Summary

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.

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