“Compounds from elderberries can directly inhibit the virus’s entry and replication in human cells, and can help strengthen a person’s immune response to the virus.”
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Paper: https://www.sciencedirect.com/science/article/abs/pii/S1756464619300313?via%3Dihub
Golnoosh Torabian, Peter Valtchev, Qayyum Adil, Fariba Dehghani. Anti-influenza activity of elderberry (Sambucus nigra). Journal of Functional Foods, 2019; 54: 353 DOI: 10.1016/j.jff.2019.01.031