What can I take to prevent a cold while pregnant? UPDATE!

TTC #2 due 3/29

3 year old has running nose looks like he has a cold coming on. What can I take to help me to not get sick? Already taking prenatals.

Zicam or Air born? Extra vitamin C? Nothing?

Last pregnancy I got a cold and it lasted 16 weeks so I am really paranoid about getting a cold right now!

Update- Airborne and Zicam are a no go during pregnancy!

Anyone have home remedies that actually work for fighting or preventing colds?