ABSTRACT
OBJECTIVE: The COVID-19 pandemic saw promotion of novel virus transmission-reduction behaviours, and discouragement of familiar transmission-conducive behaviours. Understanding changes in the automatic nature of such behaviours is important, because habitual behaviours may be more easily reactivated in future outbreaks and disrupting old habits may discontinue unwanted behaviours. DESIGN: A repeated-measures, multi-national design tracked virus-transmission habits and behaviour fortnightly over six months (Apr-Sept 2020) among 517 participants (age M = 42 ± 16y, 79% female). MAIN OUTCOME MEASURES: Within-participant habit trajectories across all timepoints, and engagement in transmission-reduction behaviours (handwashing when entering home; handwashing with soap for 20 seconds; physical distancing) and transmission-conducive behaviours (coughing/sneezing into hands; making physical contact) summed over the final two timepoints. RESULTS: Three habit trajectory types were observed. Habits that remained strong ('stable strong habit') and habits that strengthened ('habit formation') were most common for transmission-reduction behaviours. Erosion of initially strong habits ('habit degradation') was most common for transmission-conducive behaviours. Regression analyses showed 'habit formation' and 'stable strong habit' trajectories were associated with greater behavioural engagement at later timepoints. CONCLUSION: Participants typically maintained or formed transmission-reduction habits, which encouraged later performance, and degraded transmission-conducive habits, which decreased performance. Findings suggest COVID-19-preventive habits may be recoverable in future virus outbreaks.