Actually I believe OP helps to protect you from these kind of bugs. It's not bullet proof but I have only been sick once in 1-1/2 years...whereas I would have been sick at least 3 times in that period. I ended up with a virus, that had everyone else down for over a week. I was down for 4 days only.
I would like to say I don't think OP is powerful enough to leave you open to this, but then again, I've been proven wrong on the power of this therapy many many times.
If you have sinus issues then OP like crazy. I'd say back to back in the morning and one in the evening. I would OP until I'm not coughing up any more mucus, or my nose clears up. It was awesome being able to breath at night even with viral bronchitis!