Global Vaccination Coverage and Public Health Impact

Abstract

Vaccination is arguably the most cost-effective public health intervention ever developed, preventing an estimated 154 million deaths over the past 50 years and contributing more to global life expectancy gains than any other single medical advance. Yet global vaccination coverage stalled and then declined during the COVID-19 pandemic, with DTP3 coverage falling from 86% in 2019 to 81% in 2021 -- the largest sustained decline in three decades -- leaving 25 million children under-vaccinated or zero-dose. Meanwhile, COVID-19 vaccination achieved unprecedented speed but profoundly inequitable distribution, with high-income countries reaching 75% coverage while low-income countries remained below 25%. We analysed vaccination coverage trends, programme effectiveness, and public health impact across 142 countries from 2000 to 2022 using WHO/UNICEF Estimates of National Immunization Coverage (WUENIC), Gavi programme data, COVID-19 vaccination records, and disease burden estimates from the Global Burden of Disease Study. We compared five vaccination programme frameworks: traditional Expanded Programme on Immunization (EPI), Gavi-supported accelerated introduction, catch-up and supplementary immunisation activities, digital registry-enabled tracking, and COVID-19 rapid deployment platforms. Our Vaccination Programme Effectiveness Score (VPES) integrates coverage achievement, equity across wealth quintiles, disease burden reduction, programme sustainability, and community trust. Digital registry-enabled tracking achieved the highest VPES (0.928) by reducing zero-dose children by 42% through individual-level identification and targeted outreach, while Gavi-accelerated introduction (VPES 0.912) demonstrated the fastest new vaccine adoption.