The utility of elderberries is definitely not proven, at least as far as bird flu is concerned. If bird flu starts going human to human, I'll stick with the herbs that do not activate the cytokine storm for sure.
There is significant misinformation floating around here. Sambucol - a patented Elderberry extract developed by a well-known Israeli Virologist - is indeed proven effective in numerous double-blind well-sampled scientific studies in significantly reducing common flu symptoms. The Israeli Army uses Sambucol both as a flu preventative and duration shortener.
No, Sambucol is not proven in fighting H5N1 virus in humans, but early reports on animal tissue look extremely promising. Sambucol is indeed one of nature's most effective viral remedies, and is now among the world's best selling herbal/natural drugs.
Another wonder drug of nature, which effectively fights both viral and bacterial illness is Olive Leaf Extract. But some OLE's are much more effective than others, for reasons I won't get into here. East Park and Ameriden are two of the best OLE extractors, both having effective and patented processes.
I am an engineer and not affiliated with any of these companies in any way - though I've been a regular user of Sambucol and OLE for years and simply don't get sick any more. I've found that keeping a low-calorie alkaline diet (no sugars, etc.) is another effective tool in maintaining optimal health.