Abstract
Aim:
The aim of this study was to investigate the possible impact of the Covid-19 pandemic on general health, mental well-being, and experiences of control compared to pre-pandemic populations. Our hypotheses were that we would observe a significantly lower level of psychological well-being and general health in the 2020 sample compared to the pre-pandemic samples, and that we would observe younger age groups to be the most affected.

Method:
Two representative Danish populations (2016, n = 1656) and (2017, n = 3366) were compared to a representative Danish population (2020, n = 1538) sampled during the first lockdown in May 2020. Two-tailed tests of proportions were used to investigate possible differences between samples in proportions reporting poorer mental well-being measured by 5-item World Health Organization Well-Being Index, general health, and internal locus of control.

Results:
Younger men (aged 18–24) and younger women (aged 18–44) as well as elderly women (aged 65–74) reported lower mental well-being during the early phase of the pandemic compared to the population from 2016. Both women and men in 2020 reported significantly lower levels of internal locus of control compared to the 2017 sample. This was especially true for younger men and women. There were no statistically significant differences in general health between populations.

Discussion:
This study partly supports the hypothesis that the Covid-19 pandemic affected mental well-being negatively among younger persons. However, longitudinal studies are needed to investigate possible long-term effects of the pandemic on mental health and well-being. Further, qualitative studies are needed to investigate the in-depth consequences of Covid-19.