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-zoster virus (VZV) among persons receiving acyclovir prophylaxis after exposure to chickenpox has not been well defined. Fifteen children who had household 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 after exposure to VZV is highly effective and does not appear to attenuate the immune response, it remains necessary to confirm whether, in the absence of clinical varicella, persons acquire specific immunity.