--- title: Sentinel Surveillance Application for Adverse Events of Special Interest (AESI) url: https://www.velsof.com/case-studies/sentinel-surveillance-application-for-adverse-events-of-special-interest-aesi/ date: 2026-02-15 type: case_study author: Velocity Software Solutions client: John Snow India Private Limited (JSIPL) industry: Public Health / COVID-19 Vaccine Safety / Surveillance location: "New Delhi, India (deployed across 16 sentinel sites in 13 states)" categories: Case Studies tags: COVID-19, Dashboard, Healthcare, Mobile App, Offline App, PHP development, Power BI, react-js-development, Web Application Development --- ## The Challenge Following the mass rollout of COVID-19 vaccines in India, the Ministry of Health and Family Welfare (MoHFW) identified a critical need to monitor Adverse Events of Special Interest (AESIs) — medical conditions potentially associated with vaccines manufactured on new or rarely used platforms. JSIPL, through its Immunization Technical Support Unit (ITSU), was commissioned to establish a sentinel surveillance system across 16 medical colleges distributed across 13 states to identify and capture AESIs in both vaccinated and unvaccinated individuals. Key challenges included: - **Limitations of Existing Tools**: The existing data collection system was built on a third-party open-source application with significant constraints — no “Save & Draft” option, frequent data loss, inability to download custom data, and storage space issues - **Complex Clinical Forms**: The surveillance required 11 interlinked forms (1 Case Screening Form and 10 Case Review Forms covering specific medical conditions), each with extensive clinical data elements - **Large File Sizes**: Each case file was estimated at 20-40 MB due to required image captures of hospital records, with each image optimized to 2-4 MB - **Remote Sentinel Sites**: The 16 sentinel sites were spread across 13 states (Andhra Pradesh, Assam, Delhi, Jharkhand, Karnataka, Madhya Pradesh, Maharashtra, Manipur, Odisha, Punjab, Rajasthan, Tamil Nadu, Uttarakhand) with varying connectivity levels - **Data Migration**: Existing surveillance data from the legacy system needed to be migrated to the new application without loss of historical records - **Strict User Role Management**: Different access levels required for Sentinel Site Officers (SSOs), Sentinel Site Associates (SSAs), Super Users, and Admin users ## Velocity’s Solution ### Scope of Work Velocity developed a complete replacement for the legacy surveillance system — a custom web-based and [Android](https://www.velsof.com/android-development/) application designed specifically for AESI sentinel surveillance. The application addressed all pain points of the existing system while introducing advanced capabilities for data capture, analysis, and reporting. ### Key Features & Deliverables - **Dual-Platform Application**: Web-based application for Windows and native Android app for tablet-based field data collection - **11 Interlinked Clinical Forms**: 1 Case Screening Form and 10 Case Review Forms with full interlinkage, enabling comprehensive AESI documentation   - **Save and Draft Functionality**: Robust save and draft capability solving the primary pain point of the legacy system, preventing data loss during complex form completion  - **Offline-First Architecture**: Complete offline data capture with automatic synchronization to the JSIPL server upon connectivity restoration - **Image Capture and Optimization**: In-app image capture and upload with optimization to 2-4 MB per image, coded and linked to unique case IDs for hospital record documentation - **Multi-Level [Dashboard](https://www.velsof.com/software-development/)**: Summary tables, KPIs, geographical case representation, and demographic visualizations (age, gender, timeliness, completeness) with auto-synchronization based on real-time data upload  - **Custom Report Generation**: Advanced filtering, drill-down functionality to source-level data, and database search across multiple filter  - **User Management System**: Four-tier access control (SSOs with view/edit, SSAs with view/edit, Super Users with view/read, Admin with full permissions) with site-specific data access  - **Data Migration Module**: Import utility for migrating existing Excel data to the new system with dataset upload and merge capabilities for each form - **Push Notifications and Alerts**: Support for push notifications, alerts, and flash message - **Data Connectivity Layer**: Integration with