What if you get Hepatitis A one week after getting the vaccine (1st series)?

I got my first series shot for Hep. A, today. I leave for China in one week. That means I will be unprotected from Hep. A during my first week in China.

What if I get Hep. A during that first week. Would the shot have been pointless, or will the antibodies help me out when they finally DO activate?
Also, if the antibodies do fight the virus during the 2nd week (when activated), will I never be able to give blood again b/c of having Hep. A, or did I never have it in the 1st place since it was fought off?