A global vaccination effort launched in the aftermath of the COVID-19 pandemic has reached 18.3 million children across 36 countries, helping to close critical immunisation gaps and revive routine health services disrupted during the crisis.
The initiative, known as the Big Catch-Up, delivered over 100 million doses of life-saving vaccines between 2023 and 2025, targeting children aged one to five who had missed routine immunisations. The programme was spearheaded by major global health bodies, including World Health Organization, UNICEF, and Gavi, the Vaccine Alliance.
Of the children reached, about 12.3 million had never received a single vaccine—commonly referred to as “zero-dose” children—while roughly 15 million had not been vaccinated against measles, one of the most contagious childhood diseases. The programme also administered 23 million doses of inactivated polio vaccine, contributing to ongoing global eradication efforts.
The campaign focused largely on countries in Africa and Asia, which together account for about 60 per cent of the world’s unvaccinated children. In places like Ethiopia and Nigeria, millions of previously unreached children were vaccinated, marking significant progress in addressing long-standing gaps in healthcare access.
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Beyond immediate vaccination, the initiative strengthened health systems by training workers, improving tracking systems, and expanding outreach to older children who had been missed in earlier programmes.
Despite these gains, global health leaders have warned against complacency. They stress that while catch-up campaigns are effective, long-term success depends on strengthening routine immunisation systems. Rising cases of measles and persistent gaps in vaccine coverage remain a concern, especially in conflict-affected and underserved regions.
As the world marks World Immunisation Week 2026, health agencies are urging governments and partners to sustain investment and ensure that no child is left behind, emphasising that vaccines remain one of the most effective tools for protecting public health.
