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Vaccines are one of the most cost-effective health tools ever invented. Yet 1 in 5 children still misses out on basic immunizations—this is unacceptable in the 21st century.

Margaret Chan

World Immunization Week message, 2017 · Checked on 3 March 2026
Vaccines are one of the most cost-effective health tools ever invented. Yet 1 in 5 children still misses out on basic immunizations—this is unacceptable in the 21st century.

Analysis

Vaccines are widely recognized as highly cost-effective by health economists, preventing 2-3 million deaths annually (WHO, 2023). At the time (2017), **19.5 million children** (≈1 in 5) missed basic vaccines like DTP3, per WHO/UNICEF estimates, aligning with Chan’s figure. The 'unacceptable' framing reflects global health equity goals but is a normative judgment rather than a factual claim. Post-2017 data shows slight improvements, but gaps persisted (e.g., 17.1 million unvaccinated in 2020).

Background

Margaret Chan served as WHO Director-General (2006–2017) and frequently advocated for immunization equity. **World Immunization Week** (last week of April) aims to highlight vaccine access disparities. The 1-in-5 statistic was a recurring WHO talking point during her tenure, citing stagnant coverage in conflict zones and low-income countries.

Verdict summary

Margaret Chan’s 2017 claim about vaccine cost-effectiveness and coverage gaps is accurate, supported by WHO data and independent research.

Sources consulted

— World Health Organization (2017). *Global Vaccine Action Plan 2011–2020: Mid-Term Review*. https://www.who.int/immunization/global_vaccine_action_plan/en/
— WHO/UNICEF (2017). *WHO Vaccine-Preventable Diseases: Monitoring System*. 2017 global summary. https://apps.who.int/immunization_monitoring/globalsummary/
— Ozgediz et al. (2018). *The economic value of vaccines: A systematic review*. *Vaccine*, 36(12), 1551–1567. https://doi.org/10.1016/j.vaccine.2018.01.055
— Gavi, the Vaccine Alliance (2023). *The Investment Case for Vaccines*. https://www.gavi.org/investing-gavi/value-vaccines
— WHO (2023). *Immunization Coverage*. Fact sheet. https://www.who.int/news-room/fact-sheets/detail/immunization-coverage