This study reviews the literature concerning mental health impacts faced by health care workers (HCW) during the COVID-19 pandemic and similar infectious disease outbreaks. Among HCW studied, 9.6-51% reported symptoms of post-traumatic stress disorder (PTSD), and 20-75% reported psychiatric symptoms, with a particularly high prevalence of anxiety and depression. In addition to depression and anxiety, other serious stress responses were also reported among HCW during the COVID-19 pandemic. Severe symptoms were found in 2.2-14.5% of all participants. The severity of mental health symptoms was influenced by age, sex, occupation, specialization, type of activities performed, proximity to COVID-19 patients, direct involvement in the pandemic emergency response, preventive interventions, resilience, and social support. Qualitative studies showed that positive and negative emotions among front-line nurses coexisted during the outbreak of the epidemic. In the early stage, negative emotions were dominant and positive emotions appeared gradually. Personal coping styles and psychological growth played important roles in maintaining mental health among nurses. Ambiguous roles, transitions in operating mode, unfamiliar work content, and reversal of daily schedules were the most common vocational problems. Parents’ inability to comprehend, concern for family members, and long-term isolation were the most common causes of psychological stress. Regular screening for evaluating stress, depression and anxiety, and effective interventions for health care workers should be performed by multidisciplinary psychiatry teams.