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Fact-check: Do pandemics occur every 100 years?

Published on Fri 03 Mar 2023 at 10:05

Several past pandemics that occurred without such synchrony have gone unnoticed by social media posts making these inaccurate claims.

By Toibah Kirmani

According to some social media posts on Facebook and Instagram, pandemics occur once every 100 years. They cite the Great Plague of Marseille (1720), the Cholera outbreak (1820), the Spanish flu (1920), and the coronavirus pandemic (2020) as evidence to support their claim.

However, there is no scientific basis to the reasoning. Even though it may look like there is a pandemic pattern, the claim is not factually accurate:

  • The Great Plague of Marseille wasn’t a pandemic. The outbreak was confined to France. As defined by the World Health Organization, a pandemic is “the global spread of a new illness”.

  • Three of the other cases did not occur in the years specified. The cholera epidemic started in 1817, not 1820, while the Spanish flu pandemic started in 1918, not 1920. COVID began in December 2019, not 2020.

  • More importantly, several past pandemics that occurred without such synchrony have gone unnoticed by these social media posts. Like the AIDS pandemic that began in the 1980s, the Asian Flu of 1958, the Hong Kong Flu of 1969, SARS in 2003, Swine Flu in 2009, and MERS in 2012, to name some.

First Check member and science communicator, Dr Rohini Karandikar reasons that COVID’s occurrence nearly 100 years after the influenza pandemic is just a coincidence. “Experts have warned that excessive destruction of forests might expose humans more to animals, increasing the risk of animal viruses infecting humans and causing more epidemics in the future. An epidemic can cause another pandemic due to human behaviour (not masking or not taking control measures) or the infectious agent’s ability to escape the immune system and become resistant to available drugs,” she explicates.

Several factors determine if an epidemic will become a pandemic. “This includes how fast the causative agent spreads, what control measures governments and health officials take, available medicines, etc. Additionally, causative agents such as some viruses mutate rapidly, forming new variants. These variants can become more infective, increasing the chances of an epidemic becoming a pandemic,” she further notes.

In other words, pandemics don’t follow a calendar. The next pandemic could occur within the next decade, or even earlier.