Measuring human papillomavirus (HPV) vaccination coverage and the role of the National HPV Vaccination Program Register, Australia Dorota M. Gertig A , Julia M. L. Brotherton A,B and Marion Saville A A Victorian Cytology Service, PO Box 161, Carlton South, Vic. 3053, Australia. B Corresponding author. Email: jbrother@vcs.org.au Abstract. Accurate estimates of HPV vaccination coverage are critical for determining the proportion of the target female population that is not protected by the vaccine, as well as for monitoring the performance of vaccine delivery programs. The implementation of an HPV vaccination register, either as part of an existing immunisation register or stand- alone, can add substantial benefits to an HPV vaccination program. In Australia, the National HPV Vaccination Program Register supports the HPV vaccination program by providing information to consumers and providers about incomplete courses as well as estimates of vaccination coverage by age and area. Future monitoring of vaccine effectiveness will be facilitated by cross-linking to Pap test registries. Additional keywords: genital warts, monitoring, papillomavirus. Background Two prophylactic human papillomavirus (HPV) vaccines are currently registered worldwide, the bivalent vaccine Cervarix ® (GSK, Uxbridge, UK) protecting against the high-risk HPV types 16 and 18 that are responsible for ~70% of cervical cancers, 1,2 and the quadrivalent vaccine Gardasil ® (Merck, New Jersey, USA) that also protects against HPV types 6 and 11, which are detected in ~90–95% of genital warts. 3 Both prophylactic HPV vaccines are highly efficacious at preventing persistent infection with, and cervical lesions due to, the targeted HPV types 16 and 18. 4,5 Some cross-protection for other high- risk HPV types has also been demonstrated, particularly for the bivalent vaccine. 6–8 HPV vaccines have now been recommended in over 13 European countries, Australia, Canada and the USA for inclusion in their nationally funded vaccination programs. 9 Many more countries have approved the vaccines for use on demand and are considering the vaccines for public funding within their immunisation programs. There is substantial variation in the target age groups between currently funded vaccination programs. As HPV vaccines are prophylactic, they are most effective when administered to non- sexually active pre-adolescent females (i.e. those who have not been exposed to HPV). Depending on a range of considerations, including cost-effectiveness, local data about the age of sexual debut, delivery strategies and resources, the target age groups vary from pre-adolescent females, e.g. 11–12 year olds 10,11 through to ‘catch-up programs’ for 18–26 year olds. While both Canada and the USA recommend vaccination through to the age of 26 years (the oldest age included in the pre- licensure vaccine trial population), to date, only Australia has implemented a nationally funded vaccination catch-up program for 18–26 year old women. 9,12 HPV vaccination coverage: definition, rationale and requirements Vaccination coverage is defined as the proportion of the target population that has received the complete scheduled vaccination course. 13 The accurate measurement of vaccination coverage is critical because it provides an indicator of the proportion of the target population vulnerable to the vaccine preventable disease, as well as information about the performance of the vaccine delivery program and broader health system. 13 In general, modelling studies of the vaccine impact have suggested that programs should aim for (three-dose) HPV vaccination coverage rates of 80% or greater to ensure maximum population protection. 14 In older adolescents, vaccination coverage rates alone will not provide an accurate assessment of the proportion protected from cervical cancer (even just those due to the high-risk HPV types 16 and 18 covered by the current vaccines). HPV infection rates peak following the onset of sexual activity, 2 meaning that a significant proportion of sexually active females will have already been exposed when vaccinated and therefore remain susceptible to the consequences of persistent HPV infection. The ongoing method for cervical screening in countries that have introduced the HPV vaccine is presently a key policy consideration. HPV vaccine coverage rates in different age cohorts will provide relevant information on the cost- effectiveness of future alternative screening approaches. The provision of different screening pathways for individuals according to their vaccination history is highly unlikely to be CSIRO PUBLISHING Review www.publish.csiro.au/journals/sh Sexual Health, 2011, 8, 171–178 Ó CSIRO 2011 10.1071/SH10001 1448-5028/11/020171