This longitudinal study aimed to explore anxiety and depressive symptoms, individual resources, and job demands in a multi-country sample of 612 healthcare workers (HCWs) during the COVID-19 pandemic. Two online surveys were distributed to HCWs in seven countries (Germany, Andorra, Ireland, Spain, Italy, Romania, Iran) during the first (May-October 2020, T1) and the second (February-April 2021, T2) phase of the pandemic, assessing sociodemographic characteristics, contact with COVID-19 patients, anxiety and depressive symptoms, self-compassion, sense of coherence, social support, risk perception, and health and safety at the workplace. HCWs reported a significant increase in depressive and anxiety symptoms. HCWs with high depressive or anxiety symptoms at T1 and T2 reported a history of mental illness and lower self-compassion and sense of coherence over time. Risk perception, self-compassion, sense of coherence, and social support were strong independent predictors of depressive and anxiety symptoms at T2, even after controlling for baseline depressive or anxiety symptoms and sociodemographic variables. These findings pointed out that HCWs during the COVID-19 outbreak experienced a high burden of psychological distress. The mental health and resilience of HCWs should be supported during disease outbreaks by instituting workplace interventions for psychological support.