Abstract
OBJECTIVES: The COVID-19 pandemic affected mental health worldwide, including obsessive-compulsive symptoms (OCS) and, specifically, contamination-related OCS (C-OCS). This study aimed to map these symptoms' trajectories over four years, thus providing the longest known observational timeline of OCS during and after a pandemic. Longitudinal data on OCS spanning this period offer the rare opportunity to examine how external crises intersect with symptom trajectories over time, offering insights into patterns of symptom fluctuation and remission. DESIGN: We conducted a longitudinal panel study with 1,214 participants from the German general population assessed at the onset of the pandemic (T1), three months later (T2) and 12 months after T1 (T3), followed by annual assessments (T4, T5, T6). METHODS: We measured OCS and C-OCS using the Obsessive-Compulsive Inventory-Revised and calculated mixed-effect models for repeated measurements. RESULTS: Analyses indicated a significant but declining increase in OCS from T1 to T2, T3 and T4 (d = -.11 to -.05), with symptoms returning to baseline levels during annual assessments at T5 (d = -.02) and T6 (d = .03). By contrast, C-OCS consistently and significantly decreased at each timepoint, indicating a steady reduction in symptom severity over the assessment period (d = .12 to .46). CONCLUSION: The initial OCS spike reflects stress and uncertainty in the population, while the steady C-OCS improvement may be due to the normalization of hygiene practices over time. These patterns highlight the impact of pandemic-related health management on C-OCS. Factors affecting the general population that are linked to these symptoms can contribute to an individual's deterioration (for example promotion of hygiene practices). Understanding these dynamics contributes to a better understanding of C-OCS and associated risk factors.