The flu, like a cold, is a respiratory infection but is caused by an entirely different group of viruses - namely the influenza A, B and C viruses. Perhaps the best way to prevent the flu is to get an annual flu shot before the flu season hits.
I called Lufthansa, and they told me that there are Economy Plus seating sections on the Bangalore to Frankfurt and Frankfurt to Chicago legs. But, since I bought tickets through United, they told me I can't get any seat assignments until check-in in Bangalore unless I work with United.
The number of seats abreast is affected by the aircraft width. On very small aircraft such as the Beechcraft 1900 there are only individual seats on each side of the aisle (1+1 seating). The widest narrow body aircraft such as the Airbus A320 and Boeing 737 have six abreast seating in a 3+3 layout. Asymmetrical layouts also exist, the Embraer Regional Jets have 1+2 seating while the Douglas DC-9 aircraft typically feature 2+3 seating.