Trends in DTP3 Vaccination in Asia (2012-2023)

Abstract

BACKGROUND/OBJECTIVES: DTP3 (diphtheria-tetanus-pertussis vaccine, third dose) coverage is a key indicator of the strength and continuity of routine immunization programs, which demonstrably reduces the burden of infectious diseases globally. This study aims to assess trends in DTP3 vaccination coverage across Asian regions and countries from 2012 to 2023, focusing on changes associated with the COVID-19 pandemic. METHODS: DTP3 vaccination data were obtained from official WHO/UNICEF Estimates of National Immunization Coverage (WUENIC) and analyzed using Joinpoint regression to detect statistically significant changes in vaccination trends. Data were grouped by five Asian subregions based on the UN geoscheme (Central, Eastern, Southeastern, Southern, and Western Asia), and trends were weighted using birth cohort sizes. The presence of joinpoints and annual percentage changes (APCs) was calculated, and potential pandemic-related disruptions were contextualized. RESULTS: At the continental level, Asia experienced a modest 0.4% annual increase in DTP3 coverage between 2012 and 2023, with a significant joinpoint detected in 2018. Following this, Southeast Asia's coverage declined at an annual rate of -4.32% before beginning to recover in 2021, while South Asia showed a similar pattern. Country-level analysis revealed significant heterogeneity, with a comparison between 2019 and 2023 showing profound post-pandemic declines in some nations, such as Lebanon (-21%) and Myanmar (-9.4%), while others, like Iraq and the Philippines, achieved substantial recoveries with coverage increasing by over 6 percentage points. These trends contrasted with persistent declines in fragile states (e.g., Afghanistan, Yemen) and sustained high coverage in others (e.g., Bangladesh, Israel). The pandemic, systemic weaknesses, emerging vaccine hesitancy, and misinformation were identified as key influences. CONCLUSIONS: There is progress in DTP3 coverage across Asia. There were pandemic-related disruptions, particularly in regions with fragile health systems. Strategies to address zero-dose and dropout children, improve service continuity, and counter misinformation are essential to meet immunization targets under the Immunization Agenda 2030.