CMX001 is an orally administered lipid conjugate of the synthetic nucleotide analog cidofovir (CDV). The conjugate is believed to be absorbed in the small intestine then delivered to target organs throughout the body where it crosses cell membranes by facilitated and passive diffusion. Inside the cell, CMX001 is cleaved by intracellular phospholipases to release CDV which is converted to the active antiviral agent, CDV-diphosphate (CDV-PP), by intracellular anabolic kinases. Adults and adolescents, regardless of viral infection/disease, will have a maximum weekly dose of 200 mg i.e., 200 mg once weekly OR 100 mg twice weekly; not to exceed 4mg/kg total weekly dose. Pediatric subjects (< 12 years), regardless of viral infection/disease, will have a maximum weekly dose of 4 mg/kg i.e., 4 mg/kg once weekly OR 2 mg/kg twice weekly.