A placebo-controlled trial of a proprietary extract of North American ginseng (CVT-E002) to prevent acute respiratory illness in institutionalized older adults.

Objectives: To compare a proprietary extract of American ginseng, CVT-E002, with placebo in preventing acute respiratory illness (ARI) in an institutional setting during the influenza season.

Design: Two randomized, double-blind, placebo-controlled trials conducted late in the 2000 (8 week) and 2000-2001 (12 week) influenza seasons.

Setting: Long-term care setting that included nursing home and assisted living at three sites.

Participants: Eighty-nine (2000) and 109 (2000-2001) enrolled subjects, average age 81 and 83.5, respectively; 74% women. Approximately 90% had received influenza vaccine in each of the 2 years.

Intervention: Oral twice-daily administration of a proprietary ginseng extract, CVT-E002, 200 mg or placebo.

Measurements: ARI was defined as two new respiratory symptoms or one with a constitutional symptom. Confirmation of viral ARI was by culture (influenza or respiratory syncytial virus (RSV)) or serology for influenza. Laboratory safety monitoring was done at 0, 4, and 8 or 12 weeks.

Results: An intent-to-treat analysis of pooled data corrected for drug exposure time showed that the incidence of laboratory-confirmed influenza illness (LCII) was greater in placebo- (7 cases/101 subjects) than CVT-E002-treated (1/97) groups (odds ratio (OR)=7.73, P=.033). Combined data for LCII and RSV illness were also greater in placebo- (9/101) than CVT-E002-treated (1/97) groups (OR=10.50, P=.009), for an overall 89% relative risk reduction of ARI in the CVT-E002 group.

Conclusion: CVT-E002 was shown to be safe, well tolerated, and potentially effective for preventing ARI due to influenza and RSV.