OBJECTIVES: Herpes Zoster (HZ) and its complications such as postherpetic neuralgia (PHN) impose a considerable disease and economic burden in Italy. In February 2017, the updated National Immunization Plan (NIP) was approved, this includes HZ vaccination for everyone aged 65 years old. This study estimates the potential public health impact of introducing a two-dose candidate HZ adjuvanted subunit vaccine (HZ/su), submitted for approval, or a Zoster Vaccine Live-attenuated (ZVL).

METHODS: The ZOster ecoNomic Analyses (ZONA) model is a static, multi-cohort Markov model that followed all 65-year-old subjects over their remaining lifetime from the year of vaccination. To adapt the model to the Italian setting, a literature review was conducted to identify the inputs. Population statistics were derived from the national bureau for statistics and epidemiological inputs came from peer-reviewed articles. Vaccine characteristics were estimated from the respective clinical trials. To forecast the impact of vaccination in 2018, 20% coverage was assumed for both vaccines, as per the NIP, with a second-dose compliance of 70% for HZ/su. Scenario analyses will be performed around second-dose compliance.

RESULTS: Vaccinating 20% of the 726,337 individuals aged 65 years, HZ/su would prevent 11,948 HZ cases, 1,775 PHN cases and 1,004 of other complications compared to 4,677 HZ cases, 697 PHN cases and 393 of other complications avoided with ZVL over the population lifetime. The number needed to vaccinate (NNV) to prevent 1 HZ case for HZ/su was 13 compared to 32 for ZVL. The NNV to prevent 1 PHN case was 82 for HZ/su and 209 for ZVL, respectively.

CONCLUSIONS: This study predicts that the introduction of a HZ vaccination program in Italy could substantially reduce the burden of disease related to HZ. Introducing HZ/su to the 65-year-old population in Italy would avoid a greater number of HZ cases and its complications compared to ZVL.