Guidance

NHS Test and Trace: how we test your samples

Updated 16 June 2021

An overview of the largest diagnostic network in British history, including what happens after you have submitted your sample and how the laboratories process your test.

The national laboratory network

Since the start of the pandemic, we have vastly expanded the nation’s testing capacity by establishing the largest network of diagnostic testing facilities in British history, including the public and private sector, NHS Trusts, Public Health England (PHE) laboratories, and not-for-profit organisations.

We have scaled the use of rapid, asymptomatic testing across the country, but we continue to test individuals using laboratory-based methods. This is to diagnose people with symptoms, detect variants of concern, understand how the virus is spreading and provide diagnostic confidence by confirming test results. COVID-19 swab samples are sent to our laboratories from across the country for analysis. We receive samples from testing sites, such as COVID-19 drive-through and walk-through testing centres, and the NHS on the front line.

We continuously review our laboratory requirements as the pandemic progresses to ensure that we have the capacity, so anyone who needs a test can get one.

The importance of the national laboratory network

We have built a vast national laboratory system at incredible speed over the past year and have set up an entirely new nationwide network of testing sites to make sure everyone who needs a test can get one.

Testing remains a vital part of our response to COVID-19 as we start to cautiously ease lockdown and as the nature of the pandemic continues to evolve.

We have invested in new innovative testing technology which means we can operate faster and respond to surges in demand.

We have also increased staff levels and used robotics to process more tests and improve turnaround times.

Our aim is that the UK has a resilient, long-term, PCR testing capacity that serves the whole nation.

Types of laboratory: the different arrangements

There are different types of laboratories processing COVID-19 swabs.

At the same time as expanding NHS and PHE capacity as quickly as possible – which forms pillar 1 of the testing programme – the government has set up a network of Lighthouse laboratories, partner laboratories and testing sites in partnership with a variety of suppliers, including NHS trusts, commercial suppliers, academia and not-for-profit organisations.

We have also rolled out Mobile Processing Units which are mobile laboratories that allow sample processing to be completed near testing sites, providing results more quickly.

All of this has enabled the processing of test samples from an entirely new network of testing sites across the UK and from alternative routes such as home testing and mobile testing units.

Lighthouse laboratories

A Lighthouse laboratory is a high throughput facility that is dedicated to COVID-19 testing for NHS Test and Trace.

The Lighthouse laboratories were set up by experienced scientific executives and technical leaders with decades of experience. The rapid and sustained growth and independent quality assessments is evidence of this.

Each Lighthouse laboratory has been reviewed by experts and is supported by an external expert clinical virology advisor who provides challenge and support to the laboratory team on behalf of NHS Test and Trace.

The Lighthouse laboratories are managed through the Department of Health and Social Care (DHSC), NHS trusts, commercial suppliers, academia and not-for-profit organisations.

Partner laboratories

A partner laboratory provides a high volume of testing for NHS Test and Trace alongside its usual activities.

These laboratories are different to Lighthouse laboratories. The laboratories can be acquired through partnership agreements with the public, private and academic sectors and can contribute tens of thousands of tests to the overall testing capacity.

The journey of a swab: what happens to your swab

Testing plays a vital role in our effort to fight and contain coronavirus; helping to mitigate the spread of the disease and preventing further transmission.

With hundreds of thousands of swabs processed in our laboratories every day, the experience of taking a coronavirus test at home or at a test site is now familiar to many people in the UK, but the next steps in the process are far less visible.

Here is a summary of what happens ‘behind the scenes’ after your sample enters one of our laboratories for testing. Please note that the processes will vary slightly between laboratories. New types of testing may be used in your area using a different process, but results will be communicated in the same way. The following process relates to PCR testing only.

1. Samples arrive at the laboratory double-bagged and in sealed plastic containers. Each one has its own unique barcode.

2. A laboratory operator in protective clothing removes the sample from its bags, inside a biosafety cabinet. These cabinets have negative air pressure such that no aerosol particles can escape into the room and harm the laboratory operators.

3. The operator makes sure the sample is viable: that there is enough liquid in the tube and the barcode is in the right place.

