WHY are there many drugs against bacterial infections and few against viral ones? A bacterium is an integral single-celled organism which biochemistry is quite different from that of humans. Therefore, it is possible to find drugs that block the enzymes vital for bacteria or destroy their cell wall, while being harmless or minimally toxic for humans. A virus, on the other hand, is much simpler, and after infecting the target cell, it has nothing of its own except for the genome. Genome duplication and synthesis of viral proteins are performed by the same molecular mechanisms of the infected cell that ensure the vital activity of healthy cells.