IntroductionThe COVID-19 pandemic impacted the operationalisation of non-COVID-19 clinical trials globally, particularly site and participant recruitment and trial success/stoppage. Trials which anticipate recruitment challenges may embed methods such as the QuinteT Recruitment Intervention (QRI) to help identify and understand the sources of challenges. Such interventions can help shed light on pandemic-related challenges. This paper reports our experience of the impact of the COVID-19 pandemic on conducting clinical trials with an embedded QRI, highlighting how the QRI aided in identifying challenges and potential solutions, particularly related to the site set-up and participant recruitment.Main bodyWe report on 13 UK clinical trials which included a QRI. Information is from QRI data and researchers’ experience and reflections. In most trials, recruitment was lower than even the lowest anticipated rates. The flexibility of the QRI facilitated rapid data collection to understand and document, and in some instances respond to, operational challenges. Challenges were mostly logistical, pandemic-related and beyond the control of the site or central trial teams. Specifically: disrupted and variable site opening timelines —often due to local research and development (R&D) delays— shortages of staff to recruit patients; fewer eligible patients or limited access to patients; and intervention-related factors. Almost all trials were affected by pandemic-related staffing issues including redeployment, prioritisation of COVID-19 care and research, and COVID-19-related staff illness and absence. Trials of elective procedures were particularly impacted by the pandemic, which caused changes to care/recruitment pathways, deprioritisation of services, reduced clinical and surgical capacity and longer waiting lists. Attempted solutions included extra engagement with staff and R&D departments, trial protocol changes (primarily moving online) and seeking additional resourcing.ConclusionWe have highlighted wide-ranging, extensive and consistent pandemic-related challenges faced by UK clinical trials, which the QRI helped to identify and, in some cases, address. Many challenges were insurmountable at individual trials or trials unit level. This overview highlights the need to streamline trial regulatory processes, address staffing crises, improve recognition of NHS research staff and for clearer, more nuanced central guidance on the prioritisation of studies and how to deal with the backlog. Pre-emptively embedding qualitative work and stakeholder consultation into trials with anticipated difficulties, moving some processes online, and flexible trial protocols may improve the resilience of trials in the current challenging context.