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The government has announced a home testing programme for coronavirus to track levels of infection in the community.
Dr Penny Ward, Visiting Professor in pharmaceutical medicine at Kings College London and the Chair of the Education and Standards Committee of the Faculty of Pharmaceutical Medicine, said:
Is this using the ‘have you got it’ swab test or the ‘have you had it’ antibody test; or both?
“Both (swab test in React 1 and antibody test in React 2).
How will tracking spread of the virus help identify an accurate antibody test?
“It might enable identification of infected persons who can then be tested for antibody levels at various points after infection is identified.
What is the difference between what REACT-1 and REACT-2 will achieve?
“REACT 1 might provide some information on the current community attack rate (the number of people in the community who are infected at the point in time over which the investigation is run). REACT 2 might provide information on the number of people in the community who have been infected at any time since the epidemic began (likely to be a bigger N than the number currently infected).
How will we find out if the antibody tests are accurate?
“We can only know this by conducting serial testing in individuals we know are/have been infected and comparing the number of positive antibody tests to the N identified by swab testing. Currently some of the rapid antibody tests are only positive in ~50% of individuals who have had a positive swab (PCR) test – i.e. they only detect 1 in every 2 people that have been infected.
What is the difference between established lab antibody tests and the home antibody test kits being investigated here?
“The lab antibody tests are generally more accurate than the home antibody test kits (i.e. they may detect 9/10 persons that have been infected) but they need more blood and take longer to run.
Is this a sensible project – will it help?
“It is an attempt to get a handle on what is happening in the community: it is a great shame that this was not going on throughout the epidemic.”
Dr Colin Butter, Associate Professor in 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.
“The data that presently exist for coronavirus infection centres around two parameters: positive laboratory tests for the virus which, until very recently, have only been conducted when a patient is admitted to hospital, and deaths that come from these. 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. In epidemiological language this is called the prevalence of the disease. 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 Ro, the basic reproductive ratio of the virus, below 1.
“In REACT-1 a random 100,000 individuals will be asked to supply nose and throat swabs, which will be returned for laboratory analysis to detect the presence of the coronavirus (“have I got it”). This will answer the question of how widely spread the virus is in the population: presently the UK is reporting around 4,000 new cases every day but with asymptomatic infections and those not requiring hospitalisation this figure will be many times higher.
“In REACT-2 an at-home test for antibody to the virus (“have I had it”) will be validated against a gold-standard laboratory test. If an initial series of trials proves this to be reliable it will be stepped up to 100,000 individuals.
“Taken together, the results generated from REACT strategy will add much needed detail to an understanding of the infection dynamics of the pandemic. They are also likely to contribute to answering the critical question regarding the nature of functional immunity in COVID “if I have had it can I get it again”.”
Prof Gary McLean, Professor in Molecular Immunology, London Metropolitan University, said:
“This initiative is a really good one.
“The proposed study will investigate both virus (have you got it) and antibody (have you had it) in a random sample of the population. 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.”
Dr Steven Riley, Professor in Infectious Disease Ecology and Epidemiology, Imperial College London, said:
“I am a co-investigator on this project. 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, REACT-1 could be repeated to assess the impact of any increased social contact.”
Dr Joshua Moon, research fellow in sustainability research methods in the Science Policy Research Unit at the University of Sussex Business School, said:
“This is like comparing the ‘have you got it’ PCR test with the ‘have you had it’ antibody test. So REACT-1 is the baseline which will look at the total prevalence of covid-19 in the sample. REACT-2 then distributes antibody tests which, now that we have a known positive or negative for everyone in the sample, will tell us how well the antibody test is actually doing in terms of false negatives or false positives.
“The biggest difference between established lab antibody tests and the home antibody tests is the person doing it and the equipment being used. In the lab a professional scientist is using known reagents and monoclonal antibodies to test blood samples and interpret the results. At home, the test is being done by your average person using a testing kit which has spent time in transit and using a less-than-ideal blood sample with interpretation being done by the person being tested. This involves a lot more uncertainty as training and interpretation will play a role in how well the test works.
“Overall, the project itself is a sensible one to do and will tell us about the applicability of home-administered antibody tests. The better we can understand these tests, the better our use of them for testing, tracing, and isolating will be, meaning a much safer return to pre-lockdown conditions.”
All our previous output on this subject can be seen at this weblink:
www.sciencemediacentre.org/tag/covid-19
Declared interests
None received.