Ambient temperature and herpes zoster risk in South Korea: A 14-year nationwide case-crossover study with 149,098...

Ambient temperature has been suggested as a potential trigger for herpes zoster (HZ), but individual-level evidence remains limited. We investigated the short-term association between ambient temperature and HZ onset using nationwide individual-level data.

A time-stratified case-crossover study was conducted using the National Health Insurance Service-National Sample Cohort of South Korea (2006-2019). Daily mean temperature was linked to 149,098 incident HZ cases among adults aged ≥ 20 years based on residential location. Conditional logistic regression estimated odds ratios (ORs) and 95% confidence intervals (CIs), adjusting for humidity, with exploration of lag structures and non-linear associations.

Higher daily mean temperature significantly increased HZ risk, peaking on the exposure day (OR per 1°C: 1.0046; 95% CI, 1.0028-1.0065). Cumulative effects were most evident within 2 days. Risks were more pronounced in adults aged ≥ 65 years and those with comorbidities, especially chronic kidney disease. Non-linear analysis showed an approximately linear, monotonically increasing trend between temperature and HZ risk, indicating a higher risk of HZ at warmer temperatures.

Elevated ambient temperature is an acute trigger for HZ. These findings highlight the vulnerability of elderly and chronically ill populations to thermal stress. Ambient temperature should be integrated into HZ prevention strategies, particularly considering the health impacts of climate change.