The substance containing small amounts of dead or modified pathogens or their toxins that is injected during an immunization

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.   

Small intestine because that is the organ which absorbs nutrients