How Your Google Search Data Is Used To Track Coronavirus

Chris York
·2-min read

When the coronavirus pandemic began, governments around the world scrambled – with varying senses of urgency – to pull together the tools and resources needed to fight it.

While much attention has rightly been paid to vaccines, lockdowns and the merits of face masks, one powerful weapon hasn’t got much credit – your keyboard.

That’s right, Public Health England (PHE) uses Google search data – particularly searches about Covid-19 symptoms – to “understand and monitor the pandemic in England”.

And the data, which contributes to the government’s weekly surveillance reports, was able to accurately give a 20-day warning about whether cases were going up or down during the height of the pandemic.

The assumption is pretty straightforward – people with symptoms of an illness will Google what is wrong with them before they go to or even book an appointment with a health professional.

Google also has the added bonus of being relatively anonymous so people tend to be far more honest than they are when talking to other people about illnesses (and practically everything else), a phenomenon documented in the book Everybody Lies by Seth Stephens-Davidowitz.

Using a survey from March that examined the “first few hundred” cases, a list of 19 symptoms associated with confirmed Covid-19 cases was created as well as their probability of occurrence.

A separate and more general search category was created for Covid-19-related keywords, for example “Covid-19” itself and of course “coronavirus”.

Researchers then used a specialist version of the publicly available Google Trends dashboard that focuses on health data called Google Health Trends.

And the results were startling.

“When we looked at this for a number of countries, around eight, we saw on average there was a 20-day early warning that Covid cases are going to go up or down,” one of the architects of the method, data scientist Bill Lampos of University College London, told HuffPost UK.

“We expected...

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