Randomized study of the efficacy and safety of oral elderberry extract in the treatment of influenza A and B virus infections. 2004, Zakay-Rones, J Int Med Res

A small, randomized, double-blind, placebo-controlled trial of treatment of influenza with elderberry extract. The elderberry extract shortened the disease 4 days compared with placebo. [1], [2], [3], [4].
For comparison, Tamiflu shortens illness for 17 hours, promoting, with the risk of psychiatric complications and renal failure but, for some reason, the governments of all countries spend billions of dollars on the purchase of stocks of Tamiflu, and no one buys elder.