Publications

2026 

Whitaker M, Elliott J, Gerard-Ursin I, Donnelly CA, Ward H, Elliott P, Chadeau-Hyam M. Profiling vaccine attitudes and subsequent uptake in 1·1 million people in England: a nationwide cohort study The Lancet, 2026; 407, 350-362

2025

Guzmán V, Di Gravio C, Cooper E, Lound A, Smith N, O’Hara M, Atchison CA, Cooke G, Chadeau-Hyam M, Elliott P, Ward H. “I put a lot of emphasis on work because I want to keep my job”: A population-based interview study of Long COVID and employment changes in England. Health Expectations, 2025; 28:e70476 

Cooper E, Lound A, Jones K, Bruton J, Day S, Atchison CJ, Eccles C, Piper A, Cooke GS, Chadeau-Hyam M, Elliott P, Ward H. Recognition, support and self-management in Long Covid: a population-based qualitative study Health Expectations 2025 Oct;28(5):e70428 

O'Mahoney LL, Routen A, Gillies C, Jenkins SA, Almaqhawi A, Ayoubkhani D, Banerjee A, Brightling C, Calvert M, Cassambai S, Ekezie W, Funnell MP, Welford A, Peace A, Evans RA, Jeffers S, Kingsnorth AP, Pareek M, Seidu S, Wilkinson TJ, Willis A, Shafran R, Stephenson T, Sterne J, Ward H, Ward T, Khunti K. The risk of Long Covid symptoms: a systematic review and meta-analysis of controlled studies. Nat Commun. 2025 May 7;16(1):4249. doi: 10.1038/s41467-025-59012-w. 

Whitaker M, Rodrigues S, Cooke G, Virlon B, Donnelly CA, Ward H, Elliott P, Chadeau-Hyam M. How COVID-19 affected academic publishing: a three-year study of 17 million research papers. Int J Epidem 2025;54(3): dyaf058, https://doi.org/10.1093/ije/dyaf058

Morales I, Nguyen VK, Abd El Aziz M, Sultani A, Bärnighausen T, Becher H, Ciesek S, Kampmann B, Lange B, Rupp J, Scheithauer S, Ward H, Karch A, Denkinger CM. Responsive population-based cohorts as platforms for characterising pathogen- and population-level infection dynamics for epidemic prevention, preparedness and response. Euro Surveill. 2025 Jun;30(25):2400255. doi: 10.2807/1560-7917.ES.2025.30.25.2400255.

Mumford L, Hogg R, Taylor A, Lanyon P, Bythell M, McPhail S, Chilcot J, Powter G, Cooke GS, Ward H, Thomas H, McAdoo SP, Lightstone L, Lim SH, Pettigrew GJ, Pearce FA, Willicombe M. Impact of SARS-CoV-2 spike antibody positivity on infection and hospitalisation rates in immunosuppressed populations during the omicron period: the MELODY study. The Lancet 2025;405:314–328. https://doi.org/10.1016/S0140-6736(24)02560-1

Atchison CJ, Gilby N, Pantelidou G, Clemens S, Pickering K, Chadeau-Hyam M, Ashby D, Barclay WS, Cooke G, Darzi A, Riley S, Donnelly C, Ward H, Elliott P. Strategies to increase response rate and reduce non-response bias in population health research: a series of randomised controlled trials during a large COVID-19 study JMIR Public Health Surveill 2025: 2025:11:e60022. doi: 10.2196/60022

2024

 Hampshire, A., Azor, A., Atchison, C., Trender, W., Hellyer, P. J., Giunchiglia, V., Husain, M., Cooke, G., Cooper, E., Lound, A., Donnelly, CA., Chadeau-Hyam, M., Ward, H., Elliott, P. (2024). Cognition and Memory after Covid-19 in a Large Community Sample.. N Engl J Med, 390(9), 806-818. doi:10.1056/NEJMoa2311330

 Mills, C., Chadeau-Hyam, M., Elliott, P., Donnelly, C. A. (2024). The utility of wastewater surveillance for monitoring SARS-CoV-2 prevalence. PNAS Nexus, 3(10), 438. doi:10.1093/pnasnexus/pgae438

