the virus

A virus is a tiny infectious agent that cannot reproduce on its own. It needs to invade living cells—such as those in humans, animals, or plants—and hijack their machinery to make more copies of itself. This process damages or destroys the infected cells, which can cause symptoms of illness. Viruses are made of genetic material (DNA or RNA) enclosed in a protein coat. They are responsible for many diseases, including the common cold, influenza, and COVID-19. Vaccines and antiviral treatments help prevent or reduce the severity of viral infections by strengthening the immune response or inhibiting the virus's ability to replicate.