QUOTE : Back in the disastrous flu pandemic of 1918 that killed upward of one hundred million people, there were stories of asymptomatic people getting on the subway in Brooklyn and being dead from viral pneumonia by the time they got to Manhattan. Whether such stories were apocryphal or not no one knows for sure, but I think they were true because of the virulence of that particular flu strain. What is believed now is that they died from their own immune systems going wild in what is called a cytokine storm.