The Influence of Climate and Air Pollution on Pneumococcal Dynamics: A Scoping Review

Despite widespread pneumococcal vaccination, disease burden remains substantial with unexplained seasonal patterns. Understanding how environmental exposures influence pneumococcal transmission and disease is critical amid climate change and increasing human mobility. This scoping review synthesizes evidence from 72 studies spanning five decades, including epidemiological analyses, human-challenge and animal models, and in-vitro experiments, examining quantified environmental factors such as air pollutants, meteorological variables, and passive cigarette smoke (PCS). Effects of ambient air pollution are heterogeneous, impacting colonisation, invasive disease, bacterial burden, biofilm formation, and lung translocation, with evidence for impairment of key immune cells. PCS consistently increases both colonisation and invasive disease risk. Meteorological factors, including temperature, humidity, and rainfall, vary by climatic zone with evidence gaps in tropical regions. Overall, environmental factors substantially affect pneumococcal dynamics, but effects are heterogeneous. Further elucidating these interactions will be essential for predicting how climate and environmental factors can alter disease patterns.