Varicella-zoster virus-specific cellular immunity in subjects given acyclovir after household chickenpox exposure

The time course of primary cell-mediated immune responses to varicella-zost er virus (VZV) among persons receiving acyclovir prophylaxis after exposure to chickenpox has not been well defined. Fifteen children who had househol d exposure to varicella received prophylactic acyclovir (40 mg/kg/day for 7 -14 days after exposure) and were studied for development of both antibody and cell-mediated immunity (CMI) to VZV. Twelve developed antibodies and/or CMI; 10 had no symptoms and 2 manifested mild varicella, Two were already immune to varicella and had booster immune responses. One was not infected and subsequently developed full-blown varicella, Although acyclovir given a fter exposure to VZV is highly effective and does not appear to attenuate t he immune response, it remains necessary to confirm whether, in the absence of clinical varicella, persons acquire specific immunity.