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In April 2020 the UK Government’s Department of Health and Social Care initiated the REal-time Assessment of Community Transmission (REACT-1) programme, an unprecedented real-time population study into the prevalence of COVID-19 across England. 

Behind the study are experts in epidemiology and public health at Imperial College London, who have been leading the design of the research, and the analysis, interpretation and dissemination of the findings to the public and policy-makers.

Supporting the study is collaborators Ipsos MORI, a social and market research organisation which has utilised its experience in data collection and social research to establish the logistics and data collection processes required to undertake the study.

The testing process involves a vast amount of infrastructure across the country, from sending out test kits for home use, to sorting huge numbers of test kits, storage of swabs at the correct temperature and eventual lab testing, including genetic testing to identify variants.

After testing, data is shared with colleagues at Imperial, where epidemiological analysis of the tests produces weighted prevalence estimates by age, geography and employment type, as well as an ‘R number’ to show the trajectory of the virus’ prevalence across England, as well as the spread of variants over time.

All this has proven essential in the UK’s COVID response providing the Government with case reporting on a monthly basis and evidence for policymaking around restrictions and relaxation. The study is now also being used to track vaccine effectiveness to ensure that the vaccines are working as they should against new variants.

The REal-time Assessment of Community Transmission (REACT-1) programme provided an essential tool in the fight against COVID-19, allowing the UK Government to track the spread of the disease in real-time and to react accordingly.

But in order to really understand the spread of the disease beyond those who currently have COVID, the study team worked together to establish REACT-2, a nationwide at-home antibody study with the aim to assess how far COVID-19 infection has already spread.

Antibodies are essential in our fight against disease and are a part of the immune system which is able to build an innate response to antigens caused by disease. To test for antibodies a finger prick test is used. As part of REACT-2, nearly 1 million participants were sent test kits.

With a more complex test, it was also essential to work with the public to ensure the tests were as accessible and user-friendly as possible and that messaging was clear and focused. Indeed a key part of the study was to determine whether at-home testing for antibodies was possible, and how best to carry it out. This was done through zoom calls, as well as through a user survey that went to every participant.

The results of REACT-2 have been critical in understanding the disease, and an increase in antibodies was detected as the pandemic progressed. These results have helped inform policy as well as providing a broader understanding of the pandemic, setting the UK up well to manage the spread of COVID-19 into the future.

Following the first two REACT studies, Imperial College London established REACT-LC to help track and understand why different people experience COVID-19 differently, and what underlying biology is a factor in who suffers from Long COVID.

At Imperial’s Long COVID Clinics around England participants are interviewed and a number of tests performed for weeks and months after they’ve tested positive from COVID-19. From blood tests, to height and weight measurements and tests of fitness, the study has recruited over 10,000 people who have tested positive for the virus and is following them up through questionnaires, cognitive tests and routine records.

Key to understanding how the disease works is genetics, and in collaboration with Genomics England genomic analysis is being used to better understand how the disease works, and how it’s effects might differ from person to person. The study is also involving other experts with expertise in omics data.

In addition, the study will be following up tens of thousands of people through questionnaires and cognitive tests and linkage to their health records to understand the long-term consequences of infection with SARS-CoV-2and to understand better what constitutes Long COVID

The study is ongoing, but results have already given us a significantly better understanding of Long COVID, and more hope for those who are or might be impacted by the disease into the future.

Though progress in the fight against COVID-19 seems to be being made, it’s these kinds of studies across the REACT program that will arm researchers and policymakers in the UK, and around the world, with the knowledge needed to keep fighting the disease and to ensure a return to normality as soon as possible to world over.

Professor Helen Ward, Professor of Public Health at Imperial College London, talks about her involvement in the REACT study to assess a range of different antibody tests for their accuracy against SARS-CoV-2 (the virus that causes COVID-19) and how easily people can use them at home.

Professor Graham Taylor, Professor of Human Retrovirology in the Department of Infectious Diseases at Imperial College London, is part of a team carrying out antibody testing to assess if a person has previously been infected with the coronavirus that causes COVID-19. At the Imperial College Academic Health Science Centre (AHSC) COVID-19 webinar series, he talked us through how teams at St Mary’s Hospital and North West London Pathology based at Charing Cross Hospital, part of Imperial College Healthcare NHS Trust, were performing developing and testing antibody tests to inform a nationwide study.

Dr Christina Atchison and Professor Wendy Barclay gave a live Q&A session on 22 July to share all things testing, from why antibody testing is helping our response to the outbreak, to why it's too soon to rely on them to change our behaviour. They responded to questions posed by a live online audience.

Researchers at Imperial College London have been working with clinicians at Imperial College Healthcare NHS Trust on a programme of work to develop a ‘gold standard’ antibody test that can be used widely to track rates of coronavirus infections in the UK’s population.