A test to find out whether people have been infected with coronavirus in the past has been approved by health officials and could be rolled out within weeks.

Frontline health workers are expected to be first in line for hte test. 

Public Health England (PHE) said the antibody test, developed by Swiss pharmaceutical giant Roche, was a "very positive development" after experts at its Porton Down facility gave it the green light.

The test - which Prime Minister Boris Johnson has previously called a "game-changer" - picks up 100 per cent of cases where somebody has had coronavirus in the past.

Here, we answer the key questions surrounding the new test.

  • What is the new test?

Pharmaceutical giant Roche has developed a test which can tell whether somebody has ever had coronavirus.

The test involves taking a small sample of blood and testing it for antibodies which will indicate exposure to coronavirus.

Public Health England (PHE) has evaluated the new Roche test and has approved it as being safe and reliable for widespread use.

  • How reliable is it?

Very. The test picks up 100 per cent of people who have had coronavirus.

This means it has 100 cent sensitivity.

It also has a specificity of over 99.8 per cent - meaning it picks up virtually all people who have not had coronavirus.

A test that is 100 per cent specific means all healthy individuals are correctly identified as healthy - there are no false positives.

  • What if I've never had any symptoms of Covid-19?

It doesn't matter.

Experts believe a proportion of people who have had Covid-19 never actually develop symptoms.

The new test can identify people who have had coronavirus even if they have never had any indication they are infected.

  • If the test shows I've had Covid-19, am I now immune from it?

Scientists are unsure and there is still a lot to learn about coronavirus.

Experts believe that while the presence of antibodies indicates a level of immunity, it is unclear whether people are completely protected and how long any immunity lasts.

There has been some suggestion that immunity could last for two to three years but more work needs to be done.

Can I get the new test?

Not yet. The Government plans to first roll out the test to front-line workers such as those in health and social care.

It is hoped the test will become available to the wider public, although it is unclear whether this will be via the NHS or through commercial websites.

Roche says it will be able to provide hundreds of thousands of antibody tests to the UK every single week.