Don't Celtics players ever get flu vaccines? How do we always have several players sick every flu season?
They have as bad an immune system as I do? (Got my flu shot on October 1st, already been sick three times since then.)
That said, last year they got sick in Europe primarily, which may have been a different strain of the flu, and also was early enough into flu season that vaccines might not have been available before they left the States. Otherwise, spending a lot of time in airports, locker rooms, and eating food prepared by others are all good ways to get the myriad of viruses that seasonal flu vaccines don't protect against.