The incidence of complement-fixing antibody to varicella-zoster virus in hospital patients and blood donors.

The sera of 308 patients, not suffering from varicella or zoster infections, and the sera of 183 blood donors were examined for complement-fixing antibody to varicella-zoster virus. In both groups about 70% of sera from persons aged 11-40 years had antibody titres >/= 1/4; the incidence was less in the age range 41-60 years and increased in later decades. Antibody titres of 1/16 or 1/32 were noticeably less frequent in those aged 41-60 years than in younger or older groups.It was concluded that an unchanging titre of 1/16 or 1/32 was of no diagnostic significance. The age distribution of antibody was consistent with the theory that zoster only occurs when antibody has declined.