The 13-valent pneumococcal conjugate vaccine (13vPnC) is being developed for adults to prevent pneumococcal diseases such as meningitis (inflammation of the brain lining), septicemia (blood poisoning), and pneumonia (inflammation of the lungs). As trivalent influenza vaccine (TIV) is frequently given to adults, it is important to show that both vaccines can safely be given together without affecting the immune response (body's ability to protect against disease).