Trends in genital warts diagnoses in New Zealand five years following the quadrivalent human papillomavirus vaccine introduction.

AIM

To investigate whether changes in rates of genital warts diagnosis at Auckland Sexual Health Service (ASHS), pre and post the quadrivalent human papillomavirus (4vHPV) vaccine introduction in late 2008, differed between clients vaccine-eligible and not eligible.

METHOD

All new clients attending ASHS from 2007 to 2013 were categorised as having genital warts or not. Generalised linear mixed models were used to compare differences in rates of change in diagnoses.

RESULTS

Overall, 43,480 were seen with genital warts diagnosed in 13.1%. The difference in rate of change over time in diagnosis pre- to post-vaccine differed in females vaccine-eligible to not (p=0.004). The relative risk of diagnosis per year pre-vaccine was 0.98 (0.84, 1.13) and post-vaccine 0.77 (0.74, 0.81) in those eligible compared to 0.87 (0.80, 0.95) and 0.95 (0.91, 0.98), respectively, in those not eligible. This difference in change, between vaccine eligible or not, differed between males and females (p=0.02), with males considered eligible if the same aged female would have been. In males, no difference in rate change pre- to post-vaccine could be shown in those eligible or not (p=0.53).

CONCLUSION

In this study a population effect for women of the 4vHPV vaccine was demonstrated.