  Lipsitch M, Bassett MT, Brownstein JS, Elliott P, Eyre D, Grabowski MK, Hay JA, Johansson MA, Kissler SM, Larremore DB, Layden JE, Lessler J, Lynfield R, MacCannell D, Madoff LC, Metcalf CJE, Meyers LA, Ofori SK, Quinn C, Bento AI, Reich NG, Riley S, Rosenfeld R, Samore MH, Sampath R, Slayton RB, Swerdlow DL, Truelove S, Varma JK, Grad YH. (2024). Infectious disease surveillance needs for the United States: lessons from Covid-19. Front Public Health. Jul 15, 12, 1408193. doi: 10.3389/fpubh.2024.1408193

2023

Cooper, E., Lound, A., Atchison, C. J., Whitaker, M., Eccles, C., Cooke, G. S., Elliott P, Ward, H. (2023). Awareness and perceptions of Long COVID among people in the REACT programme: Early insights from a pilot interview study. PLoS One, 18(1), e0280943. doi:10.1371/journal.pone.0280943

Eales, O., Page, A. J., Tang, S. N., Walters, C. E., Wang, H., Haw, D.,, Trotter, A., Le Viet, L, Foster-Nyarko, E., Prosolek, S., Atchison, C., Ashby, D., Cooke, G., Barclay, W., Donnelly, C., O’Grady, J., Volz, E., Darzi, A., Ward, H., Elliott, P.,  Riley, S. The use of representative community samples to assess SARS-CoV-2 lineage competition: Alpha outcompetes Beta and wild-type in England from January to March 2021. Microbial Genomics. 2023, February, 9(2). doi:10.1099/mgen.0.000887

Atchison, C. J., Whitaker, M., Donnelly, C. A., Chadeau-Hyam, M., Riley, S., Darzi, A., Ashby, D., Barclay, W., Cooke, G.S., Elliott, P., Ward, H. Characteristics and predictors of persistent symptoms post-COVID-19 in children and young people: a large community cross-sectional study in England. Archives Dis Child, March 2023. doi:10.1136/archdischild-2022-325152

Elliott, P., Ward, H., Riley, S. Population Monitoring of SARS-CoV-2 Infections via Random Sampling During the COVID-19 Pandemic. Am J Public Health, 2023; 113(5), 514-516. doi:10.2105/AJPH.2023.307231

Routen, A., O'Mahoney, L., Aiyegbusi, O. L., Alder, Y., Banerjee, A., Buckland, L., Brightling, C., Calvert, M., Camaradou, J., Chaturvedi, N., Chong, A., Dalrymple, E., Eggo, R.M., Elliott, P., Evans, R.A., Gibson, A., Harons, S., Herrett, E., Houchen-Wolloff, L., Hughes, S.E., Jeyes, F., Matthews, K., McMullan, C., Morley, J., Shafran, R., Smith, N., Stanton, D., Stephenson, T., Sterne, J., Turner, G.M., Ward, H., Khunti, K. (2023). Patient and public involvement within epidemiological studies of long COVID in the UK. Nat Med, 29(4), 771-773. doi:10.1038/s41591-023-02251-5

Elliott, P., Whitaker, M., Tang, D., Eales, O., Steyn, N., Bodinier, B., Wang, H., Elliott, J., Atchison, C., Ashby, D., Barclay, W., Taylor, G., Darzi, A., Cooke, G., Darzi, A., Cooke, G.S., Ward, H., Donnelly, C.A., Riley, S., Chadeau-Hyam, M. (2023). Design and Implementation of a National SARS-CoV-2 Monitoring Program in England: REACT-1 Study. Am J Public Health, 113(5), 545-554. doi:10.2105/AJPH.2023.307230

Eales, O., Haw, D., Wang, H., Atchison, C., Ashby, D., Cooke, G. S., Barclay, W., Ward, H., Darzi, A., Donnelly, C.A., Chadeau-Hyam, M., Elliott, P., Riley, S. (2023). Dynamics of SARS-CoV-2 infection hospitalisation and infection fatality ratios over 23 months in England. PLoS Biol, 21(5), e3002118. doi:10.1371/journal.pbio.3002118

Whitaker, M, Davies B, Atchison C, Barclay W, Ashby D, Darzi A, Riley S, Cooke G, Donnelly CA, Chadeau-Hyam M, Elliott P, Ward H. SARS-CoV-2 rapid antibody test results and subsequent risk of hospitalisation and death in 361,801 people. Nat Commun 14, 4957 (2023). https://doi.org/10.1038/s41467-023-40643-w.

