Pandemic Fatigue: Measurement, Correlates, and Consequences Lau Lilleholt1, Ingo Zettler1, Cornelia Betsch2,3, and Robert Böhm1,4,5 1Department of Psychology, University of Copenhagen, Øster Farimagsgade 2A, 1353, Copenhagen, Denmark; 2Media and Communication Science, University of Erfurt, Norhäuser Str. 63, 99089 Erfurt, Germany; 3Center for Empirical Research in Economics and Behavioural Sciences (CEREB), University of Erfurt, Norhäuser Str. 63, 99089 Erfurt, Germany; 4Department of Economics, University of Copenhagen, Øster Farimagsgade 5, 1353, Copenhagen, Denmark; 5Copenhagen Center for Social Data Science (SODAS), University of Copenhagen, Øster Farimagsgade 5, 1353, Copenhagen, Denmark *Correspondence to: [email protected] 1 Abstract With no effective treatment or vaccine widely available, most national COVID-19 response strategies have relied on people’s willingness to comply with health-protective behaviours and behavioural restrictions. Despite generally high levels of public compliance, several countries have reported a recent upsurge in the number of people who no longer sufficiently adhere to restrictions or keep themselves informed about COVID-19. This developing trend has been attributed to Pandemic Fatigue. Using quota-representative survey data from Denmark and Germany (overall n = 12,191), we introduce a psychometrically sound measure of Pandemic Fatigue, show who experiences it, identify related emotions and perceptions, and shed light on the relation between Pandemic Fatigue and four COVID-19-related health-protective behaviours. Further, based on a preregistered online experiment with US participants (n = 1,584), we establish a causal link between Pandemic Fatigue and people’s intention to comply with recommended heath-protective behaviours. 2 Introduction In an attempt to curb the spread of the Coronavirus disease 2019 (COVID-19), governments and health authorities across the globe have both recommended and mandated various health-protective measures, such as mask wearing, physical distancing, and self-isolation. While these and other measures are effective in constraining the COVID-19 pandemic1–5, they require tremendous economic and psychological sacrifices on the part of the public6,7 and ultimately depend on people’s constant willingness to follow guidelines and restrictions. Despite a generally high level of public support for national COVID-19 response strategies8, several countries have reported a growing number of people who no longer sufficiently adhere to restrictions and who have progressively decreased their efforts to keep themselves informed about the pandemic8. This developing trend could potentially undermine national and global efforts to control the spread of the virus, even after vaccination becomes more widely available. In fact, as the full immunization of populations against COVID-19 could still take several months9 or even years, it will remain important to maintain high public compliance with the recommended health-protective behaviours to curb the spread of the disease, minimize the risk of mutations, and, ultimately, save lives. According to the World Health Organization (WHO), the recent upsurge in noncompliance with COVID-19-related health-protective measures is likely to be a product of Pandemic Fatigue8. WHO has proposed that Pandemic Fatigue can be understood ‘as demotivation to follow recommended protective behaviours, emerging gradually over time and affected by a number of emotions, experiences and perceptions’ (p. 7)8. Being a latent phenomenon that is not directly observable, Pandemic Fatigue is believed by WHO to express itself on the behavioural level ‘through an increasing number of people not sufficiently following recommendations and restrictions, [and] decreasing their effort to keep themselves informed about the pandemic’ (p. 7)8. 3 Indeed, some research suggests that people’s awareness of the pandemic may change over time and, in turn, affect disease spread10–12. Importantly, however, Pandemic Fatigue has thus far solely been derived from observations of behaviour, and, given this lack of direct measurement, some scholars have questioned the importance or even existence of Pandemic Fatigue, since corresponding behavioural patterns could also be explained by other factors (e.g., decreased perceived threat from the disease). In sum, it remains unclear how to measure and quantify Pandemic Fatigue, who is likely to experience it, what emotions and perceptions relate to it, and how much of an impact it has on people’s behaviour. It is thus crucial to conceptualize Pandemic Fatigue indiviudally, disentangling it from its correlates and consequences. Herein, we present such a conceptualization and introduce a corresponding brief and psychometrically sound