Today getting a flu shot during flu season is routine, but the world didn’t always have vaccines. Millions of people died during various pandemics throughout history as various flu strains circled the planet.
Limited information and data exist about how flu spread before the 1800s, as doctors and scientists kept spotty records, if they kept them at all. However, there are a few periods in written history that point to pandemics spreading around the world at fairly regular intervals. In 412 B.C. Hippocrates described flu-like symptoms in patients in Greece. In the late 1400s, a mysterious “sweating sickness” began spreading across Europe, killing the mayor of London and later reappearing in epidemics through the mid 1550s. Later, in 1580, the first official recorded flu-like pandemic started in Asia and spread to Africa and most of Europe. It’s not known exactly how many people died, but the death toll was devastating.
Click through the gallery to see how other pandemics affected global health.
Photo illustrations: Courtney Niemann
1889: Russian Flu
It took just four months for this flu to spread across Europe, reach the United States and circle the globe. Many believe the pandemic, which eventually killed one million people, spread so quickly thanks to extremely dense rail lines across the continent. In fact, it was the first pandemic since the lines had been laid down (though there were five smaller pandemics that came before it during the 1800s). The Russian Czar himself contracted the flu and recovered. This was also the first time that scientists and doctors began making detailed records of a pandemic and how it spread.
1918: Spanish Flu
Considered one of the deadliest pandemics of all time, the Spanish Flu eventually infected 20 to 40 percent of the entire world’s population. It’s estimated that 50 million people died in total (World War I, in comparison, claimed about 16 million lives), though that number is disputed and differs significantly depending on the source.
The strain of flu was so virulent that many healthy adults who caught it in the morning were dead by dusk. It’s still not known why those 20- to 50-year-olds had the highest mortality rates, since those typically most susceptible to influenza are children, the elderly and those with weakened immune systems. After just one year the flu had claimed enough lives in the U.S. (an estimated 675,000) to cause the country’s average life expectancy to drop by 12 years.
1957: Asian Flu
This pandemic was predicted before it began—health officials recognized early on that there was little immunity in people under age 65, and that a worldwide spread was highly likely. The flu first appeared in a southwestern province of China and traveled around the world in two waves.
While scientists were hard at work making a vaccine, the first wave of flu hit the U.S. in a series of small outbreaks during the summer. Once school began the disease spread rapidly as children became the main carriers, passing it among each other and eventually bringing it home to their families.
Research at the time found that school closings greatly reduced the number of infections. By August 1957 a small amount of vaccine was made available and flu rates worldwide seemed to dissipate. But in January and February 1958 the world saw a second spike of infections with a second wave of Asian flu that led to many deaths. All told, the flu claimed about two million lives worldwide, about 69,000 of which were in the US.
1968: Hong Kong Flu
This 1968 pandemic originated in Hong Kong but wasn’t nearly as severe as the 1957 Asian flu. It’s believed that many people had gained immunity during the previous pandemic, ultimately saving their lives. Another possibility for the reduced impact of the disease was that it peaked in December, right around the time that children were out of school for the holidays.
Additionally, it only took scientists and government officials one month to develop and distribute a vaccine. Despite the fact that it was the mildest pandemic of the 20th century (though pandemics that came after would be milder), it managed to cause one million deaths worldwide and killed about 34,000 people in the US.
1976: Swine Flu
The earliest swine flu outbreak was a worldwide pandemic scare that never became an actual pandemic. The virus that infected somewhere between 13 and 500 people (reports vary) in Fort Dix, New Jersey was called H1N1 (which you may remember from the world's most recent swine flu outbreak—H1N1 was the most common cause of flu in 2009).
Scientists incorrectly identified the virus as a version of the Spanish Flu strain from 1918, deemed it the “killer flu” and said it could become more deadly than the pandemic that infected nearly 40 percent of the world. Panic ensued. The president and Congress passed a mass-immunization law, earmarking $135 million for a swine flu program to inoculate the country.
Over the course of three months some 40 million Americans were vaccinated, but the disease never managed to appear outside of the Fort Dix area, where one person died. Many believed the virus emerging there could have been an anomaly, passed between an infected animal and a member of the military base. But it wasn’t strong enough to spread beyond the close quarters of the barracks.
Nonetheless, pandemics have really never been the same. Whether it's due to regular inoculation programs or improved healthcare around the world, pandemics are becoming less severe with every trip around the world.