The most cost-effective way to prevent deaths from invasive pneumococcal disease is to offer the pneumonia vaccine to all Americans over the age of 50, according to a new study in the Annals of Internal Medicine. Although the vaccine is recommended for all seniors over the age of 65, only about half of them received the immunization in 2001, says lead author Dr. Jane E. Sisk of the Mount Sinai School of Medicine. The study found that vaccinating individuals between the ages of 50 and 64 would lower overall health care costs, and it said that offering the vaccine to everyone 50 years of age or older would be more cost-effective in preventing deaths than some other preventative measures, such as screening for colon cancer.