The ZOster ecoNomic Analysis (ZONA) model (Fig. 5) was developed in MS Excel. It is a static multi-cohort Markov model. Cohorts are split into 5 age groups for people aged 50+ years (i.e., 50–59, 60–64, 65–69, 70–79, 80+). If the “50+ years combined” option is selected, the model assumes that all of the subjects in the 50–59, 60–64, 65–69, 70–79 and 80+ age cohorts are vaccinated, as in a one-off ‘catch-up’ campaign, at an age of 50, 60, 65, 70 and 80 y respectively. The model follows all subjects within a cohort over their remaining life-time from the year of vaccination with annual cycle lengths. As such all subjects remain in their initial cohort and all subsequent events are counted in that cohort only. Three different HZ vaccination strategies are compared; no vaccination (control), vaccination with ZVL, and vaccination with HZ/su. Within each vaccine arm/strategy, individuals can be fully compliant with the vaccine dosing schedule, partially compliant or not vaccinated at all, depending on the corresponding vaccine coverage and compliance rates assumed. An overview of the model structure is presented in Fig. 5. Transition probabilities between the health states HZ, natural death, HZ related deaths, recover, recurrent HZ,.. occur using an annual time step. PHN and NON-PHN complications are health states which occur within a HZ episode and as such occur within this annual time step. Probabilities of moving between health states are derived from Germany specific literature and are age-group specific.

Schematic overview of Markov structure – ZONA model. HZ: herpes zoster; PHN: postherpetic neuralgia.

In this analysis 3 age cohorts were considered, i.e., 50–59, 60–69 and 70+ years, i.e., combining results from the 60–64 and 65–69 cohorts and the 70–79 and 80+ cohorts, respectively, for presentation purposes. The age cohorts were selected to capture age-dependent differences in disease incidence, complications, outcomes, costs and potential public health decision making.
Free full text: Click here