OBJECTIVE The objective of this study was to assess the benefits and risks of a lockdown in Belgium, with focus on mental health. Consequently, projecting the cost effectiveness of remedial measures.METHODS For benefits; in estimating health savings, we compared Belgium (lockdown) and Sweden (lockdown-light) for COVID-19 related deaths, peak intensive care unit load and peak hospitalisations load. We also calculated the years of life lost (YLL). For risks; we assessed the mental health and wellbeing, using the most common dimensions: anxiety and depression. GAD-7 and PHQ-9 scores were extracted from a survey and compared to a similar representative survey in 2018. Disability-adjusted life years (DALYs) were calculated for and we assessed non-COVID-19 related-deaths from excess mortality. Cost-utility analysis was performed with a 1-year time horizon. Hence, considering the Quality-adjusted Life Years (QALYs), Incremental Cost-effectiveness Ratio (ICER) and the potential impact providing adequate treatment compared to standard care.RESULTS Lockdown versus lockdown-light gave no COVID-19 related benefits. COVID-19 related risks during lockdown saw an increase of 4,231 deaths; 667 extra ICU admissions on peak day, 3213 extra hospital admissions on peak day and 140 extra non-COVID-19 related deaths. Additionally, 140 extra deaths occured due to a non-COVID-19 cause. 1,034,365 (9,0%) of Belgian population reported increased anxiety and/or depression. Risk-benefit analysis; COVID-19 related deaths yielded an extra 3,145 YLL, total psychological burden of 104,515 (74,025-139,762) DALYs and the total loss of societal value is considered between €3.0 billion and €5.6 billion. Cost-utility analysis; ICER for psychological treatment for depression was €11,510/QALY gained. In total psychotherapy could create 181,714 (34,134-213,654) QALYs and a 1 year net benefit of € 5.2 billion.CONCLUSION We found no evidence that a lockdown versus lockdown-light results in less COVID-19 related mortality and morbidity. The Belgian lockdown created an obvious +104,515 (74,025-139,762) DALYs psychological burden in Belgium. Adequate investment in psychological help would provide individual relief and may improve a person’s immunological response. Also, within a 1-year time horizon, taking into account the loss of value in healthy functioning people, the net benefit is €0.9 billion.