The study, run by CMU Delphi Research, will ask health-related questions via a survey link at the top of some US Facebook users’ news feeds.

Findings will be used to inform CMU’s pandemic forecasting and to produce heat maps of self-reported symptoms. The social network said in a blogpost: "CMU Delphi Research won’t share individual survey responses with Facebook, and Facebook won’t share information about who you are with the researchers."

Facebook is also launching new categories of its existing Disease Prevention Maps, which aggregate mobility data from Facebook to be used by health researchers. 

The new datasets are: co-location maps, which show the probability of people coming into contact with others in a different area, movement range trends showing movement at a regional level, and a ‘social connectedness index’ showing friendships across US states and counties.

In the past few weeks, various technology companies have begun initiatives aimed at tracking the spread of Covid-19, including a joint contact-tracing technology launched by Apple and Google.

However, campaigners and researchers have warned of risks to privacy, saying that increased surveillance could be difficult to scale back once the pandemic is over.