June 26th, 2025

Massachusetts MIIS Leads the Nation in VTrckS API Phase 3 Implementation

CDC Recognizes SSG and Massachusetts MIIS as First in Nation to Implement VTrckS API Fully

NEEDHAM, Mass., June 9, 2025 — In a landmark achievement for Immunization Information Systems (IIS) modernization, the Massachusetts Immunization Information System (MIIS), working with the team at Strategic Solutions Group (SSG) LLC, became the first jurisdiction to successfully go live with Phase 3 of the VTrckS API. This milestone marks a significant shift from legacy file-based processes to real-time, automated data exchange with the CDC’s Vaccine Tracking System (VTrckS). SSG was also among the first to implement Phase-1 and Phase-2 and automate the vaccine shipment data importing from CDC to IIS.

Project Background and Phased Rollout

The CDC’s VTrckS API was designed to modernize the vaccine ordering and tracking process, eliminating the need for manual flat-file uploads/downloads from VTrckS system. Instead, it supports secure, programmatic interactions between awardees’ IIS and the VTrckS system. The rollout occurred in three phases:

Phase 1: Shipment and status data (VTrckS to IIS) – completed in April 2024
Phase 2: Federal, non-federal, pandemic vaccine lists, and county codes (VTrckS to IIS) – completed in April 2024
Phase 3: IIS To VTrckS Data Export of Provider Master Data, Inventory on Hand, Provider Orders, Vaccine Returns, and Vaccine Wastage – completed in April 2025

Massachusetts’ implementation of Phase 3 marks the first time a jurisdiction has sent outbound VTrckS transactions directly from its IIS, closing the loop for end-to-end API-based data exchange.

Implementation Timeline

The team followed a disciplined project timeline, which included:

Completing provider and system-level onboarding with the CDC
Submitting and receiving approval for IEA and access forms
Performing integration testing for each Phase 3 interface
Conducting multi-round testing to include positive, negative, and bulk cases
Going live after CDC validation of test results and production readiness

Integration Testing Strategy

The team approached testing in structured three-cycle sequences for each service:

Cycle-1: Basic functionality – at least 15 unique records submitted
Cycle-2: Positive/negative test cases across field combinations
Cycle-3: Bulk testing of 30–40 records per submission to simulate production

Each service—Provider Master Data, Inventory, Orders, Returns, and Wastage—was validated against extensive CDC business rules. The team used the CDC’s published testing templates and provided test data for verification after each cycle.

Notably, the SSG team also validated dependency timing, initiating Inventory or Order submissions just seconds after Provider Master Data calls, ensuring robustness under real-world processing latency.

Overcoming Technical and Operational Challenges

The key to success was a deep understanding of the VTrckS API Specification Guide, including asynchronous processing, authentication, and error handling requirements.

Among the challenges:

Ensuring the correct mapping of all data fields
Managing asynchronous calls and Run Status tracking
Maintaining parallel production and testing access for CDC-funded technology partners while securing credentials, SAMS IDs, and encryption

The SSG team collaborated closely with the CDC on error response handling and conducted dashboard demonstrations to illustrate automated resubmission logic and internal monitoring. SSG implementation also exceeded the requirements set by the CDC.

Impact and Lessons Learned

This go-live represents a foundational leap in IIS modernization—bringing near real-time transparency, reducing manual processing, and ensuring higher data accuracy. These efforts lay the groundwork for other jurisdictions.

SSG has identified bugs during integration testing and helped the CDC fix and improve the Phase-1, 2, and 3 APIs. This is helping other jurisdictions that were onboarded later to have a smoother integration.

Key takeaways:

Plan for at least three integration cycles per service
Test sequencing across services to validate dependencies
Include both structured and edge-case data in test sets
Ensure staff training on interpreting API error responses and CDC Run Status outputs

Conclusion

SSG is proud to have partnered with The Massachusetts MIIS team and pioneer the first full outbound integration with VTrckS using the new API. As more jurisdictions look to modernize their systems, the hope is that this experience provides a blueprint for success—reinforcing the importance of rigorous testing, stakeholder engagement, and agile adaptation.

The Massachusetts Immunization Information System team at Strategic Solutions Group looks forward to the continued collaboration with the CDC and the broader IIS community to realize the vision of a fully integrated national immunization infrastructure.

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About Strategic Solutions Group:

SSG is a leader in public health technology, offering innovative solutions like immunization information systems, disease surveillance systems, and early childhood intervention data systems. SSG utilizes its Casetivity platform, an award-winning solution for public health, to modernize public sector workflows, help public health departments optimize operations, and improve public health outcomes.