researchers report no relevant financial disclosures.