This is about bacterial infections and antibiotics. As far as I know that topic is unrelated to viruses or vaccines.

EDIT: People below pointed out that regardless of the common conflation of bacteria and viruses in regard to antibiotics, the point here is that when we don't fully eradicate either bacteria or viruses they can come back stronger. These are known phenomena.

This is about bacterial infections and antibiotics. As far as I know that topic is unrelated to viruses or vaccines.