Scientists have welcomed news that 100,000 people in the community will be randomly sampled for Covid-19 as the Government moves towards larger-scale testing to help ease the lockdown.

Experts said the testing programme will “fill gaps in our knowledge” about how prevalent coronavirus is in the general population, with testing forming a key plank in how the lockdown may be relaxed.

The Department of Health announced the move on Wednesday evening, saying swab tests would be sent to 100,000 randomly selected people across England as part of the Real-time Assessment of Community Transmission (React1) trial.

Scientists are also assessing antibody tests with the intention of them eventually being used at home in a second phase of the study, named React2.

Antibody kits, which detect whether the body could have built up immunity to the virus, will first be handed out to 300 volunteers from Imperial Healthcare NHS Trust to determine accuracy.

After that, 10,000 volunteers and 5,000 key workers will be invited to read the results taken from a finger prick of blood combined with a dye.

If the antibody test works with a high degree of accuracy, the kits will be rolled out to 100,000 people later in the year.

The trial is being led by Imperial College London alongside colleagues at Imperial College Healthcare NHS Trust, and pollster Ipsos Mori will use self-sampling like that used in diabetes medicine.

Professor Paul Elliott, director of the programme at Imperial College London, said: “Community testing is a vital next step in ongoing efforts to mitigate the pandemic, but to be successful this must be based on robust scientific evidence.

“Through this important programme we will gather the critical knowledge base necessary to underpin community testing programmes and facilitate a greater understanding of the prevalence of Covid-19 in the UK.”

Colin Butter, associate professor at the School of Life Sciences, University of Lincoln, said: “The new programme of home testing, announced by the Department of Health, seeks to fill gaps in our knowledge about the pandemic.

“Since many infections are controlled well, not requiring hospitalisation, and still more are asymptomatic, we have only a rough estimate of how many individuals are presently infected.

“We also do not know how many people have been infected, recovered and are now presumed to have a level of immunity to reinfection.

“This knowledge will be vital for modellers seeking to understand the detail of the pandemic and to the design of strategies to ease lockdown whilst keeping R, the basic reproductive ratio of the virus, below one.”

Gary McLean, professor in molecular immunology at London Metropolitan University, said: “This initiative is a really good one.

“Because the study aims to compare tests and also use samples from NHS workers already known to have been infected, it will provide details about how reliable the tests are in terms of false positive and false negative results – this is particularly for the ‘have you had it’ results.

“React1 is a test for presence of virus – the ‘have you got it’ test – whereas React2 is a test for ‘have you had it’ – the antibody test.

“Together these will provide a lot of information about spread of the virus within the community and perhaps in people that may have been unaware they had been infected.

“The numbers of proposed samples appear to be enough to provide statistically relevant results.”

Steven Riley, professor in infectious disease ecology and epidemiology at Imperial College London and co-investigator on the study, said: These are exciting studies that could give us a much clearer picture of where the virus is in the community.

“When we transition out of lockdown, React1 could be repeated to assess the impact of any increased social contact.”