MEPs have been debating the future of COVID-19 tracking apps on smartphones that are aimed at getting a grip on the disease's spread.
The apps use Bluetooth technology to give authorities an idea who an infected person has come into contact with.
Other versions, that use GPS tracking, have proved to be more controversial.
Some countries like Austria have launched an app, while others, such as France, have yet to launch one over privacy concerns. The UK, meanwhile, is testing its version on the Isle of Wight, off the south coast of England.
Spanish MEP Juan Fernando López Aguilar, chairman of the European Parliament's civil liberties committee, said app data must be anonymous.
“If member states are to share their knowledge of the patterns of the spread of the pandemic, according to these tracing apps, that data should be anonymised," he said.
"Because by no means data related to the health, the individual health of European citizens is to be shared without their consent. That’s completely forbidden."
Experts, meanwhile, are keen to ensure the apps work across borders so that they are effective when widespread travel within the EU returns.
“It shouldn’t really be a border issue in practice, it should be an issue of whether apps are interoperable, rather than whether or not you’re near a border," said EU tech expert Jennifer Baker. "Because it’s not based on the geolocation, it’s based on Bluetooth proximity.
"So if I had a German friend who flew into Belgium with their German app, it’s not really about whether they’re near a border, it’s about whether their app is compatible with the apps people around them are using."
Apple and Android are opening up their back end coding so app makers can ensure that the different apps are compatible with one another.