The UK government's new contact tracing app has been launched in England and Wales four months after its original release date.

The app will alert users who have spent time within two meters of someone infected with COVID-19, and also allows people to log their symptoms and book a test. It may also recommend someone to self-isolate and then provide a daily counter for the 14-day period.

When entering a pub, restaurant or shop, people will be required to check-in by scanning an official NHS QR code. If they later contract the virus the venue will be alerted.

The new app has been trialed in the east London district of Newham and on the Isle of Wight. It's the second time the government has trialed an app. The first one had technical problems, but the government insists this one is now ready for a national roll out.

Noor Abidin's Malaysian restaurant in Westfield shopping centre has been taking part in the app trial, but she says the main problem was that very few customers had downloaded it.

"I suggest the government be more proactive," she told CGTN. "We can do our bit in posting the NHS QR code, but you have to get through to people to use it."

Many pubs and restaurants have already been using their own QR codes to track customers.

Rob Claassen, of the Salisbury pub in London's Queen's Park, says: "The most important thing is that if we have any local transmission in the pub we need to have the ability to contact anyone who has been there on that evening to prevent the transmission of COVID-19."

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UK health secretary Matt Hancock has noted that "The app can find contacts that human contact tracers can't – for example if you're sitting near them on public transport."

The UK's track, trace and test system has been described by critics as a "shambles." Over the last couple of weeks, testing centers have been overwhelmed with people and the government has admitted it will take months to clear the backlog because labs don't have the capacity to process all the tests fast enough.

In Newham around 10 percent of people downloaded and used the NHS app, while in other areas the uptake has been approximately 30 percent.

Now the app has at last been launched, the government is now hoping people will download it in much greater numbers.