I have a question regarding sickness. If 2 people have the same illness (flu, for example), do they still need to avoid spreading bacteria between each other?

I ask because I have 2 roommates, and all three of us began experiencing the same symptoms at the exact same time: itchy throat, cough, etc.

It has now been 3 days and I feel more or less just fine. In fact for the last 3 days, both of my roommates have been becoming sicker and sicker, with a worsening of symptoms, but for me things never got worse.

As a result, I have been somewhat wary of getting too close to them. I try to keep a distance.

Is this a reasonable thing to do? Presumably, we all have the same sickness.