Lack of harmonisation in immunological data: challenges in synthesising data during the COVID-19 pandemic.

The COVID-19 pandemic drove the rapid development of assays to ascertain immune responses, and laboratories were required to adapt to difficult and quickly changing circumstances. While flexibility and innovation were essential, they also introduced heterogeneity in methods, reagents, and reporting practices between labs. This lack of harmonisation made it difficult to compare findings across studies, slowing evidence synthesis, and limiting the usefulness of data for modelling efforts and policy guidance. Drawing on our team's experience synthesising and modelling vaccine immunogenicity data during the pandemic, we discuss the long-term challenges of standardising human immunology research that were highlighted by the COVID-19 pandemic. We argue that vaccine immunogenicity studies require standardised reporting and quality assessment tools. We propose practical solutions to support comparability of laboratory-based practices, while preserving methodological diversity. By implementing changes before the next public health crisis, future research can avoid waste, strengthen certainty, and maximise policy and practice impact.