India has made significant progress on childhood immunization, but many children still miss vaccines or receive them later than recommended. Government-run immunization sessions provide vaccines free of charge, but caregivers may not always know which vaccine their child is due for or when it should be received.
Suvita’s two programs build on research in Haryana that tested approaches including community immunization ambassadors and targeted SMS reminders to increase childhood immunization uptake. Suvita has since adapted and implemented these approaches at scale in partnership with state governments in India.
Suvita has since enrolled around 6 million caregivers and 4 million pregnant women in its reminder programme and recruited around 15,000 immunization ambassadors. Messaging for both programmes runs through Telerivet, with caregiver reminders sent by SMS and ambassador communications sent through SMS and WhatsApp.
Reminders scheduled 18 months ahead
Suvita runs its own Python ETL pipelines and integrates with Telerivet through the REST API to manage messaging and scheduling workflows. Vaccination reminder schedules are generated based on each child’s vaccination timeline, and the full series is scheduled in one pass. For the caregiver SMS reminder programme, Suvita schedules approximately 20 messages per child, covering the vaccination schedule up to 18 months of age. Messages are timed around vaccine due dates and are personalized using message variables and embedded links.
At that scale, Suvita sends 3 to 4 million messages a month, with a large volume needing to be delivered within a narrow two-hour window between 5 pm and 7 pm. Telerivet can send across multiple routes at the same time, so each state has its own set of routes sized for its messaging volume.
"Once we've added the contacts and scheduled the messages, we can be confident that the messages will be sent." - Shweta Saxena, Suvita
Keeping the list clean
Contact data that comes from government sources can contain errors. Phone numbers may be incorrect, outdated, or may not belong to the intended caregiver.
Telerivet returns message delivery statuses and error codes through the API. Suvita analysed these codes to identify phone numbers that are permanently invalid or unreachable, and built an automated service that blocks those contacts from future sends. This prevents repeated attempts to send messages that are unlikely to be delivered, thus saving on messaging costs.
A second automated service handles opt-outs. It monitors inbound messages for stop keywords and automatically blocks contacts who ask to stop receiving messages.
Ambassadors, dashboards, and a chatbot
Suvita’s other programme identifies influencers in local communities and recruits them as immunization ambassadors to share vaccination information within their respective localities. Ambassadors receive an informational message every 10 days, alternating between WhatsApp and SMS. SMS messages are scheduled based on each ambassador’s joining date, and the sequence can continue for up to three years. In Bihar, the sequence includes around 33 messages, while in Maharashtra it includes around 20. The messages cover topics such as why particular vaccines matter, common side effects, and the diseases they help prevent. Telerivet makes it straightforward to schedule these long-running message sequences in advance.
A daily automated job pulls sent-message data, new contacts, and delivery statistics from Telerivet into Suvita’s own database. This data feeds dashboards that the team uses to monitor messaging performance and programme operations.
Suvita also runs a simple WhatsApp chatbot through Telerivet that generates a personalized vaccination schedule. When a user provides a child’s name and date of birth, Telerivet calls a REST API hosted on Suvita’s AWS infrastructure. Suvita’s API calculates the vaccination schedule and returns it to Telerivet, which then sends the response back to the user.
From 6 districts to 36
As Suvita expanded the reminder programme in Maharashtra, scheduling messages up to 18 months in advance for millions of contacts created a very large volume of future messages in storage.
Suvita raised the issue with Telerivet, and the Telerivet team made a significant change to how far-future scheduled messages were stored. Instead of keeping the entire 18-month schedule in active storage, only messages due within the next 10 days were retained there. This substantially reduced storage requirements and costs for Suvita, even though it also meant lower revenue for Telerivet.
The change removed an important technical constraint and was one of the factors that supported Suvita’s expansion in Maharashtra from 6 districts to all 36 districts.
Why Suvita stayed
Two years ago, while working out how to run WhatsApp at scale, Suvita looked seriously at moving that part of the program elsewhere but decided to stay due to the support provided by Telerivet.
"We've never got stuck with Telerivet. Anytime we have an issue, Telerivet’s team helps us understand the problem and works with us to find an alternative way to solve it.
I recommend Telerivet to anyone who asks me how we manage bulk messaging."
Program facts
Suvita's programs
- Organization: Suvita. Operates in India as a project of Development Consortium; Suvita UK is a registered charity (no. 1198512).
- Programs: SMS vaccination reminders for caregivers; immunization ambassador network.
- Program scale: 6 million caregivers enrolled, 4 million pregnant women enrolled, 15,000 ambassadors. Cumulative program totals, published by Suvita.
- Evidence base: Suvita’s programmes build on J-PAL randomized controlled trials conducted in Haryana, India, which tested approaches including community immunization ambassadors and targeted SMS reminders to increase childhood immunization uptake. The trials were separate from Suvita’s operations.
What runs on Telerivet
- Volume: At peak scale: 3 to 4 million messages per month.
- Channels: SMS, WhatsApp, missed calls.
- Schedule depth: ~20 caregiver SMS reminders up to 18 months; ambassador messaging for up to 3 years (33 messages in Bihar, 20 in Maharashtra).
- Features in use: REST API, contact import, scheduled messages, message variables, parallel routes, delivery error codes, inbound keyword services, opt-out handling, outbound calls to a customer-hosted API.
- Integration: Python ETL pipelines in both directions, custom dashboards built on exported Telerivet program data.
