Mental health was not a priority in the initial management of the COVID-19 crisis. Attention to this problem arose later, and only after the first serious signs of increased psychological distress among the general population became apparent (e.g. a higher prevalence of depression, anxiety, post-traumatic stress, more widespread suicidal thoughts, increased domestic violence). Now that the crisis appears to be over, its impact on people's psychological wellbeing is still difficult to measure, evaluate, and address, but its side effects persist. Moreover, mental health problems have primarily been considered a consequence of the pandemic, but this neglects pre-existing factors that played a role in mitigating or exacerbating the impact the COVID-19 crisis had on the general population. Systematic data collection would provide insights into which groups have been most at risk of developing mental health problems and why, and, in the event of a future crisis, it would help to predict the differential impacts of policy measures. In addition, data collection would provide a basis for developing a prevention-oriented approach at the European level to facilitate the early detection and timely treatment of mental health issues.