Google has published graphs showing how COVID-19 has brought countries like Italy and Spain to a standstill, led to runs on shops and emptied places of work. 

The analysis of location data from billions of Google users' phones is the largest public dataset available, which – although anonymized – can be used to help health authorities assess if populations are abiding social restrictions issued across the world to rein in the virus.

The company released reports for 131 countries with charts that compare traffic from 16 February to 29 March. The graphs show steep declines in retail and recreational activity, with reduced numbers at train and bus stations, grocery stores and workplaces compared with a five-week period earlier this year.

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Google said it published the reports to avoid any confusion about what it was providing to authorities, given the global debate about balancing privacy-invasive location tracking with the need to prevent further outbreaks.

The data often correlated with the severity of outbreaks and the breadth of orders imposed by governments.

Italy and Spain, two of the hardest-hit countries, both had visits to retail and recreation locations such as restaurants and movie theaters plunge 94 percent. The United Kingdom, France and Philippines had declines of more than 80 percent while India, which went into a sudden 21-day lockdown on March 25, was also notable at 77 percent.

In the United States, where restrictions have varied greatly state to state, and in Australia, where good weather initially prompted many people to go to the beach before social distancing measures were ratcheted up, the drops were less steep at under 50 percent.

In contrast, in Japan and Sweden, where authorities have not imposed harsh restrictions, visits to retail and recreation sites fell by roughly only a quarter – while in South Korea, which has successfully contained a large outbreak through aggressive testing and contact tracing, the decline was just 19 percent.

The data also underscores some challenges authorities have faced in keeping people apart. Grocery store visits surged in Singapore, the UK and elsewhere as travel restrictions were set to go into place. Visits to parks spiked in late-March in Germany, prompting politicians to threaten a curfew. 

Data in Google's reports come from users who enabled Google's "location history" feature on their devices. The company said it adopted technical measures to ensure that no individual could be identified through the new reports.

"These reports have been developed to be helpful while adhering to our stringent privacy protocols and policies," wrote Karen DeSalvo, chief health officer for Google Health and Jen Fitzpatrick, senior vice president for Google Geo in a blog post.

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China, Singapore, South Korea and other countries have asked residents to use apps and other technology to track their compliance with quarantines, while it is under consideration in Germany, a country with strict privacy laws. 

Data privacy activists argue the apps and the information they collect can impinge upon individual liberties. 

Infectious disease specialists have said analysing travel across groups by age, income and other demographics could help shape public service announcements.

Google, which infers demographics from users' internet use as well as some data given when signing up to Google services, said it was not reporting demographic information. However, the company said it was open to including additional information and countries in follow-up reports.

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