NOTE: "...and AirTran was notifying fewer than 20 people who sat in her immediate vicinity, Hirschman said."
And that is why you should NEVER change your seat inflight. At the gate, before you board, from home, YES--AFTER the flight takes off--NO.
I know we're all tempted to jump into that empty row or seat when we see it available after the flight has loaded but this is one reason why you shouldn't. Usually they only go looking for people sitting within x number of rows of the infected person. If they don't know that you moved to within the area they are looking at--they aren't going to call you. Unless it's a biggie story like this one and the TB case where there is media coverage, you could have been exposed to something and never know it. The airline won't provide your name to the Health Dept/CDC/etc if they don't know you were sitting the area of concern. You would be absolutely amazed at the number of people with an infectious disease who board an aircraft each WEEK.
Thats' why I prefer to DRIVE when I can.