The World Health Organization (WHO) South-East Asia Region on Friday called for stronger and sustained efforts to ensure vaccines reach every community, warning that millions of people remain unvaccinated despite decades of progress in immunization.

WHO said vaccines have saved more than 154 million lives globally over the past 50 years, including an estimated 38 million in the South-East Asia Region. Immunization has also contributed to a 22 per cent decline in infant mortality across the region.

“Vaccines are one of the most powerful and cost-effective health investments we have,” said Dr Catharina Boehme, Officer-in-Charge, WHO South-East Asia Region. “Maximizing their impact depends on ensuring they reach everyone, everywhere.”

Globally, WHO said over 14 million infants received no vaccines in 2024, while nearly 20 million missed at least one essential dose. It said the figures underline the need to improve access and service delivery, particularly for vulnerable and underserved populations.

“Achieving and sustaining high immunization coverage remains critical, as any gaps can increase the risk of outbreaks. The ongoing measles situation in Bangladesh highlights this risk. The Government, supported by partners, is scaling up a nationwide measles and rubella vaccination campaign to reach 18.03 million children aged 6 months to 5 years, including 182 270 children in Cox’s Bazar. This underscores the importance of ensuring all children receive timely, life-saving vaccines, particularly in high-risk and vulnerable settings,” Dr Boehme said.

The WHO South-East Asia Region, home to nearly a quarter of the global population, has made major gains through sustained political commitment and investment. More than 94 per cent of children now receive three doses of DTP-containing vaccine, compared to only 5 per cent in the early years of the Expanded Programme on Immunization.

Since the 1970s, immunization programmes in the region have expanded from protection against six diseases to 13 antigens. WHO said these efforts helped eliminate maternal and neonatal tetanus, sustain polio-free status since 2014, and advance progress toward measles and rubella elimination. Several countries have also introduced newer vaccines, including Inactivated Poliovirus Vaccine, Human Papillomavirus vaccine, Pneumococcal Conjugate Vaccine and rotavirus vaccine.

The region has also become a major global vaccine manufacturing hub, producing nearly half of the world’s vaccine supply.

However, WHO said around 1.9 million children in the region remain “zero-dose”, meaning they have not received even a single vaccine. Many of them live in remote areas, urban informal settlements, border regions and migrant communities, facing barriers such as distance, cost and lack of access to services.

WHO stressed the need for targeted, data-driven strategies, stronger last-mile delivery systems and people-centred services to reach such populations.

“Equity remains central to immunization efforts,” said Dr Boehme. “Reaching those who are currently underserved is an important measure of health system performance.”

She also emphasized the importance of trust and community engagement, noting that health workers remain the most trusted source of vaccine information.

“Vaccines save lives,” said Dr Boehme. “Ensuring they reach everyone is both achievable and essential for stronger, more resilient societies.”

World Immunization Week is observed from April 24 to 30 each year to promote the use of vaccines for people of all ages. The 2026 theme is “For Every Generation, Vaccines Work.”