We conducted a qualitative study to explore the barriers and enablers of a COVID-19 cohort study conducted in South Sudan and Eastern Democratic Republic of the Congo, to inform future research on COVID-19 and infectious diseases in humanitarian settings. We used a case study design embedded within the original prospective cohort study. Findings suggest most of the challenges affecting the cohort study were not specific to COVID-19 research but have been a feature of previous infectious disease research carried out in complex emergencies. However, the pandemic has exacerbated certain problems. Facilitating factors were also identified. The global impact of COVID-19, its high public profile, and specific pandemic policies pose further operational challenges for research in already complex humanitarian settings. Future studies could plan mitigation measures that include flexibility in staffing and budgets, strategies to expand testing, and early partnerships with local organizations and health authorities.