New Delhi: The WHO South-East Asia Region, despite recording the world's highest childhood immunisation coverage, continues to face measles and other vaccine-preventable disease outbreaks due to persistent immunity gaps among children and adolescents, health experts said.
The issue was discussed at the 17th meeting of the WHO South-East Asia Regional Immunisation Technical Advisory Group (SEAR ITAG) in Delhi, attended by around 120 experts, Member State representatives and other stakeholders.
WHO South-East Asia Region Officer-in-Charge Dr Nilesh Buddha stressed the need to strengthen monitoring, surveillance and use of local data to identify and close immunity gaps.
"Progress must not become complacency. Sustaining high immunisation coverage requires strong monitoring, timely use of local data and rigorous programme review. We need to close the immunity gaps, strengthen surveillance and ensure that every child and every community is reached with life-saving vaccines," said Dr Nilesh Buddha, Officer-in-Charge, WHO South-East Asia Region, in his inaugural address to the 17th meeting of the WHO South-East Asia Regional Immunisation Technical Advisory Group (SEAR ITAG).
The SEAR ITAG Chair, Professor Rakesh Aggarwal, noted that immunisation coverage at the national level alone may not reflect gaps in subnational and hard-to-reach communities.
He emphasised the need for local data and epidemiological evidence to guide targeted immunisation efforts and ensure that vulnerable populations are reached.
According to WHO, the region recorded 94 per cent coverage with the third dose of the routine diphtheria, tetanus and pertussis (DTP3) vaccine in 2025, the highest globally.
The number of zero-dose children in the region has declined by 65 per cent since 2021, while the number of unvaccinated and under-vaccinated children fell from an estimated 4.5 million in 2019 to 2 million in 2025.
However, vaccination gaps persist both between and within countries, leaving pockets of susceptible populations and contributing to outbreaks.
Measles remains a particular concern, with immunity gaps among older children and adolescents driving current transmission and outbreaks, according to the WHO.
The region has also fallen behind its measles elimination trajectory, with only four of its 10 member states having achieved measles elimination. In comparison, seven member states have achieved rubella elimination.
Additionally, experts are reviewing progress under the Regional Vaccine Implementation Plan (RVIP) 2022-26, which focuses on equitable access to vaccines, control and elimination of vaccine-preventable diseases and reducing related morbidity and mortality across the life-course.
The meeting is also examining childhood and adolescent vaccination, including HPV immunisation.
HPV vaccination coverage in the region stood at 7 per cent in 2025, while the region has set a target of reaching 48 per cent coverage in 2026.
The advisory group is also reviewing the prioritisation and introduction of new and under-utilised vaccines, including typhoid conjugate, pneumococcal conjugate and rotavirus vaccines.
The three-day meeting, which began on Wednesday, is also discussing sustainable immunisation financing, workforce capacity, surveillance and laboratory systems, immunisation information systems, vaccine hesitancy and misinformation.
Experts will also examine the impact of climate change, urbanisation, migration and humanitarian emergencies on immunisation programmes.
The group is expected to guide priorities for the next regional vaccine implementation plan beyond 2026, including accelerating measles and rubella elimination, reducing outbreak risks, strengthening domestic financing and partnerships, and sustaining surveillance for vaccine-preventable diseases.