Table 1.

Research domains and illustrative indicators.

Domain	Illustrative Indicators	Number of Indicators in Domain
Country Characteristics	Life expectancies Percent of population aged 65 and older Income group Disease burden	32
Health & Immunization Systems	Insurance systems Registries Financing mechanisms Procurement Providers Barriers to access	>50
Policies & Decision-making	NITAG structures Vaccine-specific recommendations for adults (including target populations, age, by government or other bodies) Immunization laws Country requirements	28
Adult Vaccine Uptake	Vaccine-specific coverage for adults	15
Stakeholders & Champions	Key experts & advocates across medical, healthy aging, and other communities	7

A landscape review of the 34 countries was conducted. Research was divided into five domains and data collected on specific indicators, as illustrated above.