In the U.S., 1 in every 20 individuals age 85 and older will have a new episode of community-acquired pneumonia each year.
Jackson M, Neuzil K, Thompson W, Shay D, et al. The Burden of Community-Acquired Pneumonia in Seniors: Results of a population-based study. Clin Infect Dis. 2004; 39(11): 1642-50. http://cid.oxfordjournals.org/content/39/11/1642.long