Epidemiology of Herpes Zoster in the pre-vaccination era: establishing the baseline for vaccination programme’s impact in Spain

BACKGROUND: Herpes zoster (HZ) affects 1 in 3 persons in their lifetime, and the risk of HZ increases with increasing age and the presence of immunocompromising conditions. In Spain, vaccination guidelines were recently updated to include the recommendation of the new recombinant zoster vaccine (RZV) for certain risk groups. AIM: To describe the epidemiology of HZ-related hospitalisations in Spain in order to prioritise vaccination recommendations and define a baseline to monitor the effectiveness of vaccination policies. METHODS: Retrospective study using the National Health System’s Hospital Discharge Records Database, including all HZ-related hospitalisations from 1998 to 2018. RESULTS: The 65,401 HZ-related hospitalisations, corresponded to an annual mean hospitalisation rate of 6.75 per 100,000 population. There was an increasing trend of HZ hospitalisations over the study period. This rate was higher in males and older age groups, particularly over 65 years. Comorbidities with higher risk of readmission were leukaemia/lymphoma (RR 2.4; 95% CI: 2.3–2.6) and solid malignant neoplasm (RR 2.2; 95% CI: 2.1–2.4). Comorbidities associated with higher risk of mortality were leukaemia/lymphoma (RR 2.9; 95% CI: 2.7–3.2), solid malignant neoplasm (RR 2.9; 95% CI: 2.7–3.1) and HIV infection (RR 2.2; 95% CI: 1.8–2.7). CONCLUSION: Of all patients hospitalised with HZ, those with greater risk of mortality or readmission belonged to the groups prioritised by the current vaccination recommendations of the Spanish Ministry of Health. Our study provided relevant information on clinical aspects of HZ and established the base for future assessments of vaccination policies.