Healthcare workers’ heterogeneous mental-health responses to prolonging COVID-19 pandemic: a full year of monthly follow up in Finland

BACKGROUND: The COVID-19 pandemic strained healthcare workers but the individual challenges varied in relation to actual work and changes in work. We investigated changes in healthcare workers’ mental health under prolonging COVID-19 pandemic conditions, and heterogeneity in the mental-health trajectories. METHODS: A monthly survey over a full year was conducted for employees of the HUS Helsinki University Hospital (n = 4804) between 4th June 2020 to 28th May 2021. Pandemic-related potentially traumatic events (PTEs), work characteristics (e.g., contact to COVID-19 patients), local COVID-19 incidence, and demographic covariates were used to predict Mental Health Index-5 (MHI-5) and Insomnia Severity Index (ISI) in generalized multilevel and latent-class mixed model regressions. RESULTS: Local COVID-19 log-incidence (odds ratio, OR = 1.21, with 95% CI = 1.10–1.60), directly caring for COVID-19 patients (OR = 1.33, CI = 1.10–1.60) and PTEs (OR = 4.57, CI = 3.85–5.43) were all independently associated with psychological distress, when (additionally) adjusting for age, sex, profession, and calendar time. Effects of COVID-19 incidence on mental health were dissociable from calendar time (i.e., evolved in time) whereas those on sleep were not. Latent mental-health trajectories were characterized by a large class of “stable mental health” (62% of employees) and minority classes for “early shock, improving” (14%) and “early resilience, deteriorating” mental health (24%). The minority classes, especially “early shock, improving”, were more likely to live alone and be exposed to PTEs than the others. CONCLUSIONS: Healthcare workers faced changing and heterogeneous mental-health challenges as the COVID-19 pandemic prolonged. Adversity and mental ill-being may have accumulated in some employees, and factors like living arrangements may have played a role. Knowledge on employees’ demographic and socioeconomic background, as well as further research on the factors affecting employees’ resilience, may help in maintaining healthy and efficient workforce in the face of a prolonging pandemic. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12888-022-04389-x.