Introduction: Two billion people are currently affected by complex humanitarian emergencies (CHEs) resulting from natural disasters and armed confl ict. Many have been displaced into crowded camps with poor access to water, sanitation, and health care. Humanitarian response is challenging under these circumstances, raising concern about the impact of COVID-19 on crisis-aff ected populations. Methods: This article examines CHEs in the Democratic Republic of Congo, Bangladesh, and Yemen, where protracted crises have displaced millions of people.