Why is it that most people get chicken pox only once but they can get a cold or flu over and over again throughout a lifetime?

Chicken pox is caused by the varicella-zoster virus, which typically provides lifelong immunity after the first infection. In contrast, colds and flu are caused by different viruses that can mutate and evolve, leading to different strains circulating each year. This variation in strains allows for reinfection with colds and flu multiple times throughout a person's life.