India's eVIN put a SIM temperature logger in every vaccine fridge nationwide

India's Universal Immunization Programme moved vaccines through a long cold chain ending in tens of thousands of primary health centres, where a pharmacist like Preeti Madawali in Belagavi, Karnataka once managed storage by paper logbook and guesswork. Doses could sit in a warm fridge nobody knew was failing, or one centre could run out while a neighbouring PHC held surplus it would expire. Managers learned about both only after the fact.

eVIN, introduced from 2014 by the health ministry with UNDP support under Gavi-backed health system strengthening funding, attacked the blindness. It paired two cheap pieces of technology: SIM-enabled temperature loggers installed on existing cold-chain equipment, reporting storage conditions remotely; and a mobile, cloud-based app through which cold-chain handlers report vaccine stocks, consumption and movement. Cloud dashboards gave programme managers real-time, end-to-end visibility of stocks and flows nationwide.

The rollout went state by state until eVIN covered all 36 states and union territories. At the mid-2020 milestone the ministry counted 23,507 cold-chain points across 585 districts using the system, about 23,900 electronic temperature loggers installed, and 41,420 cold-chain handlers trained in digital record-keeping. By 2022 UNDP reported live monitoring across more than 29,000 cold-chain points, around 5.5 million stock-management transactions a month, and near-total adherence by handlers — most of them women, hundreds of thousands of whom were trained into smartphone-based work.

The payoff compounded. When COVID-19 arrived, India did not need to invent a vaccine logistics nervous system; eVIN's model of digitized cold-chain points and app-reported stock became, as UNDP puts it, instrumental in conceptualizing and scaling Co-WIN, the platform that carried the world's largest vaccination drive.

Instrument the existing cold chain instead of rebuilding it

The cold chain's weak link was information, not equipment: freezers existed everywhere, but nobody above the district knew their temperature or contents in time to act.

SIM loggers turned the existing fleet of ice-lined refrigerators into a sensor network for the cost of a SIM card per fridge, avoiding a capital rebuild.

Putting the reporting app in the hands of the last-mile handler — and training 41,000+ of them — made the data self-updating rather than dependent on inspection visits.

Real-time stock visibility let programme managers reallocate surplus between adjacent facilities, cutting both expiry waste and stockout-driven missed immunizations.

The state built it as shared infrastructure with UNDP/Gavi funding, so every later program (COVID vaccines included) could reuse the rails instead of starting over.

When a supply chain fails through blindness rather than bad assets, telemetry beats replacement: sensors on existing equipment plus a last-mile reporting app give national-system data quality.

eVIN reached all 36 states and UTs and kept running as the routine immunization supply chain's digital backbone, with monthly transaction volumes in the millions. UNDP credits it with directly shaping Co-WIN's design for the COVID-19 campaign. The handler training also left a capability footprint: a workforce of largely women cold-chain handlers now works on smartphones as the default, with reported adherence near 100%.