Eales, I., de Oliveira, Martins, L., Page, A., Wang, H., Bodinier, B., Tang, D., Haw, D., Jonnerby, L.J.A., Atchison, C., Ashby, D., Barclay, W., Taylor, G., Coke, G., Ward, H., Darzi, A., Riley, S., Elliott, P., Donnelly, C., Chadeau, M. (2023). Dynamics and scale of the SARS-CoV-2 variant Omicron epidemic in England. Nature Comm, 13. doi: 10.1038/s41467-022-32096-4

Ward, H., Atchison, C., Whitaker, M., Davies, B., Ashby, D., Darzi, A., Chadeau-Hyam, M, Riley, S, Donnelly, CA, Barclay W, Cooke, G, Elliott, P. (2023). Design and Implementation of a National Program to Monitor the Prevalence of SARS-CoV-2 IgG Antibodies in England Using Self-Testing: The REACT-2 Study.. Am J Public Health, 113(11), 1201-1209. doi:10.2105/AJPH.2023.307381

Atchison, C. J., Davies, B., Cooper, E., Lound, A., Whitaker, M., Hampshire, A., Azor A, Donnelly, CA, Chadeau-Hyam, M, Cooke, G, Elliott, P. (2023). Long-term health impacts of COVID-19 among 242,712 adults in England. Nat Commun, 14(1), 6588. doi:10.1038/s41467-023-41879-2

2022

Khan, M., Rosadas, C., Katsanovskaja, K., Weber, I. D., Shute, J., Ijaz, S., et al. (2022). Simple, sensitive, specific self-sampling assay secures SARS-CoV-2 antibody signals in sero-prevalence and post-vaccine studies. Scientific Reports, 12(1). doi:10.1038/s41598-022-05640-x.

Chadeau-Hyam, M., Wang, H., Eales, O., Haw, D., Bodinier, B., Whitaker, M., et al. (2022). SARS-CoV-2 infection and vaccine effectiveness in England (REACT-1): a series of cross-sectional random community surveys. Lancet Respiratory Medicine. doi:10.1016/S2213-2600(21)00542-7.

Ward, H., Whitaker, M., Flower, B., Tang, S. N., Atchison, C., Darzi, A., et al. (2022). Population antibody responses following COVID-19 vaccination in 212,102 individuals. Nature Communications, 13(1), 907. doi:10.1038/s41467-022-28527-x.

Eales, O., Walters, C. E., Wang, H., Haw, D., Ainslie, K. E. C., Atchison, C. J., et al. (2022). Characterising the persistence of RT-PCR positivity and incidence in a community survey of SARS-CoV-2. Wellcome Open Research, 7, 102. doi:10.12688/wellcomeopenres.17723.1.

Elliott, P., Bodinier, B., Eales, O., Wang, H., Haw, D., Elliott, J., et al. (2022). Rapid increase in Omicron infections in England during December 2021: REACT-1 study. Science, 375(6587), 1406+. doi:10.1126/science.abn8347.

Rosadas, C., Khan, M., Parker, E., Marchesin, F., Katsanovskaja, K., Sureda-Vives, M., et al. (2022). Detection and quantification of antibody to SARS-CoV-2 receptor binding domain provides enhanced sensitivity, specificity and utility. Journal of Virological Methods, 302. doi:10.1016/j.jviromet.2022.114475.

Whitaker, M., Elliott, J., Chadeau-Hyam, M., Riley, S., Darzi, A., Cooke, G., et al. (2022). Persistent COVID-19 symptoms in a community study of 606,434 people in England. Nature Communications, 13(1). doi:10.1038/s41467-022-29521-z.

Elliott, P., Eales, O., Steyn, N., Tang, D., Bodinier, B., Wang, H., et al. (2022). Twin peaks: The Omicron SARS-CoV-2 BA.1 and BA.2 epidemics in England. Science, eabq4411. doi:10.1126/science.abq4411.

