Measles outbreaks continue to pose a public health concern across South-East Asia despite the region achieving its highest-ever childhood immunisation coverage, the World Health Organization (WHO) has said.
The concern was highlighted at the 17th meeting of the WHO South-East Asia Regional Immunisation Technical Advisory Group (SEAR ITAG), being held in New Delhi. The three-day meeting brings together immunisation experts, health officials and representatives of national advisory groups to review vaccination programmes and disease-control efforts across the region.
The WHO said the region recorded 94% coverage for the third dose of the diphtheria, tetanus and pertussis (DTP3) vaccine in 2025, the highest level globally. The number of children receiving no routine vaccines has also fallen significantly.
The estimated number of zero-dose children dropped by 65% between 2021 and 2025, while the number of unvaccinated and under-vaccinated children fell from about 4.5 million in 2019 to 2 million in 2025.
However, regional averages can conceal significant gaps between communities. Some children, particularly those living in hard-to-reach or underserved areas, may still miss routine vaccinations or fail to receive all recommended doses.
Measles remains a concern
Measles is one of the biggest challenges facing immunisation programmes in the region. The disease is highly contagious and can spread rapidly when immunity levels fall within communities.
The WHO South-East Asia Region has not yet reached its measles elimination target. Only four of the region’s 10 member states have achieved measles elimination, while seven have achieved rubella elimination.
Recent measles activity in several countries has highlighted the continuing vulnerability of communities with immunity gaps. Bangladesh, India, Nepal, Thailand and the Maldives have reported measles outbreaks or increased transmission, according to WHO assessments.
Health experts say identifying children who have missed vaccines is particularly important because national vaccination coverage alone may not show where these gaps exist.
The WHO has called for greater use of subnational immunisation data to identify communities with lower vaccination coverage. Such information can help health authorities direct vaccination drives and other public health measures towards areas at higher risk.
Older children also need attention
While childhood vaccination remains central to disease prevention, experts are increasingly concerned about immunity gaps among older children and adolescents.
Children who missed routine vaccinations during earlier years may remain vulnerable later in life. Population movement, disruptions to healthcare services and difficulties accessing health facilities can contribute to these gaps.
The WHO meeting is therefore reviewing ways to strengthen routine immunisation as well as catch-up vaccination programmes.
Health authorities are also assessing the quality of measles and rubella surveillance. Early detection of suspected cases, laboratory confirmation and rapid outbreak investigation can help prevent isolated cases from developing into wider outbreaks.
HPV vaccination remains low
Adolescent vaccination is another area where South-East Asia faces challenges.
The WHO said HPV vaccination coverage was only 7% in the region in 2025, significantly below the regional target of 48% for 2026.
Human papillomavirus, or HPV, is associated with cervical cancer and several other cancers. Increasing HPV vaccination among adolescents is therefore an important part of long-term cancer prevention.
The WHO and regional health authorities are also examining the use of vaccines that remain under-utilised in some countries, including vaccines against typhoid, pneumococcal disease and rotavirus.
Expanding access to these vaccines could help reduce illness among children and strengthen protection against vaccine-preventable diseases.
Financing and misinformation add pressure
Vaccination programmes face challenges beyond vaccine supply. The WHO meeting is also examining immunisation financing, healthcare workforce capacity, vaccine information systems, laboratory services and vaccine confidence.
Misinformation about vaccines remains an additional challenge. Public health experts stress the need for clear and credible communication so that parents and communities understand the benefits of vaccination and have access to reliable information.
Maintaining public trust becomes especially important during outbreaks, when rumours and misinformation can spread quickly alongside the disease itself.
Climate and migration create new challenges
The WHO is also considering how wider changes could affect vaccination programmes.
Climate change, urbanisation, migration and humanitarian emergencies can disrupt routine healthcare services and make it harder to reach vulnerable populations. Migrant and mobile communities may also be missed by conventional vaccination systems.
Stronger immunisation records and disease surveillance can help health authorities track vaccination gaps and respond more quickly when outbreaks occur.
The WHO meeting will contribute to priorities for the region’s next Regional Vaccine Implementation Plan beyond 2026. Accelerating measles and rubella elimination, improving vaccination coverage, strengthening disease surveillance and securing sustainable immunisation financing are among the key areas under discussion.
The situation highlights an important public health lesson: high vaccination coverage at the national or regional level does not necessarily mean every child is protected.
For measles elimination to become sustainable, health systems need to identify missed children, close local immunity gaps and respond quickly when cases appear. Targeted vaccination, reliable surveillance and continued public confidence in immunisation will remain critical to preventing future outbreaks across South-East Asia.
