Influenza in Seniors – How Deadly Is It? Flu shots for senior citizens may be less beneficial than previously suggested, according to recent studies. Older patients have long been susceptible to dying from flu complications, such as pneumonia and fever. Earlier research had stated that influenza vaccinations reduce the risk of mortality among the elderly by 50 percent. But new data models showing that the flu causes only 5-10 percent of winter deaths in seniors have raised questions about the accuracy of previous findings. And because the immune system works at a reduced capacity in the elderly, the vaccine may be less than 30 percent effective for them. Still, even skeptical scientists say that seniors should continue to get vaccinated.