TLR4 and COVID-19: Considering that expression of TNF-α [5, 7] and TLR4 [10] has been reported to be elevated in COVID-19 patients and that DNA methylation is associated with decreased gene expression, we predicted that methylation of these promoters would be decreased; however, our results demonstrated an increase in the percentage of methylation of the promoters of both genes in COVID-19 patients, and the severity of disease was associated with a higher percentage of methylation of the TNF-α promoter.