How has the immune system evolved to function optimally in the presence of multiple pathogens? The immune system must operate in a highly variable environment in which coinfection is the norm and resources are frequently limiting. Traditionally, however, research has sought to understand host immunity in the context of a single pathogen under defined conditions. It is increasingly clear that removing one set of pathogens in a co-infection or altering commensal populations can generate a void exploited by other pathogens, leading to an imbalanced immune response, with potential for immunopathology including autoimmunity, allergy and asthma. New therapeutic strategies and vaccination approaches must address the need for optimal immunity in real world conditions to avoid these adverse immune consequences or the emergence of new pathogens. This article was published on 2025-03-12
