Background Extreme events (e.g., floods, hurricanes) can overwhelm healthcare workers and systems. Similarly, healthcare workers were particularly affected during the COVID-19 pandemic, and high levels of distress and mental ill health have been reported. Aim To examine and synthesise qualitative research findings regarding the stressors, and their psychosocial impacts, that healthcare staff faced in the UK during the COVID-19 pandemic, and to provide lessons for future support. Method A systematic review, pre-registered on PROSPERO (CRD42022304235), was carried out on papers reporting qualitative research published between January 2021 and January 2022 that focused on the impact of COVID-19 on UK healthcare workers. Findings from 27 qualitative papers were integrated using thematic synthesis. Results Several types of stressors were identified including the SARS-CoV-2 virus, problems related to personal protective equipment, leadership, and communication processes, high workloads, and issues stemming from uncertainty and a lack of knowledge. These stressors were related to a range of adverse psychosocial outcomes including worrying about oneself and others, fatigue, lack of confidence in oneself and in senior managers, impacts on teamwork, and feeling unappreciated or that one's needs are not recognised. Conclusions Apart from COVID-19 itself (the primary stressor), healthcare staff experienced distress due to ineffective policies, practices and administrative arrangements that were in place before the pandemic, or from insufficient or ineffective responses to the pandemic (secondary stressors). However, secondary stressors can be modified to mitigate their negative effects, thus workforce planning should shift from focusing on individuals towards amending healthcare staff's psychosocial working environments.

AW is employed by the Institute for Clinical and Economic Review (ICER). AW completed this work independent of ICER. Collection of the 27 articles reported on in this paper was funded by NHS England. NHS England did not commission and had no input into designing the methodology of the systematic review reported in this paper. It made no contribution to the analyses or to interpretation of the findings. The information contained in the report represents the views of the research team and does not represent the views of NHS England or the authors' employing institutions.

Collection of the 27 articles reported on in this paper was funded by NHS England. NHS England did not commission and had no input into designing the methodology of the systematic review reported in this paper. It made no contribution to the analyses or to interpretation of the findings. The information contained in the report represents the views of the research team and does not represent the views of NHS England or the authors' employing institutions.

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This study is a systematic review of published papers - all the studies used in the review are listed in a table in the paper itself.