The 3 genes highly predictive of infectiousness were those encoding transcripts involved in RNA regulation (for example of CXCL10 a key Th1 chemokine implicated in the COVID-19 hyperinflammatory syndrome or cytokine storm28), transcription factor activation, and immune function suggesting that host pathogen relationships are important in the heterogeneity of infectiousness. This evidence concerns the gene CXCL10 and COVID-19.