Germany and Ireland have both trumpeted their success in rolling out contact-tracing apps.
But is there any evidence that they are doing what they are designed to do – warning people they could be infected with the virus?
Not yet – and the privacy-conscious way in which they are designed could mean we will never know how effective they have been.
Last month, the UK government announced that it was abandoning a centralised NHS contact-tracing app for England and switching to a decentralised version, based on the Apple-Google toolkit. This model has been favoured by privacy campaigners because the matching process takes place on users’ smartphones rather on a central computer, providing a greater degree of anonymity.
But the government stressed that the new version would