Prince William Health System and Inova Health System tightened their visitation policies to better protect patients, guests, and staff members from the H1N1 virus, officials from the Virginia-based organizations said. Both hospital companies are not allowing guests younger than 18 to visit. In addition, guests older than 18 who are demonstrating flulike symptoms will not be allowed into the Inova patient care units and are "urged" not to visit Prince William Health System.