by the appearance of influenza type H2N2, which replaced the H1N1 strain that circulated previously. This figure also illustrates that although influenza A is the most serious cause of mortality in the elderly among the influenza viruses, in some years influenza B is more of a problem than influenza A.
Although the very young and the elderly are normally at the most risk from influenza, the influenza pandemic of 1918-1919 was unusual in that mortality was high in healthy young adults. The age distributions of people dying of influenza and the related pneumonia are compared for the years 1917 and 1918 in Fig. 4.17. The much higher death rates in the young and the elderly in 1917, the normal pattern, is apparent. The dramatic increase in the death rate in the 20- to 29-year-old group in 1918, in which people of this age were more likely to die than the old and the young, is striking. The epidemic caused by this extremely virulent virus spread around the world over a period of about a year and ultimately infected an estimated 20% of the world's population. The overall mortality was perhaps 2% but in some
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SWINE INFLUENZA frightening you? CONCERNED about the health implications? Coughs and Sneezes Spread Diseases! Stop The Swine Flu from Spreading. Follow the advice to keep your family and friends safe from this virus and not become another victim. These simple cost free guidelines will help you to protect yourself from the swine flu.