In the quiet margins of India’s immunization map, a familiar problem has long persisted: some children were identified but not reached. Across 143 Gavi-supported districts in 11 states, some “zero dose” children—those who have not received even a first vaccine—continued to slip between the cracks each year. Monitoring systems could find them, but the pathway to follow up was patchy, which increased their risk of being missed for good.
That pattern is beginning to change.
A digital platform called TrackVac, developed by WHO India, is turning scattered data into something far more powerful: a clear, actionable list of every unvaccinated child, right down to the health sub-centre level. Its premise is simple but transformative—every identified child must be followed, verified, and reached.
Each week, a network of field monitors, rapid response teams, and immunization focal points work alongside frontline health workers to do exactly that. They go door to door, checking records, confirming vaccination status antigen by antigen, and linking findings to real-time digital systems. When a child is missing from all records, TrackVac allows immediate entry on the spot—often marking that child’s first formal inclusion in the public health system.
What emerges is not just a list, but a live system of accountability. Verified data flows directly to those who can act on it: auxiliary nurse midwives and district officials who can plan targeted follow-ups without delay.
Crucially, TrackVac doesn’t stop at the ‘who’. It captures the ‘why’. Standardized insights—whether a family has migrated, refused vaccination, or fears side effects—turn field observations into programme intelligence. This clarity is helping shift responses from generic outreach to tailored engagement.
The results are tangible. In 2025, TrackVac validated over 224 000 children. More than half were vaccinated, many within two months of being identified. One in three zero-dose children received their first critical shot. At the same time, the system strengthened routine data itself, confirming that most children were already recorded—just not consistently followed up.
The remaining gaps tell their own story: mobility, mistrust, and missed opportunities. But they are now visible, measurable, and increasingly, addressable.
TrackVac’s success lies in a simple shift—from counting missed children to closing the gap. It demonstrates that the last mile of immunization is not just about access, but about systems that ensure no child is forgotten after being found.
Because vaccines only save lives when they reach the child.