The mechanisms and associated factors underlying the heterogeneity of the IgG response duration after SARS-CoV-2 infection are poorly understood, but it is probable that genetic backgrounds have a role, as some studies have associated gene polymorphisms in the IL-6 pathway [14,15], among other pathways, with the COVID-19 IgG response in vaccination [16,17], along with other biological factors like comorbidities and COVID-19 severity [18,19,20]. This evidence concerns the gene IL6 and COVID-19.