To the Editor: The Naval Health Research Center serves as the Navy hub for the Department of Defense's Global Emerging Infections Surveillance and Response System (GEIS), in which it monitors influenza-like illness among recruit trainees of all military services, military dependents, and crew members of large Navy ships (population, >1000). The center works in collaboration with the Border Infectious Disease Surveillance Project of the Centers for Disease Control and Prevention (CDC), which monitors populations located on the border between California and Mexico. The first two human cases of novel swine-origin influenza A (H1N1) virus (S-OIV), known as swine flu, in...