Developing representations of a 'new' illness using the Common Sense Model: evolving COVID-19 illness representations and their associations with protective behaviours in the Scottish population.

Objective: There is a lack of research on how illness representations as represented in the Common Sense Self-Regulation Model (CS-SRM) emerge and develop. We aimed to describe the evolution of COVID-19 illness representations over time, and to explore associations with sociodemographic characteristics and protective behaviours.

Methods and measures: This study (June 2020 release from lockdown to February 2021 after vaccine roll-out) used 17 independently recruited cross-sectional cohorts. Telephone interviews with randomly selected Scottish adults (N_total = 8455) assessed illness representations and adherence to protective behaviours (physical distancing, wearing face covering, hand washing).

Results: Multivariable regression showed that beliefs in consequences and longer duration initially increased but later reduced. Overall females (Beta's = -.067-.226), older people (Beta's = .002-.014) and people from deprived areas (Beta's = -.200-.072) represented COVID-19 as more threatening and time did not change most of these associations. People who felt more threatened [F(9, 4587) = 55.746, p < .001, R² = .099] or believed COVID-19 was caused by lacking protective behaviours [F(8, 4804) = 59.738, p < .001, R² = .090] were more likely to adhere to protective behaviours. Believing not keeping distance as a cause was associated with adherence; this association strengthened over time.

Conclusion: Illness representations changed over time, mirroring increasing knowledge and improved medical management, but also reflecting population anxiety and sense of control. Sociodemographic differences may relate to social roles and vulnerability. Illness representations predicted protective behaviours.