Given that she kissed me for about 5-7 seconds one week after she had gotten a cold sore, what's the risk that I may get it as well? It has been about 3 and half days since this interaction happened. In the last day, I have developed a mild sore throat, my head feels a little zoned out and my body feels tired.  I'd appreciate any advice.

I think the exposure that you had to this virus was incredibly minimal.  5-7 seconds with a peck is almost certainly not going to infect you with HSV 1 the cause of cold sores.  It takes more exposure for a longer period of time than that.  If you were going to get symptoms, and have truly never been infected before, you would develop sores on this lip within 2-10 days of the exposure.  I think you might be over-noticing symptoms at this point, do you think that's a possibility?

Terri

Given that it was about 7 days after my friend had gotten her cold sore, is that enough time for the cold sore to have  healed completely? She certainly seemed to think that it was gone.

It sounds like maybe you picked up some other little virus or your worry is really getting you down. 

Yes, 7 days with no cold sore certainly is healed.

Terri