What can we learn from the Spanish Flu?

They probably don't understand either 1. what the nightmare is about or 2. his anxiety and stress

You did not show us the image of the burger, but i shall try to answer as best i can.  when purchasing food, always consider the ingredients as well as the person who prepared it. consider if they were hygienic people or not, in case the burger was infected with bacteria. no mortal should place an infected burger into their mouth.   

Don't pollution air circulation. wasting pollutionclean in your surroundings