What would working class need to become middle class

It depends basically on how long they can survive if they lost their job: if loosing your job means you are facing eviction if you don't find a job in six weeks then you are working class. If loosing a job means that you might need to sell your car if you don't find a job by next year then you are middle class.

Hope it helps mate:)

geography

this is because warmer climates often don't get people sick from the flu and regions where it was often colder more people received the flu. hope this if you need more reasoning i am here to