Defining hard-to-reach populations for vaccination

Area of Science:

• Public Health
• Vaccinology
• Health Equity

Background:

• Equitable vaccine access requires identifying underserved populations.
• Clear definitions of "hard-to-reach" populations are essential for resource allocation and intervention strategies.
• Existing literature lacks formal definitions and clear criteria for classifying these groups.

Purpose of the Study:

• To review existing definitions of "hard-to-reach" populations in vaccination efforts.
• To differentiate between "hard-to-reach" and "hard-to-vaccinate" populations.
• To propose a framework for defining "hard-to-reach" populations based on supply-side barriers.

Main Methods:

• A comprehensive literature review was conducted.
• Analysis focused on identifying formal definitions and usage of "hard-to-reach" population criteria.
• Proposed definitions were developed based on identified gaps and barriers.

Main Results:

• A significant need exists to distinguish between populations that are hard to reach and those that are hard to vaccinate.
• Current literature inadequately defines "hard-to-reach" populations, lacking clear classification criteria.
• Proposed definition for "hard-to-reach" populations focuses on supply-side barriers like geography, mobility, discrimination, and inadequate healthcare systems.

Conclusions:

• "Hard-to-reach" populations face supply-side barriers (e.g., geography, conflict, provider discrimination) hindering vaccine access.
• "Hard-to-vaccinate" populations face demand-side barriers (e.g., distrust, poverty, lack of awareness).
• Further research is needed to refine definitions, measure impact, and develop targeted interventions for these distinct groups to improve vaccination coverage.