Varicella zoster virus or varicella-zoster virus (VZV) is one of eight herpesviruses known to infect humans and vertebrates. VZV only affects humans, and commonly causes chickenpox in children, teens and young adults and herpes zoster (shingles) in adults and rarely in children. VZV is known by many names, including chickenpox virus, varicella virus, zoster virus, and human herpesvirus type 3 (HHV-3).