Conference report: airway mucosal sampling and immune analysis.

Respiratory pathogens cause substantial global morbidity, mortality, and pandemic risk. While parenteral vaccines can effectively reduce severe disease for some respiratory infections, they are often less effective at preventing infection and onward transmission. Vaccines delivered directly to the airways have the potential to induce protective mucosal immunity at the site of pathogen entry. However, progress in mucosal vaccine development has been constrained by limited understanding of airway immune mechanisms, the technical challenges of sampling respiratory tissues, and the lack of standardised, validated immunological assays capable of defining mucosal correlates of protection. To address these challenges, the Novo Nordisk Foundation and Wellcome Trust convened a workshop on airway mucosal sampling and immunological assays, bringing together researchers, clinicians, funders, and representatives from major research consortia. Participants reviewed approaches to sampling the upper and lower respiratory tract, assay technologies, and regulatory considerations for integrating mucosal endpoints into vaccine development. Discussions highlighted major barriers including variability in sampling techniques, low and inconsistent cell yields, limited assay standardisation, and insufficient cross-study comparability. The workshop produced a set of recommendations in four priority areas (i.e., Collaboration, Communication, Consistency and Conduct of research) to share knowledge, accelerate standardisation and validation, and generate evidence supporting mucosal vaccine development. Together, these advances will help strengthen the scientific and regulatory foundations needed to realize the full potential of airway-delivered vaccines for the prevention of respiratory diseases.