Power BI, APIs, web links, and Excel spreadsheets with secure API authentication and multi-source data triangulation - **Resolution-Independent Design**: Responsive layout automatically adapting to tablets, desktops, and laptops without horizontal scrolling ### Technology Stack - **Frontend**: MS .NET Framework, [PHP](https://www.velsof.com/php-development/), [React](https://www.velsof.com/react-js-development/) Native - **Backend**: MS SQL Server, [MongoDB](https://www.velsof.com/web-development/) - **Mobile**: Native Android SDK - **Server**: Windows Server 2012 R2 (HDD 2TB, NAS Drive 12TB, RAM 16GB, CPU 4-core) - **Styling**: CSS-based page-tree navigation structure - **Security**: Encrypted personal data, secure API authentication, JSIPL data privacy policy compliance ## Implementation Approach The project was delivered in four phases over 9 weeks, followed by an extended maintenance period: **Phase 1 – Foundation (Week 1)** – Inception report with methodology, tools, and Gantt chart – Responsibility matrix and workflow finalization **Phase 2 – Entry-Level Reporting System (Weeks 1-4)** – User authentication with Single Sign-On and admin verification – Development of all 11 forms (Screening + 10 Case Review Forms) in both online and offline modes – Save and Draft functionality for offline data – Automatic synchronization to JSIPL server – Reporting module (essentials) – API integration and server configuration – Testing and bug fixing **Phase 3 – Advanced Features (Weeks 5-6)** – Bug resolution from Phase 1 – Code optimization – Dashboard development – Custom report generation – Old data migration from legacy system **Phase 4 – Field Testing and Rollout (Weeks 7-9)** – Field testing across sentinel sites – Bug fixing based on field feedback – Application rollout and go-live – Exit plan and handover documentation including performance test reports, security test reports, user guidelines, deployment scripts, backup processes, infrastructure design, APIs, and source codes **Maintenance Period (through December 2023)** – 8x7x365 emergency support – Error resolution, patch deployment, updates, and upgrades – Ongoing support for all 32 field staff (16 SSOs and 16 SSAs) ## Key Outcomes & Impact - **Eliminated Legacy System Pain Points**: The new system completely resolved the data loss, lack of save/draft, and storage issues that plagued the open-source predecessor - **Pan-India Surveillance Coverage**: Successfully deployed across 16 sentinel sites in 13 states, providing comprehensive AESI surveillance capability - **Reliable Offline Data Capture**: Field investigators could complete complex clinical forms without connectivity, with automatic synchronization ensuring no data loss - **Accelerated Data Collection**: Streamlined 11-form workflow with interlinkages significantly reduced data entry time compared to the legacy system - **Successful Data Migration**: Historical data from the legacy system was seamlessly migrated, preserving continuity of surveillance records - **Enhanced Vaccine Safety Monitoring**: Real-time dashboards and analytics contributed to COVID-19 vaccine safety profiles and informed emerging safety issue identification - **Contribution to National Policy**: Surveillance findings directly informed MoHFW’s understanding of AESI patterns in the Indian population, supporting evidence-based policy decisions ## Why Velocity Velocity was chosen for this critical COVID-19 vaccine safety surveillance project based on: - **Experience with Health Surveillance Systems**: Demonstrated expertise in building data collection and surveillance applications for public health programs - **Offline-First Design Philosophy**: Proven capability in developing robust offline-capable applications essential for India’s diverse connectivity landscape - **Complex Form Development**: Expertise in developing interlinked clinical data forms with complex validation logic and skip patterns - **Rapid Deployment**: Ability to deliver a production-ready system within 9 weeks, critical for the time-sensitive vaccine surveillance mandate - **Data Migration Expertise**: Proven track record in migrating data from legacy systems while ensuring data integrity and continuity - **Collaborative Working Model**: Willingness to embed dedicated resources at JSIPL and maintain close coordination with the project team throughout the engagement ### Related Services [React.js Development](/react-js-development/)[PHP Development](/php-development/)[Mobile App Development](/mobile-app-development/)