Last month, the United Nations children’s agency UNICEF and the World Health Organization sounded a troubling distress call. Because of disruptions to planned immunization campaigns, 125 million children around the world are waiting for essential vaccinations against diseases such as measles; diphtheria, tetanus and whooping cough (DTP); and polio. It is the “largest sustained drop in childhood immunization in a generation”, the organizations say.

The COVID-19 pandemic and its effects are the main reason immunization campaigns have been disrupted. Lockdowns, interruptions to supply chains and the diversion of community health workers to focus on treating people with COVID-19 have all contributed. Ongoing civil and political conflicts around the world have also played a part.