Comparison of specific immunities to varicella-zoster virus following post-exposure prophylaxis of varicella by oral acyclovir observed in a family

An otherwise healthy 3-year-old girl developed severe varicella complicated by aseptic meningitis and received intravenous acyclovir (ACV) therapy. Her two siblings who were susceptible to varicella-zoster virus (VZV) and closely exposed to VZV in the family received oral ACV (45 or 54 mg/kg per day in four divided doses for 7 days) starting 8 days after onset of the index case for post-exposure prophylaxis of varicella. They showed only five or seven papules over the body without fever 12 days after onset of the index case, while they had one-third or half the level of antibody titer and equal sized skin reactions to VZV antigen of the index case 2.5 months later.