For half a century, immunization has served as one of the most powerful tools in the global medical arsenal, fundamentally altering the trajectory of child survival. In the South-East Asia region, the impact has been profound, contributing to a significant reduction in preventable deaths and a 22% decline in infant mortality according to the World Health Organization (WHO) South-East Asia. Yet, beneath these aggregate successes lies a precarious gap in equity that threatens to undermine decades of hard-won progress.
The World Health Organization has issued a critical call for sustained efforts to expand vaccine access, warning that millions of people remain unprotected. While the region has evolved into a global vaccine production powerhouse—supplying nearly half of the world’s vaccines—the “last mile” of delivery remains a significant hurdle. The disparity in coverage is not merely a logistical failure but a public health risk, as uneven immunization levels create pockets of vulnerability that can trigger sudden, widespread outbreaks.
At the heart of this crisis are the “zero-dose” children—infants and toddlers who have not received a single dose of any vaccine. These children are often the most marginalized, living in informal urban settlements, remote border regions, or underserved rural areas. For these populations, the barriers are multifaceted, ranging from the physical distance to health clinics and the prohibitive cost of transport to a lack of official documentation required to access government services.
The Crisis of the “Zero-Dose” Child
In the South-East Asia region, approximately 1.9 million children are currently classified as “zero-dose” per WHO regional data. This figure is a critical metric for health system performance; a zero-dose child is often a proxy for a total lack of contact with any primary healthcare services. When a child misses their first dose, they are significantly more likely to miss subsequent boosters, leaving them entirely susceptible to diseases that the world has the means to prevent.
The global landscape reflects a similar struggle. In 2024, more than 14 million infants worldwide received no vaccines, while nearly 20 million missed at least one essential dose. These gaps are rarely the result of vaccine shortages—especially in a region that produces so much of the global supply—but are instead driven by systemic inequities. Vulnerable groups, including migrant populations and those in conflict-affected areas, are disproportionately affected.
To address this, the WHO emphasizes the need for data-driven strategies. This involves moving beyond national averages to identify specific “missed communities” through granular mapping and tailoring services to the unique needs of those populations. Strengthening last-mile delivery systems—the final stage of the supply chain that brings the vaccine from a regional hub to a remote village—is essential to ensuring that geography does not determine a child’s right to health.
Historical Triumphs and Modern Vulnerabilities
The urgency of the current situation is underscored by how much has been achieved since the 1970s. During the early years of the Expanded Program on Immunization (EPI), only about 5% of children in the region received three doses of a DTP-containing vaccine (diphtheria, tetanus, and pertussis). Today, that figure has climbed to more than 94% according to WHO records. This massive scale-up has saved an estimated 38 million lives within the region alone, contributing to a global total of over 154 million lives saved by vaccines over the last 50 years.
The scope of immunization has also broadened significantly. Programs that once covered only six primary diseases have expanded to include 13 different antigens. This evolution has allowed the region to achieve landmark milestones, including the elimination of maternal and neonatal tetanus and the maintenance of a polio-free status since 2014 as verified by the WHO. The introduction of newer vaccines—such as those for human papillomavirus (HPV), pneumococcal conjugate, rotavirus, and inactivated poliovirus—has added layers of protection against cancer and severe pneumonia.
However, these gains are not permanent. The risk of “immunity gaps” is a constant threat. When immunization coverage falters, the resulting lack of herd immunity allows dormant pathogens to resurface. This is particularly evident with measles, a highly contagious virus that acts as a “canary in the coal mine” for failing immunization systems.
Case Study: The Measles Response in Bangladesh
The current volatility of immunization coverage is clearly illustrated by the situation in Bangladesh. To combat the risk of outbreaks, the Bangladeshi government, with the support of international partners, is currently executing a massive nationwide measles and rubella campaign. This initiative targets 18.03 million children between the ages of six months and five years per WHO reporting.
A critical component of this effort is the focus on high-risk zones, such as Cox’s Bazar, where more than 182,000 children are being targeted. Cox’s Bazar represents the exact type of “underserved area” the WHO warns about—a region with high population density, significant migrant movement, and strained infrastructure. By prioritizing these hotspots, health officials hope to plug the gaps that allow measles to spread rapidly through unvaccinated clusters.
Beyond Childhood: The Future of Life-Course Immunization
As the region faces emerging pressures from climate change, rapid urbanization, and migration, the role of vaccines is shifting. Immunization is no longer viewed solely as a pediatric intervention but as a foundation for resilient health systems across all age groups. This “life-course” approach suggests that vaccination should extend into adolescence, adulthood, and old age to address evolving health needs and the shifting epidemiology of infectious diseases.
expanded immunization plays a pivotal role in the global fight against antimicrobial resistance (AMR). By preventing infections from occurring in the first place, vaccines reduce the overall need for antibiotics, thereby slowing the development of drug-resistant “superbugs.” In an era where AMR is becoming a leading cause of death globally, vaccines are a primary line of defense.
Catharina Boehme, Officer-in-Charge at WHO South-East Asia, has emphasized that equity must remain the central pillar of these efforts. Reaching the most underserved populations is not just a moral imperative but a key measure of a health system’s overall performance. Central to this is the role of community health workers, who serve as the most trusted sources of information and are essential for maintaining public confidence in the face of vaccine hesitancy.
Key Takeaways for Public Health Resilience
- The Zero-Dose Gap: Approximately 1.9 million children in South-East Asia have received no vaccines, signaling a total disconnect from primary healthcare.
- Proven Impact: Vaccines have saved 38 million lives in the region over 50 years and reduced infant mortality by 22%.
- Systemic Barriers: Access is hindered by distance, cost, and lack of documentation in informal settlements and border regions.
- Strategic Shift: The focus is moving toward “life-course immunization,” targeting adolescents and adults alongside children.
- AMR Mitigation: Higher vaccine coverage directly reduces the reliance on antibiotics, helping to combat antimicrobial resistance.
The path toward universal vaccine access is achievable, but it requires a transition from broad national strategies to targeted, community-led interventions. As the South-East Asia region continues to leverage its position as a global production hub, the challenge remains ensuring that the vaccines manufactured within its borders actually reach the arms of the children who need them most.
The next critical checkpoint for the region will be the evaluation of the current measles and rubella campaigns across member states, with updated coverage data expected in the coming reporting cycle from the WHO South-East Asia regional office.
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