A new form of Covid-19 test which can produce results in just 15-30 minutes is set to be rolled out across the globe, the World Health Organisation (WHO) has announced.

Here, the PA news agency looks at some of the key questions surrounding the rapid antigen tests.

– How does this new test work?

The antigen-based rapid diagnostic tests work by detecting proteins found on the surface of the virus.

The tests, which look similar to pregnancy tests and can yield results within 30 minutes, simply display two blue lines for a positive result.

The WHO last week approved the tests for emergency use.

– How do they differ from other tests?

The main difference between rapid-antigen tests and nasal/throat swabs and finger-prick blood tests is the antigen tests do not require laboratory processing to produce results.

This means they are able to detect coronavirus infection within minutes, compared to the hours or days necessary for the genetic tests, known as PCR tests, to turnaround results.

They are also far cheaper, with each test costing just 5 US dollars (£3.90) each.

However they are generally considered less accurate than laboratory-based tests.

– How important are these new tests in the fight against coronavirus?

The rapid antigen tests will be vital in improving the testing capacity of lower and middle-income countries who lack enough laboratory resources or trained health workers to properly carry out PCR tests.

They will also allow health care workers to get a better grip on where the virus is circulating in poorer countries, in hopes of following up with containment and other measures to stop it.

Peter Sands, executive director of the Global Fund, a partnership that works to end epidemics, said the tests represent a “significant step” in the effort to combat and contain the virus on a global scale.

He said: “They’re not a silver bullet, but hugely valuable as a complement to PCR tests.”

– When will the tests be rolled out?

The WHO and its leading partners have agreed to deploy 120 million rapid-diagnostic tests as early as next month.

Catharina Boehme, chief executive of a non-profit group called the Foundation for Innovative New Diagnostics, said the initial rollout would take place across 20 countries in Africa.

– What do the new tests mean for the UK?

While poorer countries will primarily benefit from the rapid-antigen tests, wealthier countries who have signed up to the Access to Covid tools initiative, which the UK has, will also be given access to them.

They represent a potential boon to the Government’s Operation Moonshot scheme for mass testing, though it is not clear if they intend to buy these tests.

Health Secretary Matt Hancock previously said mass testing was the nation’s “best chance” of reducing social distancing measures without having a vaccine.

– What have other people said about antigen tests?

Former prime minister Tony Blair has called on the Government to adopt the rapid antigen tests, saying they could enable an extra 300,000 coronavirus tests to be carried out every day within a few weeks.

However Baroness Dido Harding, the head of NHS Test and Trace, warned companies and individuals could be forced to foot the bill for the swift turnaround tests as they were too unreliable for use within the health service.

But she said those without symptoms might choose to pay for the tests to act as a kind of Covid-19 passport to allow them to take part in non-socially distanced activities.