General information only. This Parent Resource summarizes WHO–UNICEF programme information and does not provide an individual vaccination schedule.
What was the Big Catch-Up?
WHO and UNICEF describe the Big Catch-Up as a multi-country effort launched after pandemic-related disruption to help reach children who had missed routine immunization.
How many children were reached?
The April 2026 joint release reports more than 100 million vaccine doses delivered to an estimated 18.3 million children across 36 countries.
What does “zero-dose” mean in this report?
The agencies use the term for children who had not previously received any routine vaccine; the initiative reached an estimated 12.3 million such children.
Did the programme replace routine immunization?
No. WHO and UNICEF state that catch-up vaccination helps close gaps while strong routine immunization remains the sustainable way to protect children over time.
References
- World Health Organization, UNICEF and partners. Largest catch-up initiative delivers over 100 million childhood vaccinations, 24 April 2026. Source reviewed 4 September 2026.