I am on my 3rd year of flying mostly 777, on two different airlines. Never it happened to me to feel anything strange. Never it happened to me to have a pax feeling unwell, apart of the usual gastroenteritis or indigestion.
I'd rather say that I feel better after flying 777 than any other AC (maybe because of its nice bunks
).
What I have been trying to understand if it is a mass suggestion or...well, the world is split between Airbus and Boeing...where do you belong to???