Your body builds immunity against the chicken pox virus(Varicella Zoster) after getting affected by it so the risk of developing it again is less. Shingles is a viral infection that causes a painful rash by the same chicken pox virus but this is seen to effect those with a low immunity. Because it is so contagious, a not vaccinated person who is exposed to chickenpox is advised to stay home and away from infants and small children or other non-immune people for 21 days after exposure.