Treatment of adult varicella with oral acyclovir. A randomized, placebo-controlled trial

To assess the efficacy of oral acyclovir in treating adults with varicella and to describe the natural history of adult varicella.

Double-blind, placebo-controlled randomized trial.

A naval hospital.

One hundred forty-eight of 206 consecutive adult active duty Navy and Marine Corps personnel who were hospitalized for isolation and inpatient therapy of varicella and who could be treated within 72 hours of rash onset completed the study. The diagnosis of varicella was confirmed by acute and convalescent serology in 143 of 144 patients with available paired sera.

Patients were randomly assigned to receive either acyclovir, 800 mg orally five times per day for 7 days, or an identical placebo. Separate randomization codes were used for patients presenting within 24 hours of rash onset and for those presenting 25 to 72 hours after rash onset.

Daily lesion counts, symptom scores, temperature measurements, and laboratory tests were used to monitor the course of the illness.

Early treatment (initiated within 24 hours of rash onset) reduced the total time to (100%) crusting from 7.4 to 5.6 days (P = 0.001) and reduced the maximum number of lesions by 46% (P = 0.04). Duration of fever and severity of symptoms were also reduced by early therapy. Late therapy (25 to 72 hours after rash onset) had no effect on the course of illness. Only four patients had pneumonia, and no encephalitis or mortality was noted.

Early therapy with oral acyclovir decreases the time to cutaneous healing of adult varicella, decreases the duration of fever, and lessens symptoms. Initiation of therapy after the first day of illness is of no value in uncomplicated cases of adult varicella. The low frequency of serious complications of varicella (pneumonia, encephalitis, or death) precluded any evaluation of the possible effect of acyclovir on these outcomes.