Can you tell me how high are my chances of developing chickenpox from someone with shingles?

Rare but possible: The shingles patient can only spread the germ through contact with the debris, not through saliva or a cough as would be the case with chickenpox.Also, at a listed age of 50, your chance of never having Cpx as a kid are less than 4%, even if you don't remember it. A simple blood test could prove you once had Cpx and are immune.