What Immunity to COVID-19 Really Means - Scientific American
It is less clear what those antibody tests mean for real life, however, because immunity functions on a continuum. With some pathogens, such as the varicella-zoster virus (which causes chicken pox), infection confers near-universal, long-lasting resistance. Natural infection with Clostridium tetani, the bacterium that causes tetanus, on the other hand, offers no protection—and even people getting vaccinated for it require regular booster shots. On the extreme end of this spectrum, individuals infected with HIV often have large amounts of antibodies that do nothing to prevent or clear the disease.
Clostridium Tetani - StatPearls - NCBI Bookshelf
It should be noted that infection with C. tetani does not provide immunity, and thus, all patients with the diagnosis of tetanus should receive immunization immediately with three doses of tetanus and diphtheria toxoid.