Vaccine Catch-Up Reaches 18 Million Children Missed in the Pandemic

The COVID-19 pandemic disrupted routine immunization on a scale not seen in decades, leaving millions of children unprotected against diseases like measles, polio and diphtheria. On 24 April 2026, the World Health Organization announced that a major effort to reverse that damage — the Big Catch-Up initiative — had delivered more than 100 million vaccine doses to 18.3 million children aged one to five across 36 countries between 2023 and 2025.

Crucially, the campaign reached children who had slipped entirely through the cracks. An estimated 12.3 million of those reached were “zero-dose” children who had never received a single vaccine, and about 15 million had never received a measles vaccine. The initiative also delivered 23 million doses of inactivated polio vaccine. The 36 participating countries, spread across Africa and Asia, account for around 60% of the world’s zero-dose children, making them the right place to concentrate the push.

“On 24 April 2026, the World Health Organization announced that a major effort to reverse that damage — the Big Catch-Up initiative — had delivered more than 100 million vaccine doses to 18.”

The numbers behind individual countries show the scale of the work. Ethiopia reached 2.5 million zero-dose children with their first dose of diphtheria-tetanus-pertussis vaccine, and Nigeria reached 2 million. WHO Director-General Dr Tedros Adhanom Ghebreyesus said that “by protecting children who missed out on vaccinations because of disruptions to health services caused by COVID-19, the Big Catch-Up has helped to undo one of the pandemic’s major negative consequences.” The initiative is on track to meet its target of reaching 21 million un- and under-immunized children.

There is reason for both celebration and continued attention. Global coverage for the first measles dose still sits around 83%, well below the 95% needed to stop outbreaks, and sustaining catch-up gains depends on stable funding and strong routine systems. But reaching more than 18 million children — most of whom had never been vaccinated at all — is a powerful demonstration that, with coordinated effort, the world can repair even the deep setbacks left by the pandemic.