Objectives: To assess the psychometric properties of the Coronavirus Information Overload scale (CovIO) and explore relationships between CovIO, its predictors and several health behaviours related to the COVID-19 pandemic, using Cancer Information Overload (CIO) scale results as a reference for comparison. Methods: 2003 participants representative of the French adult population answered a self-administered questionnaire over two waves of polling (N1(June 2020)= 1003, N2(January 2021)= 1000). Respondents were randomized to fill CovIO or CIO scale. Psychometric properties of scales were evaluated with Confirmatory Factor Analysis (CFA). Predictors were assessed using multivariate linear regression. Results: CovIO scale showed satisfactory psychometric properties (α=0.86, ω=0.86, RMSEA=0.050) without any measurement invariance issue. CovIO increased between waves of sampling and was significantly linked to education, health literacy and trust in institutions among other variables. A negative relationship between information overload and preventive behaviours was also observed. Conclusion: The CovIO scale is a valid tool for assessing COVID-19 information overload. The dynamical formation of information overload and links with theorised predictors, especially, health literacy are confirmed. Practice implications: Longitudinal designs could help better understand the potential detrimental effect of information overload and improving public health campaigns. Interventions to reduce the degree of overload are needed.