Hence, the present study assembled serological data on the anti-SARS-CoV-2 IgG response duration of two previous studies and integrated these results with the plasmatic cytokine levels and genetic profiles of 10 immune-relevant SNPs that were also previously published, as well as with the plasmatic total IgG, IgA, and IgM levels, allowing the genetic, clinical, immunological, and epidemiological aspects of the post-COVID-19 IgG response duration to be understood. This evidence concerns the gene CD40LG and COVID-19.