BACKGROUND: Addressing the effects of non-compliance with health-related recommendations in pandemics is needed for informed decision-making. This longitudinal study investigated the effects of non-compliance on mental health and academic self-efficacy among university students in Sweden.

METHODS: Baseline assessments were conducted in May 2020, with follow-ups after 5 and 10 months. Students (n = 3123) from 19 universities completed online questionnaires covering compliance, mental health, and academic self-efficacy. Effects of non-compliance were estimated using causal inference and multilevel multinomial regression.

RESULTS: Non-compliant students constituted a minority, but their proportion increased over time. Regarding mental health and academic self-efficacy, few differences were observed between compliant and non-compliant students. When differences were identified, non-compliant students experienced fewer negative effects on mental health and academic self-efficacy than compliant students.

CONCLUSION: The findings may suggest that non-compliance may have involved a trade-off between increased individual freedom and mitigating negative outcomes. Addressing the research gap on non-compliance effects is crucial for informed decision-making and promoting the common good. This may guide strategies balancing individual autonomy and collective well-being during future pandemics.

PRE-REGISTRATION: Center for Open Science (OSF), https://accounts.osf.io/login?service=https://osf.io/37dhm/ .