How does our COVID-19 testing process work?

illustration of coronavirus cell

Last week, we brought you news that up to 10,000 NHS workers will be tested for coronavirus per day, after labs were repurposed at our founder member, the University of Birmingham. Our fellow members at University Hospitals Birmingham and Birmingham Women’s and Children’s Hospitals will be the first to benefit, alongside colleagues from West Midlands Ambulance Service.

In this Q&A Professor Andrew Beggs, who is leading the testing, explains more:

How does the test work?

Here, we do viral PCR testing which has also been called antigen testing, which begins with a swab from the patient.

We first have to make the swabs safe to ensure that the virus doesn’t infect those who are carrying out the test. To do that it must be inactivated using a special chemical which is added to the swab or by heating it at 75 Celsius for 15 minutes – the process is similar to the way that milk is pasteurised. This process kills the virus but leaves its genetic code intact.

We then amplify this code using a technique called PCR, which makes the virus’ signal big enough to detect. As it amplifies, it omits pulses of light which are detected using a Real Time PCR Machine. This signal allows us to tell whether a swab has the virus on it or not. We then do quality control of the result and it is sent back to the hospital or the doctor who has requested it. From receipt of the sample to getting the results take around 5 hours in total.

How accurate is the test?

The test we are using is very accurate. We’ve compared it to the test that the NHS currently uses and found that it agrees around 95% of the time. More importantly, it detects everyone who has the virus. Overall, these tests have an accuracy of about 85 to 95%, but much of this depends on how a swab is carried out – so it’s really important that this is carried out thoroughly. If the swab is not carried out properly, the test may not work as there is not enough virus on the swab to detect.

What facilities do you have for testing?

As well as Category 3 labs, we have 14 Real Time PCR machines here. We also have three liquid handling robots to help us prepare the samples. With this, we have the potential to deliver up to 10,000 tests per day. However, to deliver this amount of tests, it is important that all steps of the process from swabbing and RNA extraction to the PCR testing can be scaled up to meet this need and that is where we’re concentrating our efforts at the moment.

How are results fed back to NHS staff?

Results will be reported back to the NHS trust, then communicated to NHS staff via online pathology systems.

How will staff be prioritised for testing?

Initially testing will prioritise those staff who are self-isolating at home because they or a member of their household have symptoms.

How many tests will be done a day?

Initially 150 from UHB, with further staff from WMAS and BWC. Capacity within the University’s labs mean that there is scope to increase this to 10,000 a day should it be required.

Can staff self-refer to be tested?

Yes – they will contact teams at the Trust to arrange for swabs to be taken.

Find out more about all the Covid-19 research activity taking place across BHP by visiting our Covid-19 Resource Centre.