Flu is something we deal with every year. In the U.S., that unfortunate time is usually between October and May. Thanks to vaccines and resistances, influenza generally means an agonizing week or so to anyone unlucky enough to catch it. The virus becomes particularly deadly when a new strain emerges for which there is no established resistance. Outbreaks of new strains can quickly turn from an epidemic (spreading beyond a local population) to a pandemic (reaching worldwide proportions).
The five worst influenza pandemics all occurred within the last 100 years. Some experts estimate influenza has killed more people in that time than the Black Death (bubonic plague), which took 200 years to run its course.
Continue on to read about the five worst flu pandemics.
The 2009 Flu Pandemic
2009 – 2010
18,000 to 300,000 deaths
Origin of the disease, also known as Swine Flu, is not known, but most likely circulated amongst humans for months before being recognized as a novel strain. Uncharacteristic of most flu strains, this disease did not disproportionately infect adults over the age of 60. Fatalities confirmed by laboratory testing number around 18,000. Experts agree unconfirmed or unreported deaths could be as high as 300,000, with the World Health Organization saying the number could be even higher.
A crowd of people wait in line outside a clinic set up for Swine Flu inoculations, Nov. 2, 2009, in Worcester, Mass. (AP Photo/Steven Senne)
The Hong Kong Flu
1968 – 1969
1 million deaths
The Hong Kong Flu had a lower death rate than previous pandemics. It’s thought that a resistance built up from the previous pandemic, availability of antibiotics and limited exposure during the winter holidays helped slow the spread and keep the mortality rate low.
Experts say this pandemic could have been much worse had it not been for increased access to antibiotics and resistance to the flu virus. (AP Photo/Toby Talbot)
The Asian Flu
1957 – 1958