Remember the H1N1 strain of influenza? Science Life's Rob Mitchum offers a fascinating look at the H1N1 influenza pandemic in 1918 and why, he says, the world dodged a bullet with the 2009 pandemic:
So what saved us from a re-run of 1918? The scientific jury is still out, though a number of factors have been proposed by scientists. Older people may have been exposed to similar viruses in their youth, offering partial immunity; a Finnish study found that 96% of people born between 1909 and 1919 had antibodies against the 2009 H1N1 virus. Advances in disease surveillance, antiviral medication, public health measures and vaccination may have softened the blow, David said, but vaccination rates among children for H1N1 were distressingly poor in 2009: only 30 percent. Given that schoolchildren were determined to be "the engine driving the fall '09 wave," that's a worrisome figure in case the next pandemic is more 1918 than 2009.
The entire entry is worth a read. Also of interest is an account of the 1918 epidemic from the Journal of the American Medical Association (subscription required; .pdf):
The incubation period varied from a few hours to one or two days. Shortly after the arrival of the first fifty soldiers, five of the nurses in attendance on these patients became violently ill, and during the following two weeks more than fifty nurses and twelve of the resident physicians contracted the disease. Three of the nurses died. Blood cultures, nasopharyngeal and tonsil swabs and cultures of the washed bronchial secretion were immediately taken by the laboratory staff, and four of the laboratory assistants were suddenly taken ill within the next forty-eight hours.