Predict: Some pathogens are spread directly from one person to another. This can happen when people come into direct contact or share items, such as drinking glasses. What do you think might affect how quickly a pathogen is spread from person to person?

I think the reservoir ( a human,animal or non living such as soil where the infectious agent normally lives)

secondly the mode of transmission,there are some modes of transmission that allow the pathogen to enter quickly and some that make the process slow.

and also crowding and the presence of co-infections.

i hope this helps