SARS was primarily a pneumonia-causing virus, and significant transmission did not readily occur until the patient was severely ill.

“SARS was a virus that really cause pneumonia not much more so the virus didn't readily spread from one person to another until that first person was pretty ill and then if that person went in the hospital and you now started as a were mucking up their lung fluids so that virus was now released into the air by a procedures either intubation or suctioning or whatever else needed to be done”