Cann, A., Clarke, C., Brown, J., Thomson, T., Prendecki, M., Moshe, M., et al. (2021). Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody lateral flow assay for antibody prevalence studies following vaccination: a diagnostic accuracy study. Wellcome Open Research, 6, 358. doi:10.12688/wellcomeopenres.17231.2.

Chadeau-Hyam, M., Eales, O., Bodinier, B., Wang, H., Haw, D., Whitaker, M., et al. (2022). Breakthrough SARS-CoV-2 infections in double and triple vaccinated adults and single dose vaccine effectiveness among children in Autumn 2021 in England: REACT-1 study. EClinicalMedicine, 48, 101419. doi:10.1016/j.eclinm.2022.101419.

Wong, N. C. K., Meshkinfamfard, S., Turbé, V., Whitaker, M., Moshe, M., Bardanzellu, A., et al. (2022). Machine learning to support visual auditing of home-based lateral flow immunoassay self-test results for SARS-CoV-2 antibodies. Communications Medicine, 2, 78. doi:10.1038/s43856-022-00146-z.

Eales, O., Page, A. J., Martins, L. D. O., Wang, H., Bodinier, B., Haw, D., et al. (2022). SARS-CoV-2 lineage dynamics in England from September to November 2021: high diversity of Delta sub-lineages and increased transmissibility of AY.4.2. BMC Infectious Diseases, 22(1). doi:10.1186/s12879-022-07628-4.

Eales, O., Martins, L. D. O., Page, A. J., Wang, H., Bodinier, B., Tang, D., et al. (2022). Dynamics of competing SARS-CoV-2 variants during the Omicron epidemic in England. Nature Communications, 13(1). doi:10.1038/s41467-022-32096-4.

Atchison, C. J., Moshe, M., Brown, J. C., Whitaker, M., Wong, N. C. K., Bharath, A. A., et al. (2022). Validity of Self-testing at Home With Rapid Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Antibody Detection by Lateral Flow Immunoassay. Clinical Infectious Diseases. doi:10.1093/cid/ciac629.

Elliott, P., Eales, O., Bodinier, B., Tang, D., Wang, H., Jonnerby, J., et al. (2022). Dynamics of a national Omicron SARS-CoV-2 epidemic during January 2022 in England. Nature Communications, 13(1). doi:10.1038/s41467-022-32121-6.

Eales, O., Ainslie, K. E. C., Walters, C. E., Wang, H., Atchison, C., Ashby, D., et al. (2022). Appropriately smoothing prevalence data to inform estimates of growth rate and reproduction number. Epidemics, 40. doi:10.1016/j.epidem.2022.100604.

Chadeau-Hyam, M., Tang, D., Eales, O., Bodinier, B., Wang, H., Jonnerby, J., et al. (2022). Omicron SARS-CoV-2 epidemic in England during February 2022: A series of cross-sectional community surveys. Lancet Regional Health – Europe, 21, 100462. doi:10.1016/j.lanepe.2022.100462.

Mosscrop, L., Watber, P., Elliott, P., Cooke, G., Barclay, W., Freemont, P. S., et al. (2022). Evaluation of the impact of pre-analytical conditions on sample stability for the detection of SARS-CoV-2 RNA. Journal of Virological Methods, 309. doi:10.1016/j.jviromet.2022.114607.

Whitaker, M., Elliott, J., Bodinier, B., Barclay, W., Ward, H., Cooke, G., et al. (2022). Variant-specific symptoms of COVID-19 in a study of 1,542,510 adults in England. Nature Communications, 13(1), 6856. doi:10.1038/s41467-022-34244-2.

Eales, O., Wang, H., Haw, D., Ainslie, K. E. C., Walters, C. E., Atchison, C., et al. (2022). Trends in SARS-CoV-2 infection prevalence during England's roadmap out of lockdown, January to July 2021. PLOS Computational Biology, 18(11), e1010724. doi:10.1371/journal.pcbi.1010724.

