Interplay between Risk Factors of Asthma-Like symptoms, Early-Life Infections, and Risk of Asthma

Asthma-like symptoms, including cough, wheeze, and breathlessness, are common in preschool children and often result in hospitalisation. These symptoms can be a significant burden for the children, their families, and the society. Although risk factors for childhood asthma have been extensively studied, there is a notable gap in research regarding their impact on the prevalence of asthma-like episodes during early childhood and whether such effects vary with age.

Respiratory tract infections (RTIs) are well-known triggers for episodes with asthma-like symptoms in early childhood, which may suggest that risk factors of asthma-like episodes in this period of life could be explained by an increased infection susceptibility. Further, early-life RTIs, especially more severe lower RTIs requiring hospitalisation or physician-attendance, have been linked to the development of asthma and reduced lung function later in life. However, we still need further studies focusing on how the burden of common infections in early childhood, including specific subtypes of infections, influences the risk of developing asthma. Additionally, it is unknown whether the various risk factors exert their asthma associations through an increased burden of infections in early life.
Finally, some studies have suggested a synergistic effect between early-life RTIs and atopy in relation to risk of asthma, but further investigations are needed to fully understand the complex interactions between infection burden, allergic traits, and asthma risk.