Immunity duration varies by virus, with measles conferring lifelong protection and others evading antibodies.

“How long immunity lasts depends on the virus. With some viruses, such as measles morbillivirus, which causes measles, infection confers almost universal, lifelong lasting protection. On the opposite end of the spectrum, individuals infected with HIV often have antibodies that do nothing to fight HIV. Some viruses like HIV use multiple strategies to evade antibodies.”