Girls aged between 14 and 17 years experienced early beneficial effects with the quadrivalent HPV vaccine; therefore, offering additional justification for not delaying vaccination, according to new study findings.
Researchers observed decreases in cervical dysplasia and possible decreases in the occurrence of anogenital warts.
While previous research have shown the quadrivalent HPV vaccine (Gardasil, Merck) to be highly effective against vaccine-type–specific cervical dysplasia and anogenital warts, few studies have examined the vaccine’s effects in the real world setting and none have done so at the program/population level, according to Leah M. Smith, MSc, of the department of public health sciences at Queen’s University in Kingston, Ontario, and colleagues.
For this reason, the researchers sought to assess the impact of the quadrivalent HPV vaccine and Ontario’s eighth grade quadrivalent HPV vaccination program on the rates of cervical dysplasia and anogenital warts. The time before program implementation (2005/2006-2006/2007) was compared with the time after program implementation (2007/2008-2008/2009). Data were pooled on exposure to the vaccine for grades 8 and 9 and outcomes were assessed in grades 10 and 12.
According to study results, there were 2,436 cases of dysplasia and 400 cases of anogenital warts. The incidence for dysplasia was significantly decreased with vaccination by 5.7 per 1,000 girls (95% CI, – 9.91 to – 1.5); this corresponded to a relative reduction of 44% (RR = 0.56; 95% CI, 0.36-0.87).
Overall, there were 131,781 girls who were ineligible for the program and 128,712 girls eligible for the program. The researchers found that program eligibility had a significant protective effect on dysplasia with a risk difference of – 2.32 per 1,000 (95% CI, – 4.02 to – 0.61; RR = 0.79; 95% CI, 0.66-0.94).
Moreover, decreases were observed in anogenital warts due to vaccination (risk difference of – 0.83 per 1,000; 95% CI, – 2.54 to 0.88; RR = 0.57; 95% CI, 0.2-1.58) and program eligibility (risk difference of -0.34 per 1,000; 95% CI, – 1.03 to 0.36; RR = 0.81; 95% CI, 0.52-1.25).
“The fact that these benefits were observed in such a young age group strengthens current recommendations that vaccination should occur at an early age,” the researchers wrote. “As such, policy makers and physicians can use these findings to substantiate arguments that delaying vaccination may result in missed opportunities for prevention.”
Disclosures: The researchers report no relevant financial disclosures.