Background
Strategic health purchasing is a critical lever for advancing universal health coverage (UHC), particularly in low- and middle-income countries (LMICs). Across Southeast Asia, countries are reforming their purchasing functions to enhance the efficiency, equity, and quality of primary healthcare (PHC). This study assesses the extent and progress of strategic purchasing for PHC in four Association of Southeast Asian Nations (ASEAN) member states: Indonesia, the Philippines, Thailand, and Vietnam.

Methods
We applied the Strategic Health Purchasing Progress Tracking Framework to conduct a structured comparative assessment across five purchasing dimensions: financial management, benefits specification, contracting arrangements, provider payment, and performance monitoring. Data was collected through semi-structured interviews with national stakeholders, supplemented by grey literature and policy document reviews. The data was analysed, triangulated and validated through expert consultation and thematic analysis.

Results
All four countries have taken steps toward institutionalising strategic purchasing through national health insurance (NHI) schemes, though the depth and coherence of reforms vary. Thailand’s universal coverage scheme (UCS) demonstrates the most advanced implementation, characterised by performance-based payment mechanisms and relatively strong monitoring systems. Indonesia and the Philippines are implementing pilots to align payments with service delivery goals, though challenges persist in integrating PHC with broader health system functions. Vietnam maintains high insurance coverage but exhibits limited strategic purchasing practices, particularly for PHC. Across all countries, gaps in data systems and governance capacity constrain effective implementation.

Conclusion
Strategic purchasing reforms in Southeast Asia are progressing but remain uneven in scope and institutional maturity. Strengthening policy coherence, investing in health information systems and aligning public financing with PHC priorities will be critical to advancing these reforms. In particular, Thailand’s experience offers relevant lessons for broader regional efforts to operationalise strategic purchasing for more resilient and equitable PHC systems.