Relationship between shingles and coronavirus disease 2019: a self-controlled case series study

Background Although some studies suggest an increased risk of shingles following coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, no research has examined this relationship in real-world clinical settings. We aimed to investigate the association between shingles and COVID-19 by using a Japanese inpatient and outpatient claims database. Methods We identified patients with COVID-19 from 1 January 2020 to 30 January 2023 by using a Japanese inpatient and outpatient claims database. We also identified those who developed shingles and received antiviral drugs within 90 days before or after their COVID-19 diagnosis. Using self-controlled case series methods, we evaluated the relationship between shingles and COVID-19. We calculated the incidence rate ratio (IRR) [95% confidence interval (CI)] for shingles during the buffer period (days –35 to –7), pre-exposure period (days –6 to 0), and risk periods of the first and second, third and fourth, and fifth and sixth weeks following COVID-19 infection compared with a control period outside these intervals. Results Among 399 381 patients with COVID-19, 558 were diagnosed with shingles. The IRR was significantly elevated during the first and second (5.1, 95% CI 3.9–6.6), third and fourth (1.7, 95% CI 1.2–2.5), and fifth and sixth weeks (1.5, 95% CI 1.0–2.3) compared with a control period. Conclusion This study of a Japanese inpatient and outpatient database reveals a relationship between shingles and COVID-19, indicating that shingles may be a characteristic of the virus and highlighting the need for varicella-zoster vaccination alongside SARS-CoV-2 in the COVID-19 era.