You won't necessarily be more susceptable forever. But you will be for a while. Depending on how hard you get hit, it could take months for your immune system to recover.

I had regular acupuncture and I take chinese herbs that support the lungs and sinuses whenever I get a cold. I also do a regular nasal cleanse. I'm pretty careful about keeping my sinuses happy because it seems like that where it all starts from and ends up in my lungs.

If you're interested in the food side of things there is a great book called Healing with Whole Foods that is based on traditional Chinese medicine/naturopathic approaches to using regular food as medicine.