WHO Global Alliance Delivers 100 Million Childhood Vaccine Doses Since 2023 in Historic Catch-Up Drive
Published on Reflecto News | World News | Public Health
More than 100 million vaccine doses have been delivered to an estimated 18.3 million children worldwide since 2023 under a global initiative to reverse pandemic-related declines in childhood immunization, the World Health Organization (WHO) and vaccine alliance Gavi announced on Thursday .
The program, known as “The Big Catch-Up” (BCU), was launched during World Immunization Week in 2023 and concluded in March 2026. The initiative targeted children aged 1 to 5 years across 36 countries, focusing on those who missed routine vaccinations during the COVID-19 pandemic .
Key Milestones of the Initiative
| Metric | Figure |
|---|---|
| Total children reached | 18.3 million |
| Total vaccine doses delivered | 100 million+ |
| “Zero-dose” children vaccinated | 12.3 million |
| Children who received first measles vaccine | 15 million |
| Polio vaccine doses administered | 23 million |
| Countries participating | 36 |
*Source: WHO/Gavi/UNICEF joint statement *
Of the 18.3 million children reached between 2023 and 2025, approximately 12.3 million were “zero-dose children” who had never received any vaccine before the campaign, while 15 million had never received a measles vaccine . The initiative also provided 23 million doses of inactivated polio vaccine (IPV), an essential intervention toward polio eradication .
Reaching the Most Vulnerable
The 36 participating countries across Africa and Asia account for 60% of all zero-dose children worldwide . The initiative specifically focused on closing the vaccine equity gap, reaching children living in fragile, conflict-affected, or underserved communities who are typically missed by routine immunization services .
Top-performing countries included:
- Ethiopia: Over 2.5 million previously zero-dose children received their first dose of diphtheria-tetanus-pertussis (DTP1) vaccine; also delivered nearly 5 million IPV doses and over 4 million measles vaccine doses
- Nigeria: 2 million previously zero-dose children reached with DTP1; 3.4 million IPV doses administered
Twelve countries reported reaching more than 60% of all zero-dose children under age 5 who had previously missed DTP1 vaccination: Burkina Faso, Democratic People’s Republic of Korea, Ethiopia, Kenya, Madagascar, Mauritania, Niger, Pakistan, Somalia, Togo, United Republic of Tanzania, and Zambia .
A Historic First: Reaching Older Children
For the first time ever, countries and global partners systematically leveraged routine immunization systems to reach the accumulated global cohort of “older” children between ages 1 and 5 — children who should have received critical routine vaccines before age 1 but remained vulnerable due to missed vaccinations .
The BCU catalyzed long-lasting systems to identify, screen, vaccinate and monitor coverage rates in these older children, including updates to policies on age eligibility. Countries also oriented and trained health workers to identify and vaccinate missed children as part of routine care .
Statements from Global Health Leaders
Dr. Sania Nishtar, CEO of Gavi, the Vaccine Alliance: “As the largest ever international effort to reach missed children with life-saving vaccines, the Big Catch-Up shows what is possible when governments, partners and communities work together to protect the most vulnerable in society. Thanks to this accomplishment, not only are millions of children now protected from preventable diseases but so are their communities, for generations to come.”
Dr. Tedros Adhanom Ghebreyesus, WHO Director-General: “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 success of the Big Catch-Up is a testament to health workers and national immunization programmes, which are now better equipped to find and vaccinate children missed by routine services.”
Catherine Russell, UNICEF Executive Director: “Vaccinations save lives. This initiative shows what’s possible when countries have the resources, tools, and political will to reach children with lifesaving vaccines. We’ve caught up with some of the children who missed routine vaccinations during the pandemic — but many more remain out of reach.”
Challenges Ahead: Funding Cuts and Persistent Gaps
Despite the success of the catch-up drive, global health leaders warn that significant challenges remain. The push comes at a time when some traditional backers such as the United States are scaling back aid .
Ephrem Lemango, Chief of Immunization at UNICEF, said recent sharp funding cuts to global health have “seriously affected delivery of immunization services” and could “likely reverse hard earned progress” .
In 2024, an estimated 14.3 million infants under age 1 globally failed to receive a single vaccine through routine immunization programs. Countries in the midst of global conflict saw some of the sharpest setbacks .
Measles Resurgence Warning
The consequences of chronic gaps in routine immunization are already visible. Measles outbreaks are rising in every region, with approximately 11 million cases in 2024. The number of countries facing large outbreaks has nearly tripled since 2021 .
Agencies warn that while catch-up vaccination is an important strategy for closing immunization gaps, expanding the reach of routine immunization programs remains the most effective and sustainable way to protect children and prevent outbreaks of vaccine-preventable diseases .
Looking Forward: For Every Generation, Vaccines Work
The BCU initiative was forecasted to be on track to meet its target of reaching at least 21 million un- and under-immunized children, though final data is still being compiled .
WHO, UNICEF, and Gavi are marking World Immunization Week (24-30 April 2026) with a joint campaign, “For every generation, vaccines work,” calling on countries to sustain and expand vaccination coverage at every age .
At the midpoint of the Immunization Agenda 2030 (IA2030), and central to Gavi’s 2026-2030 strategy (Gavi 6.0), the priority remains the same: reaching zero-dose children and advancing equity in the hardest-to-reach communities, particularly in countries grappling with conflict, instability, or fragile health systems .
Frequently Asked Questions (FAQs)
1. What is “The Big Catch-Up”?
The Big Catch-Up (BCU) is a historic multi-year, multi-country initiative launched in 2023 to address vaccination declines caused by the COVID-19 pandemic. It concluded in March 2026 and focused on reaching children aged 1 to 5 who missed routine vaccinations .
2. How many children were reached by the initiative?
The initiative reached an estimated 18.3 million children across 36 countries, delivering more than 100 million vaccine doses .
3. Which organizations led the campaign?
The campaign was led by Gavi, the Vaccine Alliance, the World Health Organization (WHO), and UNICEF .
4. What is a “zero-dose” child?
A “zero-dose” child is one who has never received any vaccine. The BCU reached approximately 12.3 million zero-dose children .
5. Why is routine immunization still important?
While catch-up campaigns are effective for closing immediate gaps, expanding routine immunization programs remains the most sustainable way to protect children and prevent outbreaks of vaccine-preventable diseases .
6. Is the initiative complete?
Yes, program implementation concluded on March 31, 2026. Final data is still being compiled, but the initiative is forecasted to meet its target of reaching at least 21 million children .
7. What challenges remain?
An estimated 14.3 million infants under age 1 missed basic vaccinations in 2024. Funding cuts to global health programs, conflicts, displacement, and strained health systems continue to threaten progress .
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