It is not necessary to have serological evidence of immunity to varicella-zoster virus (VZV) or a history of previous varicella infection before or after administering zoster vaccine to either immunocompetent or immunocompromised people. Zoster vaccine effectively boosts humoral and cellular immune responses from prior infection. More than 97% of people in Australia are seropositive to VZV by 30 years of age,23 even if they cannot recall having varicella at a younger age.
