An image shared on Facebook more than 500 times claims a pandemic occurs exactly every 100 years.

Verdict: False

The image misstates the timeline for three of the four disease outbreaks, and one cannot be considered a pandemic. Other pandemics have occurred more frequently than every 100 years.

Fact Check:

Some social media users have spread a conspiracy theory on Facebook that suggests pandemics have occurred exactly every 100 years since the 1700s, linking the Great Plague of Marseille to 1720, the cholera outbreak to 1820, the Spanish flu to 1920 and the new coronavirus to 2020.

The World Health Organization defines a pandemic as “the worldwide spread of a new disease.” The Centers for Disease Control and Prevention (CDC) offers a similar definition. (RELATED: Does Every Election Year Coincide With A Disease Outbreak?)

But the dates in the image for when these disease outbreaks began, with the exception of one, are inaccurate, and numerous pandemics have occurred outside the 100-year interval the post suggests.

The year listed for the Great Plague of Marseille, which killed as many as 126,000 people from 1720 to 1722, is correct, according to Britannica. However, that outbreak was largely limited to France, meaning it doesn’t fit the widely-accepted definition of a pandemic.

The first cholera pandemic started in 1817, three years before the date listed in the Facebook post. That pandemic started in India and had spread to the Middle East, Southeast Asia and parts of the Mediterranean by the time it ended in 1823, according to the U.S. National Library of Medicine. Four other major cholera pandemics occurred during that century as well: 1848-1850, 1854-1857, 1865-1867, and 1873-1874.

The post claims the 1918 influenza pandemic, commonly known as the Spanish flu, took place in 1920, but that year doesn’t hold up. The Spanish flu pandemic actually started in 1918, per the CDC website. Over the roughly one year it lasted, the Spanish flu infected around 500 million people and killed some 50 million others worldwide.

The new coronavirus was declared a pandemic by the WHO in March 2020, but the virus first emerged in the Chinese city of Wuhan in late 2019, according to The New York Times. At the time of publication, the new coronavirus virus has infected some 3.5 million people worldwide, per the Johns Hopkins Coronavirus Resource Center.

From 2009 to 2010, the H1N1 flu pandemic, commonly known as swine flu, killed between 151,700 and 575,400 people globally, according to the CDC. That puts just 10 years between it and the ongoing coronavirus pandemic, further disproving the claim.

The post ignores other pandemics that happened between 1720 and the present day, including:

• The Third Plague Pandemic (1855): killed around 12 million globally
• The “Asian Flu” pandemic (1957-1958): killed 1.1 million people globally.
• The H3N2 Flu pandemic (1968): killed 1 million people globally

Many pandemics have occurred outside the neat 100-year pattern suggested in the Facebook post, and those that happen roughly 100 years apart are merely a coincidence. We rate this claim false.