Elizabeth Crowe, MB, ChB, from University of Queensland in Brisbane, Australia, and colleagues evaluated the effectiveness of the quadrivalent HPV vaccine against cervical abnormalities four years after implementation of a nationally funded vaccination program in Australia. The evaluation included women eligible for free vaccination (aged 12–26 years in 2007) and having their first cervical smear test between April 2007 and March 2011. There were 1,062 high-grade cases (histologically confirmed cervical abnormalities); 10,887 “other cases” (with any other cytology or histology abnormality); and 96,404 controls with normal cytology.
The researchers found that the adjusted odds ratio for those receiving three doses of HPV vaccine versus no vaccine was 0.54 for high-grade cases and 0.66 for other cases, compared to controls. This yields a vaccine effectiveness of 46 and 34%, respectively. The adjusted numbers needed to vaccinate were 125 and 22, respectively. For two vaccine doses, the adjusted exposure odds ratios were 0.79 for high-grade cases and 0.79 for other cases, yielding a vaccine effectiveness of 21%.
“The quadrivalent HPV vaccine conferred statistically significant protection against cervical abnormalities in young women who had not started screening before the implementation of the vaccination program in Queensland, Australia,” the authors write.
Several authors disclosed financial ties to pharmaceutical companies, including manufacturers of HPV vaccines.