Viruses are microscopic germs. They're made up of genetic material encased in a protein coat. Viruses are responsible for common infectious ailments like the common cold, flu, and warts. They also spread diseases like HIV/AIDS, Ebola, and COVID-19. Viruses function similarly to hijackers. They infect healthy cells and use them to proliferate and produce more viruses like themselves. This can cause you to become ill by killing, damaging, or changing your cells. Viruses assault certain cells in your body, including those in your liver, respiratory system, and blood. Virus infections are one of man's most common illnesses. Children are predicted to have two to seven respiratory infections each year, whereas adults have one to three such episodes per year.