Abstract
SUMMARYRespiratory syncytial virus and human metapneumovirus are major causes of respiratory illness globally, particularly affecting children and older adults. Despite their clinical significance, substantial gaps persist in understanding the determinants of their transmission. This review examines the multifaceted factors shaping RSV and hMPV transmission, including viral structure and evolution, host behaviors and viral shedding dynamics, the influence of environmental conditions on viral survival, the roles of population- and community-level transmission networks, and the impact of SARS-CoV-2. Additionally, we explore prevention strategies, including immunizations and non-pharmaceutical interventions, to reduce transmission in high-risk settings.