Keir Starmer ridiculed the prime minister for denying the UK had been left in the slow lane – after his plans for an app were abandoned – telling him Berlin’s was in operation on 15 June.
“Other countries are ahead of us. When are we going to have a working app?” the Labour leader demanded to know.
Sharing the full story, not just the headlines
Mr Johnson provoked astonishment on Tuesday when he claimed no other country had stolen a march with the technology.
In fact, France, Australia, Singapore and Latvia are among other countries that have launched app, although uptake has been fairly low in some of those countries.
The prime minister is under pressure after the embarrassment of ditching plans for a custom-made NHS app – after £12m was spent on it – because of technical problems.
Put on the spot, Mr Johnson claimed the app had only ever been imagined as “the icing on the cake”, although health secretary Matt Hancock repeatedly argued it was essential to preventing infection spikes.
And, despite apps being used in numerous countries, he insisted: “If we can get it to work it’ll be a fine thing, but there isn’t one anywhere in the world so far.”
The two leaders also clashed over the physical track-and-trace system, Sir Keir claiming two-thirds of Covid-19 cases were not being successfully contacted.
The latest news on Brexit, politics and beyond direct to your inbox
Register with your social account or click here to log in
“The prime minister risks making the mistakes he made at the beginning of the pandemic, brushing aside challenge, dashing forward, not estimating properly the risks,” he warned.
“If two-thirds of those with Covid-19 are not being contacted that is a big problem, because if we don’t get track, trace and isolate properly running we can’t open the economy, we can’t prevent infection spreading.”
He added: “What is the government’s strategy for closing the gap between the number of people with Covid-19 and those going into the system, not what happens to those that go into the system?”
But Mr Johnson replied: “The 33,000 cases in the country is, of course, an estimate.
“What NHS test and-trace is doing is contacting the vast majority of those who test positive and their own contacts and getting them to self-isolate, and it is a formidable achievement.”