You know what?! My sinuses have been clear as a bell for the last 3 days since I took my flu & pneumonia shot. I had attributed it to the Airborne vitamin doses I was taking for my head cold but now you have me wondering. I CAN BREATHE! The only time my sinuses even drain prior to the shot is when I lay down to go to sleep. Weird, huh! You may just have something there. That's the first I've heard of it though! Hope it lasts anyway!