Lack of Effect of Oral Ribavirin in Naturally Occurring Influenza A Virus (H1N1) Infection

A double-blind placebo-controlled trial of ribavirin was conducted in 97 young adult males naturally infected with influenza virus similar to A/Brazil/I1/78 (H1N1). Ribavirin was given orally at a dose of 1,000 mg/day for five days beginning within 24 or 48 hr after onset of clinical influenza. The clinical signs and symptoms of influenza and quantitative viral shedding were the same in ribavirin- and placebo-treated groups. Ribavirin treatment was associated with significantly fewer fourfold or greater rises in antibody to influenza A viral antigen by the complement-fixation test, while rises in hemagglutination-inhibiting antibody titers occurred with equal frequency in both groups. The ribavirin-treated group experienced significant increases in bilirubin and in reticulocyte counts after onset of therapy.