CNN Chief Medical Correspondent Dr. Sanjay Gupta writes about how a highly lethal pandemic flu would differ from the normal seasonal flu viruses, noting it would likely affect every human on Earth. He comments that pandemic flu is apolitical and does not discriminate between rich and poor. Geographical boundaries are also meaningless, and it could circle the globe within hours. The Spanish Flu of 1918 was an example of a flu pandemic, which is estimated to have caused illnesses in 20 to 40% of the world’s population and resulted in more than 50 million deaths. With pandemic flu, Dr. Gupta notes that we cannot rely solely on the body’s ability to fight; a vaccine is the only real hope. But the current timeline for developing and deploying vaccines would mean up to 20 million might die before they could be immunized. However, if the timelines could be moved up by a matter of weeks, that number could be reduced one hundred-fold. CNN.