8. Why is the spread of infection slower in real life?
The rate of interactions with other people is typically much less than one interaction every couple of minutes. Also, even when you have contact, you don't always transmit any germs or enough germs to start an infection. If a person does get enough germs to start an infection, it takes a while for the germs to reproduce to high enough levels for that person to become contagious. Notice that this last point links real-life spread of infections to the time it takes for growth of a population of germs inside a person's body. You may want to relate this to the discussion of bacte