Largest catch-up initiative delivers over 100 million childhood vaccinations

The Big Catch-Up, launched during World Immunization Week 2023, has delivered over 100 million vaccine doses to an estimated 18.3 million children across 36 countries Around 12.3 million were “zero-dose children” who had not previously received any vaccines and 15 million who had never received a measles vaccine. The initiative concluded in March 2026 and is on track to meet its target of catching up 21 million children – but agencies warn that many infants still miss out on lifesaving vaccines through routine immunization every year.The Big Catch-Up (BCU), a historic multi-year, multi-country effort to address vaccination declines driven largely by the COVID-19 pandemic, has reached an estimated 18.3 million children aged 1 to 5 across 36 countries with more than 100 million doses of life-saving vaccines, helping to narrow critical immunity gaps, announced Gavi, the Vaccine Alliance (Gavi), WHO, and UNICEF at the start of World Immunization Week.Of the 18.3 million children reached between 2023 and 2025, an estimated 12.3 million were “zero-dose children” who had not yet received a vaccine and 15 million had never received a measles vaccine. BCU also provided 23 million doses of inactivated polio vaccine (IPV) to un- and under-vaccinated children, an essential intervention to reach polio eradication. Programme implementation concluded on 31 March 2026. Although final data is still being compiled, the global initiative is forecasted to be on track to meet its target of reaching at least 21 million un- and under-immunized children.However, agencies warn that while catch-up vaccination is an important strategy for closing immunisation gaps, expanding the reach of routine immunization programmes remains the most effective and sustainable way to protect children and prevent outbreaks of vaccine-preventable diseases.Addressing the vaccine equity gapBeyond pandemic recovery, the BCU initiative focused on closing the vaccine equity gap. Million