NHS CHECK started as a major study of the impact of the COVID-19 pandemic on the short and long-term health and wellbeing of all staff working within 18 partner National Health Service (NHS) Trusts. All participants in the study are clinical staff, students, or support staff within the 18 NHS Trusts across England, United Kingdom. The participants were all aged over 18 years at recruitment, and were required to understand and communicate in English. The study is also partnered with the 'Tackling Inequalities and Discrimination Experiences in health Services (TIDES)' study to ensure representation of ethnic minorities, and to capture experiences of inequality and discrimination. Surveys were administered in Phase 1 (Baseline; April 2020-January 2021), Phase 2 (October 2020-July 2021), Phase 3 (April 2021-February 2022) and Phase 4 (February 2023-April 2023).