- 22 September 2020
Jonny Pearson-Stuttard, RSPH Trustee and Public Health Doctor at Imperial College London, sets out what steps have been taken by the UK Government to test people for Covid-19 and why testing is so important in tackling the spread of the virus.
Testing for Covid-19 has been increasingly topical in recent weeks. The WHO Director General has stated “You can’t fight a virus if you don’t know where it is”. As hospital admissions and deaths continue to rise in the UK and testing numbers lag behind countries such as Germany, Matt Hancock announced a five-pillar plan to reach 100,000 tests a day. This has provoked discussion around the importance of testing and how it can help throughout the various stages of this pandemic.
Testing provides data
Epidemiology is the study of disease according to time, place and person; knowing this information is key when implementing (and knowing when to lift) effective measures, such as social distancing. These are crucial to stop transmission and limit the health impacts. What makes Covid-19 so difficult is that it is a new virus which means our understanding of the virus and data characterising its spread and health effects is evolving all of the time. Testing for Covid-19 can provide data to help our understanding of the epidemic and inform policy.
There are two broad categories of tests for Covid-19 in the Government’s testing strategy; those that test for the presence of active virus using swabs dubbed ‘swab testing’ and those that test for antibodies which detect the presence of past infection and the development of immunity. These tests have different uses in the response to Covid-19.
Swab tests for presence of viral infection
The swab tests to detect active viral infection have been available and used since the first suspected cases here in the UK. Initially, around 500 tests per day were done and this increased to around 11,000 per day by the end of March through using Public Health England and NHS laboratories only. The Government plans to increase this testing capacity to 25,000 by the end of April – pillar one of their testing strategy. Pillar two aims to increase total capacity to 100,000 tests a day by bringing university and commercial laboratories online with other swab tests, including those which are point-of-care and with faster results than traditional approaches.
To increase testing capacity from 500 to 100,000 a day in a short time provides several challenges across supply chains, skill sets and facilities. Other countries, such as Germany, have been testing 500,000 a week since the end of March. The Government have pointed to the lack of a big diagnostics manufacturing industry in the UK as one barrier to scaling up testing as quickly as other countries. However, the strategic error to delay expanding testing capacity wider than PHE and the NHS, to university and commercial partners has also played a part in this delay.
Antibody tests for past infection and immunity
The antibody tests aim to detect whether an individual has previously had the virus and now has immunity; the Government’s strategy has two approaches for this. First, to conduct UK wide surveillance testing, using PHE labs, to learn about the spread of the disease and understand where, when and in whom immunity for Covid-19 has developed (Pillar 4 of the strategy). Second, to increase the capacity and accessibility of antibody testing (through home test kits for example) through developing and evaluating new approaches to antibody testing including from commercial partners (Pillar 3). So far, however, none of these tests have been good enough or reliable enough to be used and rolled out.
Data informs the response to Covid-19
In the first phase of the epidemic, community swab testing of those with symptoms and their close contacts (traditional contact tracing) was carried out to ensure those with Covid-19 isolated at home to reduce the risk of community transmission. However, with limited testing capacity, this was halted as hospitalisations increased. Swab testing has since been predominantly used on patients in hospitals to enable the best care and reduce the risk of transmission to fellow patients and healthcare workers through relevant protective measures.
Over the last two weeks (before 9 April 2020), swab testing has been gradually deployed to healthcare workers. Around 20,000 NHS staff and families have been tested to date, which is just a fraction of the workforce. Regular testing of healthcare workers is vital; without a test, staff must isolate for 7 or 14 days if they have symptoms or their household contacts do. A test could confirm if they do or do not have Covid-19, allowing them to continue working if they test negative, rather than having unnecessary time away from the front line. With one in four doctors reported recently as off-sick, this could make a big difference to how the NHS can cope with the increased pressures.
Going forward, swab testing must be rapidly ramped up to provide regular and comprehensive testing for healthcare workers followed by other key workers to ensure our vital services can keep moving at this time of crisis. Swab testing will continue to be vital throughout and after this initial outbreak.
Community mass testing would provide important data throughout each stage of the epidemic. This could help monitor the progression of the epidemic and how it varies by geography, age and other demographics. This would allow close and real-time evaluation of whether the social-distancing measures are working, and importantly track community transmission when they are removed, to inform a more targeted and local approach to future measures. Mass testing can provide scientists with other information too, such as whether the virus is mutating and if so how. Alongside this, the antibody surveillance programme that estimates levels of past infection and potential immunity nationwide, and in different sub-groups, are vital. This would provide data to enable lifting of measures in a step-wise manner to balance the drive to get lives and livelihoods back to normal against the risk of the virus returning at pace.
Throughout the epidemic, testing will be crucial to provide the data that informs the decisions that will affect thousands of lives. Having detailed estimates of where, when and who has the virus and/or immunity can tip the balance in our favour in the battle against Covid-19. As with so many public health challenges, data holds the key to turning the tide of Covid-19.