Deterioration of mental health despite successful control of the COVID-19 pandemic in South Korea

South Korea was able to successfully control the spread of COVID-19 without nationwide lockdowns or drastic social distancing efforts, but pandemic-related psychological outcome of the general population remains unknown. We aimed to document the mental health outcome in relation to social factors during the pandemic. Between March and June 2020, 400 South Korean residents participated in an online study of depression, anxiety, stress, psychosis-risk and loneliness, as well as indices of social network, physical health and demographics. Clinical levels of depression, anxiety or stress were reported by 45% of the respondents, and psychosis-risk was present in 12.8%; a drastic increase above the base rate prior to the pandemic. Subjective feelings of loneliness, but not the size of the social network accounted for poor mental health. Women were especially at increased risk for mental health problems. Thus, despite effective mitigation of the pandemic, there was a striking deterioration of mental health. As the psychological burden of the continuing pandemic accrues, the probability of an impending mental health crisis is increasing, especially in countries with greater infection and death rates than South Korea. Comprehensive efforts to address the psychological aftermath of the pandemic are urgently needed.