The impact of the National Shingles Vaccination Program on the epidemiology of herpes zoster among adults ≥ 60 years in Victoria, Australia

Introduction In November 2016, Australia recommended herpes zoster (HZ) vaccination for adults aged >= 60 years and implemented a National Shingles Vaccination Program (NSVP) offering free HZ vaccination to adults aged 70-79 years. This study investigated trends in HZ epidemiology among Victorian adults aged >= 60 years and the impact of the NSVP in this population. Methods We conducted epidemiological analyses of routinely collected HZ surveillance data for Victorian adults aged >= 60 years who were notified as having a HZ illness or vaccination between 2012 and 2021. Annual incidence rates are presented for vaccinations, case notifications, emergency department presentations, hospitalisations and deaths by five-year age groups. Age-specific incidence rate ratios are calculated comparing the period prior to (1 January 2012 to 31 October 2016) and following (1 November 2016 to 31 December 2021) NSVP implementation. Results HZ vaccination rates were highest among those eligible to receive free vaccination (70-79 years), but appear to have plateaued across all age groups and remained below full coverage. Incidence rate ratios showed a statistically significant increase (p < 0.01) in HZ notifications across all age-groups. Emergency presentations and hospitalisations showed a statistically significant decline (p < 0.05) among the 70-79 year old age groups; however, these rates remained consistent or increased among other age groups for whom vaccination is recommended. Mortality rates declined, particularly among those aged 85+ years. Discussion HZ continues to cause significant disease among the older adult population in Victoria. The findings of this study suggest the NSVP has led to some changes in the epidemiology of HZ among the 70-79 years old age group in Victoria; however, there is less evidence that it has influenced other age groups for whom vaccination is recommended. An evaluation of the NSVP and epidemiology of HZ at a national level is required to identify strategies to improve vaccination coverage among the target populations.