Magazine article Risk Management

Learning from Past Pandemics

Magazine article Risk Management

Learning from Past Pandemics

Article excerpt

[ILLUSTRATION OMITTED]

Pandemics are rare events. Our understanding of them comes mainly from data and information obtained from studying four events over the past 120 years: the 1889 "Russian Flu" pandemic, the 1918 "Spanish Flu," the 1957 "Asian Flu" and the 1968 "Hong Kong Flu."

One of the fundamental lessons learned from the past is that pandemics occur in waves. A pandemic wave is a fluctuation in the number of pneumonia- and influenza-related infections and deaths over a given period in a specific geographic location. The term "wave" relates to the number of infections building up, peaking and subsequently tapering off, and the duration and intensity of each wave can vary greatly from pandemic to pandemic-and even within individual pandemics. The reasons for multiple waves of varying impact are not precisely understood, but they probably include adaptation of the virus to its new host, demographic or geographic variation, seasonality and the overall immunity of the population.

Three identifiable waves characterized the Russian Flu pandemic. The waves were spread out over a period of three years with demarcated inter-pandemic periods between each wave. The first wave occurred between the spring and winter of 1889 and moved slowly but steadily throughout the world, causing high morbidity but low mortality. The second wave occurred a full year later in the spring of 1891 and caused high mortality. The third wave occurred in early 1892 and was relatively mild.

The "Spanish Flu" was even more devastating, infecting approximately 500 million people and killing at least 50 million--and possibly as many as 100 million. In the United States, the 1918 pandemic killed as many as 675,000 people, with the highest incidence of death occurring among adults under 45 years of age. The mortality rate in Europe and the United States during the 1918 pandemic was 2.5%. By comparison, mortality rates during the 1957 and 1968 pandemics were 0.02% and 0.01%, respectively.

In the case of the 1918 pandemic, three waves occurred in quick succession over a 12-month period with each wave barely separated by an inter-pandemic period. The first wave occurred in the spring and summer of 1918 with isolated outbreaks occurring unevenly throughout the United States and Europe. …

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