Efficacy and Safety of CVT-E002, a Proprietary Extract of Panax quinquefolius in the Prevention of Respiratory Infections in Influenza-Vaccinated Community-Dwelling Adults: A Multicenter, Randomized, Double-Blind, and Placebo-Controlled Trial
CVT-E002 (a proprietary extract) was found to be effective in the prevention of upper respiratory infections (URIs) in healthy adults, and institutionalized and community-dwelling seniors. A multicenter, randomized, double-blind, placebo-controlled trial was carried out to determine effects of CVT-E002 in the prevention of URIs in influenza-vaccinated community-dwelling adults. 783 community-dwelling adults were randomized to receive placebo, 400？mg or 800？mg treatment/d (1？:？1？:？1) for 6 months. Primary analysis on the incidence of laboratory-confirmed-clinical URIs (LCCUs), including influenza A and B, was performed on those receiving at least one dose. Secondary analysis was performed on study completers and included incidence, severity, and duration of URIs meeting a Jackson-based criteria and safety of CVT-E002. The incidence of LCCUs in the ITT group was 5.5%, 5.2%, and 4.6% in the placebo, 400？mg and 800？mg groups, respectively ( ). Jackson-confirmed URIs were significantly lower in the treated groups ( ). CVT-E002 supplementation reduced the severity and duration of Jackson-confirmed URIs. The results indicate that CVT-E002 can be safely used by similar groups and may prevent symptoms of URIs; larger sample size is warranted. 1. Introduction Viruses are important causes of morbidity and mortality in elderly patients, and respiratory viral infections, particularly influenza, remain a significant cause of death in community-dwelling older adults. Influenza vaccination may have limited efficacy in this population, possibly due to age-associated declines in both humoral and cell-mediated immune responses [1, 2]. Cases of influenza in influenza-vaccinated seniors represent vaccine failure, and a therapy that can enhance the anti-influenza response in influenza-vaccinated seniors would be of therapeutic benefit in this population. CVT-E002 (COLD-FX？), a patented poly-furanosyl-pyranosyl-saccharide-based extract of Panax quinquefolius is known to have immunomodulatory properties [3, 4]. Evidence from numerous in vitro and animal studies indicates that CVT-E002 acts through Toll-like receptors to stimulate both innate and acquired immunity and enhance immune responses to viral infections.For example, in a study of human peripheral blood mononuclear cells cultured with live influenza virus, CVT-E002 was found to enhance the production of IL-2 and IFN-γ [4]. In another study, CVT-E002 increased the expression of IFN-γ in natural killer (NK) cells cultured with influenza virus (Y. A. Jing, Internal report). Daily administration of CVT-E002 for 6 weeks to
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