From Invisible to Immunized: How TrackVac Is finding India’s most missed children

Across 143 Gavi-supported districts in 11 states of India, thousands of children remain unseen by the immunization system each year. These are "zero-dose" children-those who have not received even a first dose of the pentavalent vaccine before their first birthday-or children who were identified once but subsequently missed. While monitoring mechanisms existed, the absence of a standardized follow-up system meant that identification did not consistently translate into vaccination. For many children, being missed once meant remaining missed.

Turning identification into action

To address this critical gap, WHO India developed TrackVac, a digital portal designed to convert fragmented monitoring information into a standardized, actionable line list of every unvaccinated child-down to the sub-centre level. TrackVac bridges the divide between data collection and service delivery by ensuring that every identified child is systematically followed up for vaccination.

Each week, field monitors, external monitors, rapid response teams (RRTs), Focal Persons for Immunization in Urban Cities (FPI-UCs), and Surveillance Medical Officers (SMOs) work alongside Auxiliary Nurse Midwives (ANMs) to physically verify children's vaccination status. This process includes antigen-wise recording of outcomes, cross-checking written health-worker registers, and establishing linkages with the U-WIN platform to enable real-time digital tracking of vaccination records.

For children missing from all records, TrackVac allows immediate on-the-spot digital entry-often the first formal acknowledgement of the child within the public health system. Verified line lists are then shared directly with frontline health workers and district officials, enabling prompt, targeted follow-up.

Structured insights from the last mile

TrackVac goes beyond listing missed children. The platform captures structured information on the reasons for non-vaccination through standardized dropdown options, including refusal, migration, or fear of adverse events following immunization (AEFI). This transforms field observations into actionable intelligence, helping programme managers understand not only who is missed, but why.

Results that strengthen the system

In 2025 alone, TrackVac validated 224,698 children across 11 states. Among them, 53% were successfully vaccinated, and 58% received their due doses within 60 days of identification. Importantly, 33% of identified zero-dose children received their first DPT dose, marking a critical step toward full immunization.

The initiative also strengthened system visibility: 85% of validated children were found in existing health-worker records, reinforcing the accuracy and completeness of routine data systems. At the same time, TrackVac revealed persistent demand-side challenges-39% of children remained unvaccinated due to caregiver refusal, while 34% were missed because families had migrated. These findings underscore that closing immunization gaps requires both strong service delivery and sustained community engagement.

TrackVac digital validation by WHO rapid response team personnel at Bolsong Subcenter, North Garo Hills, Meghalaya
Photo Credit: WHO/India/Abel Marak

A scalable model for zero-dose elimination

TrackVac demonstrates a fundamental lesson for immunization programmes: identifying missed children is not enough. Systems must be designed to convert identification into timely action. By providing verified child-specific lists and a structured validation protocol, TrackVac equips frontline workers with practical tools to reach unreached children.

As India advances toward zero-dose reduction and universal immunization goals, TrackVac offers a scalable, evidence-based model for last-mile action. For every generation, vaccines must not only exist-they must reach every child.