The most important weapon against influenza that you can add to your herbal arsenal is elderberry extract.

Whether you are concerned with the seasonal flu or the potential of a deadly strain of influenza becoming pandemic, elderberry extract is a vital addition to your vault of flu remedies.

Unlike the highly touted flu shot, black elderberry has actually been conclusively proven to be effective. It is one of the few natural remedies that has been written up in the medical journals. The studies I’m listing here are based on black elderberry extract (Sambucus nigra L) - name brand Sambucol.

According to PubMed:
Sambucus nigra L. products – Sambucol – are based on a standardized black elderberry extract. They are natural remedies with antiviral properties, especially against different strains of influenza virus. Sambucol was shown to be effective in vitro against 10 strains of influenza virus. In a double-blind, placebo-controlled, randomized study, Sambucol reduced the duration of flu symptoms to 3-4 days.
.........................................read more)
http://www.activistpost.com/2013/01/elderberry-extract-natures-tamiflu.html