Background: The coronavirus disease 2019, or COVID-19, has had a major psychological impact on healthcare workers. However, very few scales are available to specifically assess work-related stress and anxiety in healthcare workers responding to a viral epidemic. This study developed a new assessment tool, the Stress and Anxiety to Viral Epidemics-9 (SAVE-9) and aimed to validate it among healthcare workers directly affected by COVID-19 in Korea. Methods: A total of 1,019 healthcare workers responded through anonymous questionnaires during April 20–30, 2020. Exploratory factor analysis (EFA) was conducted to explore the construct validity, and the reliability was assessed using internal consistency measures of Cronbach's alpha coefficients. Receiver operating characteristic analysis was conducted to define the most appropriate cut-off point of SAVE-9 using the Generalized Anxiety Disorder-7 scale (GAD-7; ≥ 5). Second, Spearman's rank correlation coefficient was used to establish convergent validity for the SAVE-9 questionnaire with GAD-7 and the Patient Health Questionnaire-9. Results: The nine-item scale had satisfactory internal consistency (Cronbach's α = 0.795). It adopted a two-factor structure: 1) anxiety regarding viral epidemics and 2) work-related stress associated with viral epidemics. A cut-off score of 22 for the SAVE-9 ascertained levels of stress and anxiety in response to a viral epidemic in healthcare workers that warranted clinical attention. Correlations between the SAVE-9 and the other scales were statistically significant (P < 0.05). Conclusion The results suggest that the SAVE-9 is a useful, reliable, and valid tool to evaluate stress and anxiety responses in healthcare workers during viral epidemics.