More than 12 million ‘zero-dose’ children reached as agencies intensify efforts to close immunisation gaps.
Geneva: The Big Catch-Up (BCU), a landmark multi-year and multi-country initiative launched to reverse vaccination declines largely caused by the COVID-19 pandemic, has reached an estimated 18.3 million children aged one to five across 36 countries.
More than 100 million doses of life-saving vaccines were delivered, helping to close critical immunity gaps, according to Gavi, the Vaccine Alliance, World Health Organization, 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 received a single vaccine, while 15 million had never been vaccinated against measles.
The Big Catch-Up also delivered 23 million doses of inactivated polio vaccine (IPV) to un- and under-vaccinated children, a critical step toward achieving polio eradication.
Programme implementation concluded on March 31, 2026. While final data is still being compiled, the global initiative is projected to remain on track to meet its goal of reaching at least 21 million un- and under-immunised children.
Health agencies caution that while catch-up vaccination campaigns are vital for closing immunisation gaps, strengthening routine immunisation programmes remains the most effective and sustainable way to protect children and prevent outbreaks of vaccine-preventable diseases.
Although the initiative concluded in March 2026 and is on track to meet its goal of reaching 21 million children, agencies warn that many infants still miss out on life-saving vaccines each year through routine immunisation services.
To mark World Immunization Week, World Health Organization, UNICEF, and Gavi, the Vaccine Alliance—together with countries and communities—have launched the joint campaign, “For every generation, vaccines work,” urging governments to sustain and expand vaccination coverage at every stage of life.
