Elderberry: There are two main species of elder - European and North American
European Elderberry Sambucus nigra L:
North American Elderberry Sambucus canadensis
Both plants have very similar constituencies and beneficial for viral cold and flu support. The North American version has adapted to the North American climate and has a few more constituencies that ensure plant survival on this continent.
Sambucus nigra has been used historically all over the world for centuries. Described by ancient physicians as far back as the fifth century BCE as the country people’s medicine cabinet ("The Clinical Guide to Elderberry", 2018), elderberry has been relied on for cold and flu like illness, with the accompanying nasal congestion, cough, and fever throughout all of the life stages including pregnancy, lactation, and childhood. Elder has been specifcally shown to reduce hemagglutination and replication of four strains of influenza A and three strains of influenza B in vitro ("The Clinical Guide to Elderberry", 2018). Though there is a general recommendation to avoid elders use during these life stages and consumed safely for ages and revolves more around the medical reluctance to recommend substances not studied extensively allopathically ("The Clinical Guide to Elderberry", 2018). As herbal medicine in general has gained more acceptance this is becoming a thing of the past with an increasing number of herbs, including elder. In the case of Sambucus nigra scientific evidence is growing in its efficacy as an antiviral remedy for Influenza A and B as well as several bacterium and fungal infections.
A well designed laboratory-based study analyzing the antibacterial and antifungal capability of nine botanicals to include elder flowers and berries. Each plant was then evaluated for its effectiveness within three different solutions, ethanol, and water. The botanical solutions were then compared in minimal inhibitory concentrations against vancomycin, amoxicillin, and amphotericin B (Cioch et al., 2017). Though this study had nothing to do with viral infections, it was highly intriguing, especially when it came to the statistical differences regarding botanical efficacy in relation to carrier agent. It was also interesting to note the differences in the same plant's different anatomical parts (i.e. elder flowers versus berries) has a direct impact on the microorganisms affected. The antimicrobial capability of elder is attributed to the flavonons, flavonols, and dihydroflavonols of the flower. Both flower and fruit was found to inhibit both gram-negative (Salmonella poona and Pseudomonas aeruginosa) and gram-positive bacteria Staphylococcus aureaus, Bacillius cereus). Though the overall conclusion of the study was that of the plants tested there was relatively low levels of activity against the microorganisms used but recommended further study as to how to increase the efficiency of inhibition that was observed (Cioch et al., 2017).
For more information I recommend
Cioch, M., Satora, P., Skotniczny, M., Semik-Szczurak, D., & Tarko, T. (2017). Characterisation of Antimicrobial Properties of Extracts of Selected Medicinal Plants. Polish Journal Of Microbiology, 66(4), 463-472. https://doi.org/10.5604/01.3001.0010.7002
The Clinical Guide to Elderberry. (2018). Retrieved from http://cms.herbalgram.org/press/files/elderberry-scr.pd
The Journal of the American Botanical Council - Elderberry. (2004). Retrieved from http://cms.herbalgram.org/press/files/elderberry-scr.pdf
Harnett, J., Oakes, K., Carè, J., Leach, M., Brown, D., & Cramer, H. et al. (2020). The effects of Sambucus nigra berry on acute respiratory viral infections: A rapid review of clinical studies. Advances In Integrative Medicine, 7(4), 240-246. https://doi.org/10.1016/j.aimed.2020.08.001