2021

REACT study peer-reviewed publications 2020-2025

2020

Flower B, Brown JC, Simmons B, Moshe M, Frise R, Penn R, Kugathasan R, Petersen C, Daunt A, Ashby D, Riley S, Atchison CJ, Taylor GP, Satkunarajah S, Naar L, Klaber R, Badhan A, Rosadas C, Khan M, Fernandez N, Sureda-Vives M, Cheeseman HM, O'Hara J, Fontana G, Pallett SJC, Rayment M, Jones R, Moore LSP, McClure MO, Cherepanov P, Tedder R, Ashrafian H, Shattock R, Ward H, Darzi A, Elliott P, Barclay WS, Cooke GS. (2020). Clinical and laboratory evaluation of SARS-CoV-2 lateral flow assays for use in a national COVID-19 seroprevalence survey. Thorax, 75(12), 1082–1088. doi:10.1136/thoraxjnl-2020-215732.

Atchison C, Pristerà P, Cooper E, Papageorgiou V, Redd R, Piggin M, Flower B, Fontana G, Satkunarajah S, Ashrafian H, Lawrence-Jones A, Naar L, Chigwende J, Gibbard S, Riley S, Darzi A, Elliott P, Ashby D, Barclay W, Cooke GS, Ward H. (2020). Usability and acceptability of home-based self-testing for SARS-CoV-2 antibodies for population surveillance. Clinical Infectious Diseases. doi:10.1093/cid/ciaa1178.

Riley, S., Atchison, C., Ashby, D., Donnelly, C. A., Barclay, W., Cooke, G., Ward H, Darzi A, Elliott P.; REACT Study Group. (2020). REal-time Assessment of Community Transmission (REACT) of SARS-CoV-2 virus: Study protocol. Wellcome Open Research, 5, 200. doi:10.12688/wellcomeopenres.16228.2.

REACT study scientific reports: non-peer-reviewed

To view all reports see here

REACT Study Investigators, Riley S, Ainslie KEC, Eales O, Walters CE, Wang H, Atchison C, Diggle PJ, Ashby D, Donnelly CA, Cooke G, Barclay W, Ward H, Taylor G, Darzi A, Elliott P. (2020). Community prevalence of SARS-CoV-2 virus in England during May 2020: REACT Study. medRxiv.
This early REACT study estimated how widely COVID-19 was circulating in England after the first wave. It provided one of the first large-scale community snapshots of infection prevalence.

REACT Study Investigators, Riley S, Ainslie KEC, Eales O, Walters CE, Wang H, Atchison C, Fronterre C, Diggle PJ, Ashby D, Donnelly CA, Cooke G, Barclay W, Ward H, Taylor G, Darzi A, Elliott P. (2020). Transient dynamics of SARS-CoV-2 as England exited national lockdown. medRxiv.
This paper examined how infection rates changed as England eased its first national lockdown. It highlighted the fragile balance between reopening and controlling transmission.

REACT Study Investigators, Riley S, Ainslie KEC, Eales O, Walters CE, Wang H, Atchison C, Fronterre C, Diggle PJ, Ashby D, Donnelly CA, Cooke G, Barclay W, Ward H, Taylor G, Darzi A, Elliott P. (2020). Resurgence of SARS-CoV-2 in England: Detection by community antigen surveillance. medRxiv.
The study documented the resurgence of COVID-19 infections in England during late summer 2020. Community surveillance data showed infections were beginning to rise rapidly again.

REACT Study Investigators, Riley S, Ainslie KEC, Eales O, Walters CE, Wang H, Atchison C, Fronterre C, Diggle PJ, Ashby D, Donnelly CA, Cooke G, Barclay W, Ward H, Taylor G, Darzi A, Elliott P. (2020). High prevalence of SARS-CoV-2 swab positivity in England during September 2020: Interim report of Round 5 of REACT-1 Study. medRxiv.
This interim report showed a sharp rise in infections across England during September 2020. It warned of accelerating community transmission before the second wave peaked.

Riley S, Ainslie KEC, Eales O, Walters CE, Wang H, Atchison C, Fronterre C, Diggle PJ, Ashby D, Donnelly CA, Cooke G, Barclay W, Ward H, Taylor G, Darzi A, Elliott P. (2020). High and increasing prevalence of SARS-CoV-2 swab positivity in England: REACT-1 Round 5 Updated Report. medRxiv.
Updated findings confirmed that infection prevalence continued increasing nationwide. The report reinforced concerns about widespread transmission entering autumn 2020.

Ward H, Cooke G, Atchison C, Whitaker M, Elliott J, Moshe M, