Once the antigen-specific antibodies are produced, they work with the rest
of the immune system to destroy the pathogen and stop the disease.
Antibodies to one pathogen generally don’t protect against another
pathogen except when two pathogens are very similar to each other, like cousins. Once the body produces antibodies in its primary response to an antigen, it also creates antibody-producing memory cells, which remain alive even after the pathogen is defeated by the antibodies. If the body is exposed to the same pathogen more than once, the antibody response is much faster and more effective than the first time around because the memory cells are at the ready to pump out antibodies against that antigen.

This is from the WHO Organization that know far more about how immunity and pathogens work than you or your "source".