The largest sustained decline in childhood vaccinations in approximately 30 years has been recorded in official data published by WHO and UNICEF. The percentage of children who received three doses of the vaccine against diphtheria, tetanus and pertussis (DTP3) – a marker for immunization coverage within and across countries – fell 5 percentage points between 2019 and 2021 to 81 per cent. As a result, 25 million children missed out on one or more doses of DTP through routine immunization services in 2021 alone. This is 2 million more than those who missed out in 2020 and 6 million more than in 2019, highlighting the growing number of children at risk from devastating but preventable diseases. The decline was due to many factors including an increased number of children living in conflict and fragile settings where immunization access is often challenging, increased misinformation and COVID-19 related issues such as service and supply chain disruptions, resource diversion to response efforts, and containment measures that limited immunization service access and availability.