Influenza, known as the flu, is a specific viral infection of the respiratory tract, and it’s one of the common causes of pneumonia. Unlike pneumococcal diseases, the flu cannot be treated by antibiotics.“Influenza works hand-in-glove with pneumonia,” said William Schaffner, M.D., a professor of infectious diseases at the Vanderbilt University Medical Center. Schaffner added that flu shots can help prevent pneumonia.