Incidence of Guillain–Barré syndrome in South Korea during the early COVID-19 pandemic

OBJECTIVES: Guillain–Barré syndrome (GBS) is an immune-mediated polyradiculoneuropathy, often triggered by infection. We aimed to investigate how the incidence of GBS changed in the early stages of the coronavirus 2019 (COVID-19) pandemic when nationwide infections declined due to non-pharmaceutical interventions. METHODS: We conducted a nationwide population-based retrospective GBS cohort study using data from the Health Insurance Review and Assessment Service of Korea. Patients with new-onset GBS were defined as those who were first hospitalized between 1 January 2016 and 31 December 2020 with an International Classification of Disease, 10th Revision code, for GBS (G61.0) as a primary diagnosis. The incidence of GBS in the pre-pandemic years (2016–2019) was compared with that in the first pandemic year (2020). Nationwide epidemiological data for infections were collected from the national infectious disease surveillance system. A correlation analysis was performed to determine the incidence of GBS and nationwide trends of various infections. RESULTS: Overall, 3,637 new-onset GBS cases were identified. The age-standardized incidence of GBS in the first pandemic year was 1.10 (95% confidence interval, 1.01–1.19) per 100,000 persons. Compared to the first pandemic year, the incidence of GBS during the pre-pandemic years (1.33–1.68/100,000 persons/year) was significantly higher, with incidence rate ratios of 1.21–1.53 (P < 0.001). Nationwide cases of upper respiratory viral infections were significantly reduced in the first pandemic year; however, Campylobacter infections peaked in the summer of the pandemic. The nationwide epidemiology of parainfluenza virus, enterovirus, and Campylobacter infections correlated positively with GBS incidence. CONCLUSION: The overall GBS incidence decreased in the early stages of the COVID-19 pandemic, which can be attributed to the dramatic reduction in viral illnesses due to public measures.