What is Immune Booster with Echinacea with Elderberry & Zinc? Kick your immunity into high gear! With cold and flu season lasting longer each year, we’ve developed this enhanced formula to help boost your immune system. This powerful formula uses Zinc and Elderberry for a double dose of enhanced immune function. The addition of Echinacea, a traditional herb that’s been used for centuries, helps activate and encourage the body’s natural immune potential.