Vaccines and Viruses: Design and Development of Vaccines - Hardcoverby Abrianna Bentley (Editor) A virus is a microorganism that functions and replicates only inside the living cells of other organisms known as host cells. It causes damage to the host cells and often kills the host cell in the process. Some common examples of human diseases caused by viruses are common cold, SARS, influenza, chickenpox, cold sores, rabies, Ebola virus disease, AIDS (HIV), avian influenza, etc. Vaccinations are the most effective