Shingles (herpes zoster) is caused by the same virus that causes chickenpox, the varicella-zoster virus (VZV). During an active rash, a person experiencing shingles is contagious. This means that he can infect others with VZV, so a child who has never had chickenpox can contract VZV at this time.
Once a person contracts VZV, the infection never fully clears and can become active again later, leading to shingles. Shingles causes a rash with blisters as well as pain along the path of the nerve in which it has become active again.
Close contact with the rash caused by shingles can lead to infection with VZV, according to the Mayo Clinic. A child who contracts VZV from a shingles rash will develop chickenpox, not shingles.
It is not possible to pass VZV to someone who has already had chickenpox, according to the Mayo Clinic. This is because immunity to the virus develops after initial infection.
Pregnant women who have never had chickenpox should also avoid contact with people who have shingles. This is because the child of a woman who has shingles during pregnancy can develop birth defects ranging from scarring to mental retardation, according to the March of Dimes.
Adults who are vaccinated for shingles may develop a rash as a result. This rash has not been shown to be infectious, but the Centers for Disease Control and Prevention recommends covering this rash.