The real-world effects of ‘fake news’ – and how to quantify them

August 9, 2020

Readers will be aware that social media networks are rife with conspiracy theories and misinformation about the origins of the COVID-19 virus and treatments for the disease. Misinformation is not a new phenomenon. However, the rise of social media and changes in how people obtain and consume news, have made misinformation much more infectious: fake news can now spread faster, wider and more freely than ever before. This so-called ‘infodemic’ is having significant – and in the current crisis, even dangerous – effects on public health. Outside of public health, concerted smear campaigns can cause permanent damage to individual and corporate reputations.   

In this article, we explore these important issues using a recent ‘test case’: misinformation around the Measles, Mumps and Rubella (MMR) vaccine. We identify and measure misinformation on Twitter, quantify the causal effect it has in the real-world, and identify what implications their findings have for legal and policy responses more generally – including in relation to the regulation and behaviour of social media companies, and to the determination of commercial disputes. 


Misinformation is not a new phenomenon – especially when it comes to infectious disease, vaccination and public health. The roots of the anti-vaccination movement can be traced back to the 18th Century, when smallpox inoculations were outlawed after being blamed for a severe outbreak of the disease in Paris.1

Thankfully, vaccination techniques have since improved, and the public health case for widespread vaccination has become stronger, better understood and more widely accepted, resulting in global vaccination programmes and the effective eradication of certain infectious diseases. 

However, the anti-vaccination movement persists and it is known to have a significant effect on public health. In 1998, for example, Dr Andrew Wakefield authored a study published in The Lancet, a well-regarded medical journal, claiming to identify a link between the Measles, Mumps and Rubella (MMR) vaccine and the onset of symptoms of autism. The Wakefield study was eventually debunked, found to be fraudulent and revoked entirely – but the damage was done. The study received widespread publicity at the time and was blamed for contributing to a sharp fall in MMR vaccination coverage rates and a resurgence of the disease in Western countries.2


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