RT Journal Article SR Electronic T1 Mental health in the second year of the COVID-19 pandemic: protocol for a nationally representative multilevel survey in Serbia JF BMJ Open JO BMJ Open FD British Medical Journal Publishing Group SP e053835 DO 10.1136/bmjopen-2021-053835 VO 11 IS 9 A1 Nadja P Marić A1 Ljiljana B Lazarević A1 Ljiljana Mihić A1 Milica Pejovic Milovancevic A1 Zorica Terzić A1 Oliver Tošković A1 Jovana Todorović A1 Olivera Vuković A1 Goran Knezevic YR 2021 UL http://bmjopen.bmj.com/content/11/9/e053835.abstract AB Introduction The COVID-19 pandemic is likely to have a prolonged impact on mental health (MH); however, the long-term MH effects of the COVID-19 pandemic remain unknown. The Serbian national survey—CoV2Soul.RS—was launched to document the MH status of the Serbian population following the COVID-19 pandemic and to contribute to an international evidence base about MH prevalence rates during different phases of the pandemic.Methods and analysis This cross-sectional study was designed to collect a nationally representative sample (N=1200; age 18–65 years; estimated start/end—June/November 2021) using multistage probabilistic household sampling. Trained staff will conduct in-person diagnostic interviews. A battery of self-report instruments will be administered to assess the quality of life (QoL), general distress and associated protective and harmful psychological and societal factors. Analyses will be conducted to delineate the prevalence rates of MH disorders, how MH conditions and QoL vary with respect to sociodemographic variables, personality, health status and traumatic events during the COVID-19 pandemic, and to test how these relations depend on geographical region. Moreover, this study was designed to explore mechanisms linking personality and the perception of pandemic consequences and associated distress. Prevalence rates of MH disorders will be calculated using descriptive statistics. For additional analyses, we will use correlations, analysis of variance and regression analyses. The hierarchical structure of the data will be explored using multilevel random coefficient modelling. Structural equation modelling will be used to investigate the indirect effects of personality on distress through relevant variables.Ethics and dissemination Ethical Committees of the Faculty of Medicine (1322-VII/31) and Faculty of Philosophy in Belgrade (02-33/273) and Faculty of Philosophy in Novi Sad (05-27, br.893/1) approved the protocol. Only respondents able to provide informed consent will participate in the study. Research reports will be submitted to peer-reviewed journals and the results will be placed on the website www.cov2soul.rs to be available to funders, researchers, policy-makers and interested laypeople, and will be advertised through social media.Trial registration number NCT04896983.