High burden of infections in early life increases asthma risk

Published: April 10, 2024

Common infections in early life are often considered harmless, but they can influence maturation of the immune system, interact with genetic factors, and lead to inflammatory changes in the airways that may increase the risk of asthma. Respiratory tract infections, especially lower and more severe ones, have been linked to a higher risk of asthma. Specific viruses like respiratory syncytial virus and rhinovirus have been identified as key pathogens. Furthermore, the "two-hit hypothesis" suggests that early viral respiratory illnesses combined with aeroallergies significantly increase asthma risk. However, most research has focused on severe respiratory tract infections, with few studies investigating the role of common infections in asthma development.

In a recent publication in The Journal of Allergy and Clinical Immunology: In Practice, Kyvsgaard et al. examined whether a high burden of early life infections conveys an increased risk of childhood asthma from ages 3 to 10 years and affects lung function at age 10 years. They also explored the "two-hit hypothesis" by investigating interactions with respiratory allergies. The researchers followed 700 children from the Copenhagen Prospective Studies on Asthma in Childhood (COPSAC2010) mother-child cohort. The parents recorded common infections in daily diaries from birth up to age 3 years. The children were followed prospectively for the development of asthma and allergies up to age 10 years.  

This new study suggests that children who suffered from a high burden of common infections in early life have an increased risk of asthma up to age 10 years. This association was driven by colds, pneumonia, gastroenteritis, and fever episodes, but not by acute otitis media or tonsilitis. Additionally, children with a high burden of pneumonia in early life had lower long function measures at age 10 years. The study findings also supported the “two-hit hypothesis” showing that children with a high burden of colds who also developed allergic rhinitis had a particularly high risk of asthma, especially those sensitized to molds and house dust mites.

These findings suggest that clinicians should closely monitor children with a high burden of infections in early life for development of asthma symptoms. Controlling early life infections, particularly specific subtypes, may help prevent asthma, especially in children with at risk of allergic rhinitis.

The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.

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