OBJECTIVE: To generalize existing evidence on the risk factors, preventive measures, and long-term outcomes of lower respiratory tract infections (LRTIs) during early childhood and to identify the main gaps in research and policies. DATA SOURCES: The search took place in PubMed, Scopus, and Web of Science, covering studies published between January 2000 and August 2025, which were complemented with reports by WHO, UNICEF and GBD database. STUDY SELECTIONS: The included studies included randomized controlled trials, cohort, case-control, cross-sectional studies and systematic reviews including children of age 0-5 years. The researches on acute treatment alone or the adult population were excluded. RESULTS: Causes of LRTIs in early life are caused by determinants which interact with each other, in this case, preterm birth, malnutrition, indoor air pollution, insufficient immunization, and socioeconomic inequities. Prevention measures, which include vaccination, maternal immunization, exclusive breastfeeding, micronutrient supplementation, and consumption of clean fuels, have an important role in lowering the morbidity and mortality rate among children. There is also evidence of the persistence of health effects of early LRTIs, such as asthma, impaired lung function, neurodevelopmental delay, and increased cardiometabolic risk. CONCLUSION: Early-life LRTIs are not merely an acute health burden but also lifelong respiratory and systemic outcomes. To reduce both short-term and long-term effects on the global population, it is necessary to widen fair vaccination coverage, enhance maternal-child diet, manage environmental risks and increase health-system capacity.
M et al. (Wed,) studied this question.