ElasticNet and PLS-R
To identify the key contributing antibody signatures from the data set, elasticNet regression was utilised as previously described19, 38 The Elastic Net hyperparameter was set to have equal weights between L1norm and L2norm i.e. α=0.5. Model performance was evaluated iteratively (1000 iterations, 4 fold cross validation). Partial least squares regression (PLS-R) was performed on ElasticNet-selected antibody features to visualize the relationship between antibody signatures with continuous variables. i.e. Ct (cycle threshold) PCR values (determined via Roche LightCycler 480 Instrument II).