Echinacea (Quick Defense) and identical placebo capsules will be manufactured by Gaia Herbs (Brevard, NC). Gaia Herbs will conduct an analysis of their product to verify supplement content. Two echinacea capsules will contain the equivalent of 250 mg E. purpurea root and 83 mg E.angustifolia root standardized to 10 mg alkylamides, and 210 mg of a proprietary synergistic extract blend containing andrographis paniculata leaf, black elderberry berries, sambucus nigra, ginger root, and zingiber officinale (see label above). Capsule excipients will include vegetable glycerin and olive oil, with the capsule containing vegetable cellulose. Placebo and echinacea capsules will be colored green and contain the same proportions of inert ingredients.