President Obama tours a lab at the Vaccine Research Center at the National Institutes of Health

President Barack Obama, Health and Human Services Secretary Sylvia Mathews Burwell and Dr. Anthony Fauci, Director, National Institute of Allergy and Infectious Diseases, tour a lab at the Vaccine Research Center at the National Institutes of Health in Bethesda, Maryland, Dec. 2, 2014. Dr. Nancy Sullivan, Senior Investigator, Chief Biodefense Research Section explains the labs investigational Ebola vaccine candidate currently being tested on humans.