H1N1 1918:
a) one of the most deadly pandemics in world history
b) unusually severe and deadly strain of avian influenza that killed some 50 to 100 million people worldwide over about a year in 1918 and 1920
c) especially deadly because it elicited a cytokine storm the lungs leading to overstimulation of the immune system via release of cytokines
d) cytokine storm lead to extensive leukocyte migration towards the lungs, causing lung tissue to secrete liquid into thelungs