Introduction: The unprecedented COVID-19 pandemic has exposed healthcare professionals to exceptional situations that can lead to increased anxiety (i.e., infection anxiety, perceived vulnerability), traumatic stress and depression. We will investigate the development of these psychological disturbances in healthcare professionals at the treatment front line and second line during the COVID-19 pandemic over a 12-month period in different countries. Additionally, we will explore whether personal resilience factors and a work-related sense of coherence influence the development of mental health problems of healthcare professionals.

Methods and analysis: We plan to carry out a sequential qualitative–quantitative mixed-methods-design study. The quantitative phase consists of a longitudinal online survey based on six validated questionnaires, to be completed at three points in time. A qualitative analysis will follow at the end of the pandemic, to comprise at least nine semi-structured interviews. The a-priori sample size for the survey will be a minimum of 160 participants, which we will extend to 400, to compensate for drop-out. Recruitment into the study will be through personal invitations and the ‘snowballing’ sampling technique. Hierarchical linear regression combined with qualitative data analysis will facilitate greater understanding of any associations between resilience and mental health issues in healthcare professionals during pandemics.

Ethics and dissemination: The study participants will provide their electronic informed consent. All recorded data will be stored on a secured research server at the study site, which will only be accessible to the investigators. The Bern Cantonal Ethics Committee has waived the need for ethical approval (Req-2020-00355; 1 April, 2020). There are no ethical, legal or security issues regarding the data collection, processing, storage and dissemination in this project.

Trial registration: ISRCTN13694948 (date of registration: 1 April, 2020)