CCL3 and COVID-19: Contrarily, no DML was identified in leukocyte cultures from patients in the MOD group at endpoint A. The hypothesis that B12 downregulates inflammatory genes of COVID-19 via methyl-dependent epigenetic mechanisms was proved by the hypermethylation of three CpGs located in the 5’ UTR region and in the proximal portion of the first exon of CCL3 (Chr17: 36,090,276 - 36,090,005) of leukocytes from cultures of MOD and SEV groups treated with the vitamin.