Is Nemesis really about the polio epidemic - or something else?

Re-reading Philip Roth's most-recent novel, "Nemesis," which is our book-group selection for this month, and find it just as great or even better second time through - also makes an interesting contrast with his first novel, Letting Go (1962), which I just finished: where LG was long and somewhat unfocused, Nemesis is very tightly constructed, focuses on one summer (1944) and the life of one young man, Bucky Cantor, a gym teacher and playground director, during a polio epidemic in Newark (was there really an epidemic that summer?), as one after another youngsters in Newark catch the contagious disease and die, Bucky, tormented by guild because he was rejected for military service and his two best friends are fighting in Europe, has to decide whether to stay on as summer playground director or take a job in a summer camp and get to be with his fiancee. He's a really complex Rothian character: he wonders about the cruelty of a god that would allow a disease like polio, he is clearly driven to be noble and heroic to compensate for his family background (his dad was a thief, who abandoned him at childbirth), he is drawn to his fiancee and her family because of their much higher social stature - clearly looking for a father figure in her dad - and he ultimately makes the choice to go to the camp - and as he enters it is clear to him, and to us of course, that the camp in the Poconos is another world, clean and cool and privileged, not the tough streets of Newark, sweltering and infectious, sounds of sirens in the night. But is he safe? Can you escape the disease? And most important - is it really polio that Roth is writing about, or something else? Notably, there's not a word in the novel (at least first half) about the Holocaust and the murder of the Jews in Europe.