AIMS: This study aims to describe the mean trajectories of depression, anxiety and stress symptoms among Swedish university students before and during the second and third waves of the COVID-19 pandemic.

METHODS: We recruited 1835 participants in September 2020, of whom 81% provided follow-ups in December 2020-January 2021 and 77% provided follow-ups in March-April 2021. The short-form Depression, Anxiety and Stress Scale was used to measure mental health symptoms. Generalized estimating equations were used to estimate the mean differences in symptom levels over the three time periods.

RESULTS: Compared with September, mean depression was 0.91 points of 21 higher (95% confidence interval (CI) 0.70-1.13) in December 2020-January 2021 and 0.66 points higher (95% CI 0.43-.88) in March-April 2021. Anxiety levels were 0.20 points higher (95% CI 0.05-0.34) in December 2020-January 2021 and 0.17 points higher (95% CI 0.02-0.33) in March-April 2021. Stress levels were 0.21 points higher (95% CI 0.00-0.41) in December 2020-January 2021 and 0.16 points lower (95% CI -0.38 to 0.05) in March-April 2021.

CONCLUSIONS: Our results indicate relatively stable levels of mental health among Swedish university students during the second and third waves of COVID-19 compared with before the second wave. Mean depression symptom scores increased slightly, but the importance of this small increase is uncertain.