The Blue Germ makes man and animals immune to disease and aging -- and desire and ambition. The narrator is one of the inventors, and was not expecting ambition to be lost; but then he wasn't expecting the uninfected young to systematically slaughter the old, who own almost all property, either.
It's not a very *gripping* novel, all the same -- there's not much done with the difference of affect as the narrator catches the disease, or with the characters of the few who catch it and aren't undone:
Those who still retained sufficient individuality to continue existence were the strangest mixture of folk, for they were of every class, many of them being little better than beggars. They were people in whom the desire of life played a minor part. They were those people who are commonly regarded as being failures, people who live and die unknown to the world. They were those people who devote themselves to an obscure existence, shun the rewards of successful careers, and are ridiculed by all prosperous individuals.
and it ends "and then everybody got over it and woke up", cutting off the narration rather than working out any of the psychological or political effects one would expect. So; mildly interesting as a precursor of's Holy Fire, etc., but not so much in itself.
Project Gutenberg file #26852: The Blue Germ