Background: The incidence of stroke, transient ischaemic attack (TIA) and myocardial infarction (MI) increases following Herpes Zoster. Other vaccine preventable diseases including influenza and pneumococcal infection have also shown increased subsequent risk of cardiovascular disease and guidelines recommend immunisation of at-risk groups. Australia introduced the National Shingles Immunisation Program in November 2016. Adults aged 70-79 are offered immunization with zoster vaccine (Zostavax) free of charge. Zostavax has shown a reduction in incidence of Herpes Zoster by approximately half. Therefore, the aim of this study was to investigate if Herpes Zoster immunisation reduces the risk of subsequent cardiovascular events.
Method: A retrospective matched cohort study was performed using the National Prescribing Service MedicineInsight database. MedicineInsight is an Australian primary care record containing anonymized demographic and medical encounter data for 2.3 million active patients from 419 general practices across all states and territories. It represents approximately 10% of Australian general practice encounters. Every adult patient who had the Herpes Zoster vaccine between 31st October 2016 to 30th June 2020 were matched by age and sex to two unvaccinated individuals. Univariable analysis for time to stroke, TIA and MI by Herpes Zoster vaccination will be examined using Kaplan-Meier curves and logrank test. Secondary outcomes include time to herpes zoster and herpes zoster opthalmicus. Multivariate analysis will be performed using Cox proportional regression models. Analysis will be conducted using SAS software version 9.4.
Results: Data analysis is currently in progress.
Discussion/Implications for Practice: Despite evidence of increased risk between Herpes Zoster and subsequent cardiovascular disease, there is minimal literature investigating if immunisation can reduce this risk. Findings will inform current immunisation policies and could lead to more targeted vaccination strategies focusing on patients with higher cardiovascular risk.