In contrast to previous unsupervised hierarchical clustering for IgA, IgM and IgG (Fig. 4a–c) to multiple SARS-CoV-2 antigens, these four SARS-CoV-2 Ab features had distinct patterns in COVID-19 patients, which led to the clustering of COVID-19 patients together with a single exception, this notably being the healthy, exposed, SARS-CoV-2 PCR-negative individual (Fig. 4d). This evidence concerns the gene CD40LG and COVID-19.