Report from the World Health Organization's immunization and vaccines-related implementation research advisory committee (IVIR-AC) meeting, virtual gathering, 17-21 February 2025.

The Immunization and Vaccines-related Implementation Research Advisory Committee (IVIR-AC) serves as the World Health Organization's (WHO) key advisory body for independently reviewing research that assesses the impact and value of vaccines, particularly using transmission and economic modeling analyses. During its first semi-annual meeting of 2025, held on 17-21 February and complemented by ad hoc sessions on 5 February, 11 April and 14 April, IVIR-AC provided feedback and recommendations across seven key sessions. This report summarizes the discussions and outcomes of the meeting. Topics covered included immunization research priorities in the WHO Eastern Mediterranean region, multi-model comparisons of typhoid conjugate vaccine schedules, a malaria intervention multi-model comparison, a full value assessment of invasive non-typhoidal Salmonella (iNTS) vaccination, an evaluation of improved influenza vaccines, vaccine impact modeling under the Immunization Agenda 2030 (IA2030) framework, and combination vaccines value assessment.