The American health care worker being treated for Ebola virus disease at the National Institutes of Health Clinical Center in Bethesda, MD, has improved from critical to serious condition, NIH announced today. Admitted March 13, the patient tested positive for the disease while volunteering in an Ebola treatment unit in Sierra Leone. The hospital has a special high-level isolation unit staffed by infectious disease and critical care specialists. For more on Ebola and preparedness resources for U.S. hospitals and health care workers, visit www.cdc.gov/vhf/ebola/healthcare-us and www.aha.org/ebola.