Risk of anxiety disorders and insomnia following COVID-19 vaccination

Objective: Despite extensive evaluations of potential adverse events related to COVID-19 vaccination, the risk of mental health outcomes following vaccination remains unclear. We evaluated the risk of anxiety disorders and insomnia associated with COVID-19 vaccination in Korea. Methods: We performed a self-controlled case series study using COVID-19 vaccination registration data from the Korea Disease Control and Prevention Agency and claims data from the National Health Insurance Service. This study included individuals over 18 who received their first COVID-19 vaccine between February 26 and September 30, 2021, and were subsequently diagnosed with anxiety disorders or insomnia. The risk intervals were defined as 1–7, 8–14, 15–21, and 22–42 days following vaccination, with the observation period extending to 365 days after the first dose. Incidence rate ratios (IRRs) were estimated using conditional Poisson regression by comparing outcome incidence in the risk and control windows, with adjustment for calendar month. Results: A total of 156,290 anxiety disorders cases and 250,704 insomnia cases were identified. The risk of anxiety disorders was elevated across all risk intervals with IRRs (95 % confidence intervals [CIs]) of 1.05 (1.03–1.08), 1.12 (1.10–1.15), 1.13 (1.10–1.15), and 1.09 (1.08–1.11), respectively. The risk of insomnia increased in all intervals except for days 1–7, with IRRs (95 % CIs) of 0.98 (0.96–1.00), 1.10 (1.08–1.12), 1.07 (1.06–1.09), and 1.13 (1.12–1.14). Conclusion: COVID-19 vaccination was associated with an increased risk of anxiety disorders and insomnia. These findings should be interpreted with caution in light of pandemic-related psychosocial stressors and changes in healthcare-seeking patterns.