In response to the coronavirus outbreak, people may experience anxiety, empathy, and prosocial willingness. However, the relationship between emotions, empathy, and prosocial behaviour is unknown. It is said that empathy is affected by moods and influences pro-sociality. Thus, how does an emergency change people’s empathy and prosocial willingness? We conducted a study with 1,190 participants before (N=520) and after (N=570) the coronavirus outbreak. We found that prosocial willingness decreased post-outbreak, maybe by the decreased empathy levels, in accordance with compassion fatigue theory. Trait empathy could affect prosocial willingness indirectly through the empathy level. News discriminability and distance from the outbreak epicentre played a role in the trait empathy change. Given how emergency health events influence emotion and the effects of personal traits on prosocial willingness, social media users and providers should understand the negative effects of information over-exposure on mental health during the outbreak.