Dr. Anthony Fauci, chief medical advisor to the president and director of the National Institute of Allergy and Infectious Diseases (NIAID), warned Friday that health officials must be “very careful” not to vaccinate with the “live” oral polio vaccine, and instead use the safer “kill vaccine.” Purportedly, a man in Rockland County, N.Y., who was recently diagnosed with Polio may have been exposed to it by someone who recently received the “live” oral vaccine, officials suggest.