Strengthening Primary Health Care Through Implementation Research: Strategies for Reaching Zero-Dose Children in Low-...

Area of Science:

• Global Health
• Implementation Science
• Public Health Policy

Background:

• Persistent immunization gaps affect millions of infants and children globally, particularly in low- and middle-income countries (LMICs).
• Zero-dose (ZD) children, who have not received even the first DTP vaccine, and those missing measles doses highlight significant inequities and barriers in healthcare access.
• Addressing these disparities necessitates innovative, context-specific approaches to strengthen primary health care (PHC) and reach marginalized populations.

Purpose of the Study:

• To document and synthesize implementation research (IR) projects focused on immunization programs in LMICs.
• To identify critical enablers and effective strategies that reduce inequities and improve immunization outcomes, specifically for ZD children.
• To provide actionable insights for advancing the Immunization Agenda 2030.

Main Methods:

• A retrospective multiple-case study design analyzing 36 IR projects across 13 LMICs.
• Data collection involved systematic document reviews and validation discussions with project leads.
• Extracted strategies (n=326) were coded and mapped to the WHO-UNICEF PHC Levers for Action framework, followed by descriptive analysis.

Main Results:

• Most identified strategies (76.1%) aligned with operational PHC levers, emphasizing monitoring, evaluation, workforce development, and models of care.
• Digital technologies (11.7%) were increasingly used for real-time tracking, while community engagement (8.9%) and governance (7.7%) emerged as crucial enablers.
• Projects showed improvements in microplanning, data systems, community trust, and health system capacity, though sustainable financing (4%) remained a challenge. Few projects directly targeted ZD children (n=3).

Conclusions:

• Reaching ZD children demands equity-focused strategies integrating digital innovation, community engagement, and robust system planning.
• Strengthening governance, financing, and research is essential for sustained progress in immunization coverage.
• Implementation research provides valuable, context-specific evidence to reduce equity gaps and enhance global immunization efforts.