On the Centenary of the Spanish Flu: Being Prepared for the Next Pandemic.

Abstract

Influenza is one of the oldest infectious diseases affecting humans. Every influenza pandemic in history has ended with disastrous outcomes regarding public health and the social economy. This year marks the 100th anniversary of the Spanish flu (H1N1) outbreak of 1918, which is recognized as the most lethal natural event in recent history. In spite of limited travel and transportation at that time, the Spanish flu pandemic of 1918 reached peak activity on multiple continents simultaneously within several months after its emergence in late 1917 from different hypothesized origins, such as US military camps, the state of Kansas, or the troop staging and hospital camp in Extaples, France ( Patterson and Pyle 1991 ; Oxford et al. 2005 ; Shanks 2016 ). However, in some islands of the Pacific region, such as in New Caledonia, the pandemic's lethal effects lasted for over 3 years, until July 1921 ( Shanks et al. 2018 ). The pandemic flu is estimated to have infected more than 500 million people, causing between 50 and 100 million deaths globally ( Patterson and Pyle 1991 ; Guan et al. 2010 ). The evidence suggests that most pandemicrelated deaths were not caused by the direct pathological effects of the influenza virus, but rather by the lethal effects of secondary bacterial pneumonia ( Chien et al. 2009 ).