Hi Emily Rose, I do not have any data to back this up, just my personal experience. Because I am so constantly exhausted it seems like I just catch about anything or bug that seems to be making the rounds. The last two winters I have had bouts of pneumonia that have begun with just simple cases of bronchitis. It seems to take stronger and longer amounts of antibiotics to recover. I do get a flu shot every year, especially since I spend my days in college. I just seem to be all over weaker than I was pre RSD. I am sure you will get much better answers than mine soon. Lisa