4. Next, the liquid is removed from the sample tube and mixed with a chemical that kills any live virus so it can be handled safely. The sample is then prepared for ribonucleic acid (RNA) extraction, where any genetic material found in the sample is extracted.

5. The samples are added to a machine that uses magnets to extract and wash the RNA. The purified RNA is then placed on ice inside an insulated container to keep it stable.

6. Plates of purified RNA are removed from the ice and mixed with a number of chemicals called ‘reagents’. These are placed into a polymerase chain reaction (PCR) machine.

7. PCR testing works by cycling the RNA samples through a variety of different temperatures, a number of times. Each cycle triggers a chain reaction that causes the genes (if present) to replicate and release a detection chemical which tells us if coronavirus RNA is present in a sample.

8. Once the PCR reaction has been run, the results are carefully checked before being released and uploaded to the laboratory’s Laboratory Information Management System (LIMS), and then sent on to the National Pathology Exchange (NPEx).This is where the result from the laboratory is matched to the sample barcode (originally scanned) and subject record.

9. All results are sent to the NHS Business Services Authority (BSA) who send email and SMS results to the person who took the test. For results relating to England, NPEx matches them to an NHS number and GP record if possible. NPEx also sends all the data to NHS Digital, who split out which results need to go to England, Scotland, Wales and Northern Ireland for public health responses, who then share the information with local authorities.

Locations of the laboratories

We have Lighthouse laboratories and partner laboratories operating with a range of partners across the UK.

A laboratory is located in each Devolved Administration and the geographical spread of the laboratory network allows us to deliver quick turnaround times for tests taken in any part of the UK.

A new very high throughput laboratory in Royal Leamington Spa will also begin processing tests soon. This laboratory will be publicly owned and run by DHSC as part of the NHS Test and Trace laboratory network.

Automation and technology

As well as building a vast new laboratory network, NHS Test and Trace has invested in new innovative testing technology which means we can operate faster and with increased capacity and develop a flexible pandemic response infrastructure that can respond to surges in demand.

This includes the LGC Biosearch Technologies’ EndPoint PCR (EPCR) testing system for COVID, which has ultra-high capacity and can process up to 150,000 tests each day on a single instrument with a lower cost per test than current RT qPCR. We intend to use this technology in our two largest labs; Royal Leamington Spa and Milton Keynes.

In addition, new technology to rapidly detect COVID mutations indicating whether positive test samples contain known variants is being rolled out by the government in NHS Test and Trace laboratories.

The technology – known as ‘genotype assay testing’ – is set to halve the time it currently takes to identify if a positive COVID-19 sample contains a mutation indicative of a known variant of concern, and will be used in addition to standard testing for COVID-19 to identify cases quickly.

Genotype assays complement existing surveillance work that uses genomic sequencing to look for variants in COVID-positive samples. Genomic sequencing surveillance will continue to detect new variants and mutations. Where new variants or mutations are identified, the technology can be adapted to test for them as well, meaning the technology can be easily deployed to track the variants of most concern.

The people behind your swab

A skilled workforce from across the scientific community, with the relevant expertise and experience needed to carry out COVID-19 testing, is working tirelessly to process the samples received. We are extremely thankful for their support and dedication at this time of national need. This work is absolutely crucial in the effort against COVID-19 and enabling the return of more normality to our lives.

The expansion of the laboratory network has resulted in a number of exciting new roles, from junior positions utilising a broad skill base, through to senior positions requiring experienced specialists or those able to oversee entire laboratories.

We will continue to run a rolling recruitment campaign to support the laboratories network and build new jobs and careers in science and the diagnostics industry.

Further information

• Coronavirus (COVID-19): scaling up testing programmes (policy paper)
• Industry responds to call to arms to build British diagnostics industry at scale (press release)
• Weekly statistics show NHS Test and Trace is reaching the highest number of contacts (press release)
• NHS Test and Trace managing record number of cases (press release)
• Three Lighthouse laboratories begin testing for COVID-19 (press release)
• Groundbreaking new technology to detect known variants of concern (press release)