measure of Pandemic Fatigue—the Pandemic Fatigue Scale (PFS). Using this measure in a series of 13 cross-sectional, nationally representative surveys conducted in Denmark and Germany (overall n = 12,191), we (i) investigate who experiences Pandemic Fatigue, (ii) identify related emotions and perceptions, and (iii) shed light on the relation between Pandemic Fatigue and four important COVID-19 related health-protective behaviours: physical distancing, hygienic behaviour, mask wearing, and information seeking. In addition, a preregistered online experiment conducted with participants from the US (n = 1,584) establishes a causal link between Pandemic Fatigue and people’s intention to follow these behaviours. Taken together, we present a clear conceptualization and measurement of Pandemic Fatigue, disentangling this construct from pure observations of behavioural patterns, which have otherwise—without any formal testing or research —simply been attributed to Pandemic Fatigue. The conceptualization and corresponding brief measure of Pandemic Fatigue introduced herein allows for the identification of fatigue groups for targeted interventions as well as testing how Pandemic Fatigue might be reduced—not only during the COVID-19 pandemic but also in upcoming future pandemics. 4 Our cross-sectional survey data comes from two COVID-19 Snapshot MOnitoring (COSMO) projects13. Since March 2020, COSMO has assessed citizens’ knowledge, perceptions, emotions, and behavioural reactions related to COVID-19 across several countries, including Denmark14 and Germany15, using a mixture of weekly, biweekly, and monthly cross-sectional and panel surveys. The COSMO surveys also collect sociodemographic information, including age, gender, education, employment, and health status. The Danish COSMO surveys further assess people’s basic personality characteristics in terms of the HEXACO traits (Honesty-Humility, Emotionality, Extraversion, Agreeableness vs. Anger, Conscientiousness, and Openness to Experience)16, which are related to a wide array of humans’ thoughts, feelings, and behaviours17, including health-protective behaviours18. More specifically, herein, we use data from seven biweekly measurement points (October 19, 2020–January 17, 2021) of the Danish cross-sectional COSMO survey and six weekly measurement points (27 October, 2020–11 November, 2020 and 22 December, 2020–13 January, 2021) of the German cross-sectional COSMO survey, in which Pandemic Fatigue was assessed with the newly developed PFS. During this period, both Denmark and Germany were experiencing a second wave of COVID-19, during which new and stricter restrictions were imposed after public life had been gradually reopened following the first complete lockdown in early spring 2020. As such, this time period is the perfect setting for studying Pandemic Fatigue, as Danes and Germans alike had already been struggling with COVID-19 for quite some time and were facing yet another highly challenging pandemic-related period—with great uncertainty regarding its length and hardship. Results Development and validation of the Pandemic Fatigue Scale (PFS) We conceptualized Pandemic Fatigue to represent a general feeling of demotivation towards following COVID-19 related health-protective behaviours and staying informed about the development of the pandemic. We first generated an item pool, which we adapted and reduced to 10 5 items in various internal feedback loops. The finally chosen 10 items were then administered in calendar week 49 (19–25 October) of 2020 in the Danish cross-sectional COSMO survey (n = 923). The 10-item version of the PFS is provided in Table S1. To explore the factor structure of the PFS, we conducted an ordinary least squares exploratory factor analysis with oblique factor rotation19. In order to determine the number of factors to extract, we considered the scree test20, Very Simple Structure criterion21, and Velicer’s Minimum Average Partial criterion22, which combined indicated that either one or two factors would best reflect the data (Figure S1 and Table S2). Results from the exploratory factor analysis showed that a one-factor model did not fit the data well (RMSR = .07, RMSEA = .13, TLI = .84), whereas a two-factor model yielded an acceptable fit (RMSR = .02, RMSEA = .05, TLI = .98). Assessing the content of the items pertaining to each factor, the first factor, consisting of three items, represents what we have termed ‘Information Fatigue’ (i.e., being tired of hearing about COVID-19), and the second factor, consisting of seven items, represents what we have termed ‘Behavioural Fatigue’ (i.e., feeling demotivated and strained from fighting COVID-19). As our goal was to develop a brief measure of Pandemic Fatigue that could easily be administered in