Antigenic Variation

Antigenic variation is a process some pathogens use to evade the immune system. They change certain parts of their surface proteins (antigens), which are the targets our immune system recognizes and attacks. By regularly altering these key features, the pathogen can avoid detection and continue infecting the host, making it hard for the immune system to develop lasting immunity. This strategy is used by organisms like the flu virus and malaria parasites to persist within populations and often explains why vaccines need updates or multiple doses to remain effective.