evidence: Viral infections are any illness you get from a virus (a small germ that uses your cells to reproduce). Common viral illnesses include colds, the flu, COVID-19, norovirus ("stomach flu"), HPV (warts) and herpes simplex virus (cold sores). Many viruses go away on their own, but some cause life-threatening or chronic illnesses. Viral infections are illnesses you get from tiny organisms that use your cells to make more copies of themselves (viruses). Viral infections commonly cause respiratory and digestive illnesses, but viruses can also infect most other parts of your body. A virus is a type of germ (pathogen) that’s so small, you can only see it under a microscope. All viruses carry a small piece of genetic information (DNA or RNA) inside a protective coating (capsid). You can think of it like an envelope carrying instructions. Our cells, on the other hand, are like an entire factory: They contain instructions and all the equipment needed to carry them out. These instructions tells us how to build proteins and make more cells.