There are six points at which the chain of infection can be broken or interrupted and a germ can be stopped from infecting another people. The six links are the infectious agent, reservoir, portal of exit, mode of transmission, portal of entry, and susceptible host. If one of the link is broken or interrupted, no infection occurs in the body of an individual because all the links are attached to each other in the form of chain which can stop working if one of it stop working.