Influenza is a common and extremely contagious respiratory illness caused by the influenza virus. According to the Centers for Disease Control and Prevention, up to 20% of the United States population contract influenza annually, while more than 200,000 people are hospitalized for flu-related symptoms, and up to 36,000 people die annually from the illness in the United States. Influenza spreads around the world in seasonal epidemics, and may often lead to flu pandemics, like those experienced in recent years.

There have been numerous studies on the effect that blackcurrant anthocyanins have on virus activity, and proven anti-influenza virus effects of were shown, including inactivation of A and B viruses, inhibition of viral attachment to cells (98%), and complete suppression of virus growth in cells.
In one study, experiments were conducted on the function of blackcurrant juice to inhibit viral attachments. The results of the study demonstrated that just 2% blackcurrant juice was able to prevent infection from 99% or more of the viruses that would otherwise have infected the cells.

Black currant health benefits against influenza