through electron microscopes, would that actually than normal for the elderly. The common have empowered them to halt the ? explanation is that this strain of was so There was no cure for the then, or now. new that it startled its victims' immune systems Vaccines? Another generation would pass before into overreaction, and the more vigorous the even partially effective vaccines against victim, the greater and deadlier the overreaction. influenza were developed. Even if all the The defensive swelling of membranes and knowledge and technology to produce flu increased secretion of fluids of the respiratory vaccine had been at hand in 1918, would it have system went to extremes in young adults, filling been possible to produce it in sufficient quantity their lungs with liquid until they drowned. and to distribute it across oceans and continents Overstimulation of the is a in time to stop the swiftly spreading breath- plausible theory, but we could subject it to borne pandemic? Even today, when similar rigorous testing only if something like the 19 18 questions are asked each time a new returned. strain of the virus appears, the answer falls short of This distinctive influenza swept over being a confident "yes.” the world in three major waves during 1918 and 1919. We cannot be sure where and when the The influenza of the 1900s is still something of an initial wave in the spring of 1918 started, but the enigma, but the influenza that was sweeping around earliest scientific and statistical evidence points the world at the time of the Armistice ending to the in . It attracted World I remains profoundly so. It killed tens very little attention because pneumonic of millions, usually by opening the way for complications were rare and deaths even rarer. secondary bacterial , such as those of Initially, the flu seemed no more than just another Pfeiffer's bacillus. Today, we presume that such respiratory disease of the kind that so often infections can be controlled with . But a circulates at that time of year. Only later did the significant fraction of those who died in the statisticians notice that an unusually large pandemic of 1918-19 did not live long enough after proportion of the relatively few victims of the the onset of illness to contract a secondary spring of 1918 had been young adults. . They turned slate blue in a couple of days and died of viral . Even more disturbing THE FIRST WAVE was the fact that the was especially The first wave that spread across North America dangerous to young adults for reasons that have in March and April temporarily disrupted the been plausibly, but never definitely, explained. operation of some military camps and a few factories and then disappeared. However, as it Although influenza did not significantly affect waned in North America, it rose to greater mortality in the United States until September heights in the Old World than had been 1918, its impact was so tremendous during the fall experienced at any time since the previous and early winter of that year that it skewed the influenza of 1889 and 1890. distribution of age-specific deaths into According to the record (by no means as unprecedented proportions. Ever since the U.S. complete in 1918 as today), the disease in Office of Vital Statistics started publishing first reached epidemic proportions in April in statistics on the age incidence of influenza deaths, . It swept across Europe in the spring and the distribution has been high at the extremes of summer, attacking troops indiscriminately on infancy and old age and very low in between. In both sides and interfering with military 1918, however, age-specific death rates were high operations. (General Erich von Ludendorff for the very young, higher yet for 20-to-40-year- blamed the flu, among other factors, for the olds, and lower

4 The Spanish Flu and Its Legacy