OBJECTIVES: To determine the volume of health professionals who suffered distress due to their care of patients with COVID-19 and to analyse the direction in which the response capacity of the professionals to face future waves of COVID-19 is evolving. DESIGN: A cross-sectional study. SETTING: Primary care and hospitals in Spain. PARTICIPANTS: A non-randomised sample of 685 professionals (physicians, nurses and other health staff). PRIMARY AND SECONDARY OUTCOME MEASURES: Frequency and intensity of stress responses measured by the Acute Stress of Health Professionals Caring COVID-19 Scale (EASE). Variation of stress responses according to the number of deaths per day per territory and the evolutionary stage of the COVID-19 outbreak measured by the Kruskal-Wallis and the Mann-Whitney U tests. RESULTS: The average score on the EASE Scale was 11.1 (SD 6.7) out of 30. Among the participants, 44.2% presented a good emotional adjustment, 27.4% a tolerable level of distress, 23.9% medium-high emotional load and 4.5% extreme acute stress. The stress responses were more intense in the most affected territories (12.1 vs 9.3, p=0.003) and during the disillusionment phase (12.7 vs 8.5 impact, 10.2 heroic and 9.8 honeymoon, p=0.000). CONCLUSIONS: The pandemic has affected the mental health of a significant proportion of health professionals which may reduce their resilience in the face of future waves of COVID-19. The institutional approaches to support the psychological needs of health professionals are essential to ensure optimal care considering these results.