Good afternoon

I had a blood test done yesterday morning and the puncture site was left looking red and sore today - no blood though.  I showed it to a colleague of mine who without thinking touched it with an unwashed hand.  I am not worried that he might have somehow infected it. 

Could you please tell me if that could be possible considering  that the blood test was done 24 hours earlier and there was no post blood test bleeding from the puncture site?

Thank you