REACT-2.5: Seroprevalence of SARS-CoV-2 antibodies

This cross-sectional study estimates SARS-CoV-2 IgG antibody seroprevalence in the community in England using self-administered LFIAs

Keywords: SARS-CoV-2; COVID-19; prevalence; PCR; virus; point-of-care diagnostics

Q&A with the REACT team: REACT researchers Dr Atchison and Prof Barclay host a public Q&A session on antibody testing.

Short of a vaccine, testing is the only way out of lockdown.

Prof ara darzi

Description of the Study:

  • Title: REACT-2: a study of SARS-CoV-2 antibody seroprevalence in the community in England.
    – Study 5: National seroprevalence study of SARS-CoV-2 antibodies using a lateral flow immunoassay self-administered test
  • Principal Investigators: Steven Riley, Christina Atchison, Deborah Ashby, Christl A. Donnelly, Wendy Barclay, Graham Cooke, Helen Ward, Ara Darzi and Paul Elliott.
  • Centers of Implementation: Imperial College London, Imperial College Healthcare NHS Trust and Ipsos MORI.
  • Study Population: 100,000 to 200,000 individuals in England.
    – Inclusion criteria: Adult ≥ 18 years old.
    – Exclusion criteria: Individuals with a medical condition (or are taking medication) that might increase bleeding risk from self-delivered finger prick with a lancet.
  • Type of study: Cross-sectional study.
  • Design: Repeated cross-sectional surveys of seroprevalence using self-administered LFIAs from a series of age-stratified representative population samples of 100,000 to 200,000 individuals in England. The age range is 18 years and above.
  • Methods: Test kits and instructions are delivered by post to people who register for the study. Participants reporting positive antibody tests and a similar sample of those who test antibody negative and who report an invalid test result are followed up 2–4 weeks after completing the antibody test to assess COVID-19 preventive behaviour and whether these behaviours changed as a result of having read their antibody test result.

Objectives of the Study:

Principal Objective: To estimate SARS-CoV-2 IgG antibody seroprevalence in the community in England. We estimate seroprevalence as the proportion of individuals who have a positive IgG result.

Secondary Objectives: Prevalence and nature of symptoms comparing infected and uninfected individuals. In addition, the durability of immune responses is evaluated in those with proven infection.

More about this Study:

REACT-2 is a series of five sub-studies towards establishing the seroprevalence of antibodies to SARS-CoV-2 in England as an indicator of historical infection. The main study (study 5) uses the same design and sampling approach as REACT-1 using a self-administered lateral flow immunoassay (LFIA) test for IgG antibodies in repeated samples of 100,000 to 200,000 adults aged 18 years and above. To inform study 5, studies 1-4 evaluate performance characteristics of SARS-CoV-2 LFIAs (study 1) and different aspects of feasibility, usability and application of LFIAs for home-based testing in different populations (studies 2-4).

Conclusions: The REACT-2 results and statistics can be found on this page.

REACT: The REal-time Assessment of Community Transmission (REACT) programme is a series of epidemiological studies that are seeking to improve understanding of how the COVID-19 pandemic is progressing across England. To do this, the programme is carrying out two major pieces of work that are looking at the possibility of using home sampling and testing to track the infection. REACT-1 programme is monitoring coronavirus infection levels over time, while REACT-2 programme is assessing antibody finger-prick tests and using these to estimate how far the virus has spread.

Together REACT-1 and REACT-2 will improve our understanding of the transmission of the virus in the community to help guide policies on continued social distancing and other control measures.

Other studies of REACT:A study of SARS-CoV-2 virus prevalence in the community in England“, “Clinical and laboratory evaluation of SARS-CoV-2 lateral flow immunoassays“, “Public involvement and pilot testing to assess the feasibility of in-home self-testing for SARS-CoV-2 antibodies“, “Acceptability and usability study of in-home self-testing for SARS-CoV-2 antibodies in a population-based sample” and “Usability and validity of LFIA self-testing in key workers, including the assessment of dry blood spots for SARS-CoV-2 antibody detection and saliva for SARS-CoV-2 viral detection

Imperial College London

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