The early impact of human papillomavirus vaccination on anogenital warts in Québec, Canada

Abstract

In Québec province in Canada, a public school-based and catch-up HPV vaccination programs with the quadrivalent vaccine have been introduced in September 2008 for girls aged 9-17 years. We assessed the early impact of the HPV vaccination program on the incidence of anogenital warts (AGW) in the Quebec general population. We used the provincial health administrative data of the Régie de l'assurance maladie du Québec (RAMQ). AGW were identified either through a prescription of podofilox, or a medical procedure code specific to AGW, or a diagnostic code for viral warts followed by a prescription of imiquimod or fluorouracil. Sex- and age-specific incidence rates were calculated for pre-vaccination (2004-2007) and vaccination (2009-2012) periods. We found a significant decline of 45% and 19% in the incidence of AGWs among females aged 15-19 and 20-24 years, respectively. A decline of 21% was also seen among males aged 15-19 years. The median age at an episode of AGW increased from 27 years in 2004 to 31 years in 2012 among females and remained stable in males. Our findings indicate that the HPV public vaccination program is associated with an important reduction in the incidence of AGW among young females and males. The benefit is more pronounced among females 15-19 years of age, who were eligible for the public vaccination program. The observed decline among young males could be due to herd immunity and/or privately paid vaccination.

A Review of the Impact and Effectiveness of the Quadrivalent Human Papillomavirus Vaccine: 10 Years of Clinical Experience in Canada

“…Moreover, a small but significant decline of 21% (P = 0.004) was also seen in boys and young men aged 15 to 19, but not in older men. Interestingly, in women, the median age at an episode of AGW increased from 27 3C). However, these results were not statistically significant.…”

Human Papillomavirus Vaccination and Anogenital Warts: A Systematic Review of Impact and Effectiveness in the United States

“…For example, a study in Ontario, Canada did not observe decreases in males of any age after beginning female vaccination while another study set in Quebec during the same time period found decreases of 21% in males aged 15 to 19 years. 24,25 These findings suggest that in countries with moderate vaccine uptake like the US, herd immunity may only play a low to modest role in preventing disease. Estimates of vaccine effectiveness in the US were also comparable to that observed in other counties; a provincial cohort study in Canada found a 56% vaccine effectiveness against anogenital warts among those who received three doses before the age of 18.…”

Reduction in the utilization of prednisone or methotrexate in Canadian claims data following initiation of etanercept in pediatric patients with juvenile idiopathic arthritis

“…Per privacy legislation in Quebec, a random sample drawn from the total RAMQ database was used in this study. These databases have been utilized previously in many studies evaluating the use of biologics and other medications in adult and pediatric patient populations [7, 8, 25–29].…”