Association between live herpes-zoster vaccine and stroke risk: A population-based nested case-control study

Area of Science:

• Epidemiology
• Vaccinology
• Neurology

Background:

• Limited and inconsistent evidence exists on shingles vaccination's impact on stroke risk, especially intracerebral hemorrhage (ICH).
• Herpes zoster, commonly known as shingles, can have systemic implications beyond skin manifestations.
• Understanding vaccine-induced protection against major cerebrovascular events is crucial for public health.

Purpose of the Study:

• To investigate the association between zoster live vaccine (ZVL) and the risk of overall stroke and its subtypes.
• To analyze how the protective effect of ZVL against stroke varies with time since vaccination.
• To explore potential modifications of the ZVL-stroke association by age and sex.

Main Methods:

• Population-based nested case-control study utilizing data from Israel's largest healthcare provider (2015-2023).
• Inclusion of individuals aged 50+; stroke cases were matched with controls on age, sex, sector, and index date.
• ZVL exposure defined by prior prescription fill; adjusted odds ratios (OR) calculated.

Main Results:

• ZVL was associated with significantly reduced odds of overall stroke (OR 0.65), ischemic stroke (OR 0.65), and ICH (OR 0.64).
• Protective effect waned over time: OR 0.56 within 2.5 years, 0.71 (2.5-5 years), and 0.81 (>5 years).
• Stronger protection observed in individuals <65 years and males; interaction P-values <0.05.

Conclusions:

• Zoster live vaccine (ZVL) demonstrates a protective association against both ischemic stroke and intracerebral hemorrhage (ICH).
• The vaccine's protective benefit against stroke decreases progressively after vaccination.
• Males and younger individuals (<65 years) appear to derive greater stroke risk reduction from ZVL.