Sex-based differences in the immune response to SARS-CoV-2 were reported in a 2021 paper published in Science [21], which attributed the higher risk of severe disease and death from COVID-19 in males to differences in male vs. female physiology with respect to innate immune cytokines and chemokines (interleukins-8 and 18), type I interferon, T cell activation, sex chromosomes, immune cell transcriptomes, cytokine responses to viral infections, and sex hormones. This evidence concerns the gene CXCL8 and viral infectious disease.