BackgroundEarly in the COVID-19 pandemic, adherence to non-pharmaceutical interventions is especially critical to controlling disease spread. Understanding the factors that influence the initial demotivation to comply with public health guidance can enable the design of more effective interventions for future epidemics.MethodsWe collected participant-reported data on psychological distress and the number of weekly contacts with non-household members across six surveys administered between April and September 2020 among two cohorts: (1) families with children and (2) adults aged 50 years and older. We then used marginal structural models to examine the time-varying effect of distress on future interactions with non-household members as a measure of pandemic fatigue.ResultsAmong families with children, each unit increase in distress at the beginning of the study resulted in a 9% increase in non-household contacts (RR: 1.09; 95% CI: 1.03 to 1.16), but the effect declined with each additional week by 1.8% (ratio of RR: 0.982; 95% CI: 0.971 to 0.993). For adults over age 50, the relationship was reversed. Increasing distress led to a 7.2% decline in contacts (RR: 0.928; 95% CI: 0.863, 0.998) at the beginning of the study, but this effect increased by 1.0% with each additional week (ratio of RR: 1.01; 95% CI: 1.00 to 1.02).ConclusionsWe observed that the initial effect of psychological distress on adherence to recommendations to reduce non-household contacts and the change in the effect of distress over time (pandemic fatigue) differed between our two cohorts. Response strategies among younger/lower risk populations may be more effective when focused on broader implications of community transmission, while response strategies among older/higher risk populations may be more effective if they focus on increasing resilience and fostering safe coping strategies.