1  Introduction
From COVID-19, MERS and SARS to H1N1, Zika and Ebola, people around the world have been facing rampant waves of infectious diseases. New pandemics are anticipated to occur at an increasing frequency (Wolfe, 2011). Yet the current understanding of how an outbreak influences people's psychological well-being is incomplete. Much prior research has focused on well-being differences across, for example, gender (Wood, Rhodes, and Whelan, 1989), age (Steptoe, Deaton, and Stone, 2015), degrees of social connectedness (Myers, 1999), income levels (Kahneman and Deaton, 2010), individual dispositions (Diener and Seligman, 2002), and consumption patterns (Dunn, Aknin, and Norton, 2008). However, relatively little is known about how an increasingly common phenomenon—epidemic outbreak—impacts emotional well-being (Lu et al., 2020, Zhang et al., 2020). Even less is known about the factors that may worsen or protect emotional well-being during an outbreak. Identifying these factors is critically important, as they inform policies and interventions aimed at protecting people's psychological well-being in the age of pandemics.
We sought to add to this understanding through two large-scale nationwide surveys conducted in China immediately before versus during the coronavirus outbreak. We found that the onset of the epidemic in China led to a 74% decline in overall emotional well-being. Individuals who were residing near the epicenter of the outbreak, of an older age, or married, experienced a steeper decline in emotional well-being. This suggests that factors associated with, respectively, the likelihood of contracting the disease, extent of potential harm, and relational issues are moderators of well-being deterioration during an epidemic. Perhaps more importantly, we found that, during the coronavirus outbreak, individuals’ perceived level of knowledge about coronavirus infection was a stronger “protector” of their emotional well-being than the actual amount of knowledge they possessed. We propose that this is because a higher level of perceived knowledge can lead to a stronger sense of control, which in turn protects emotional well-being during an outbreak. This proposition was supported by the results of our analyses: sense of control was a mediator of the impact of perceived knowledge on emotional well-being (even after controlling for actual knowledge as well as demographic and economic variables). The finding thus suggests that factors boosting sense of control can alleviate the detrimental effect of an epidemic outbreak on emotional well-being.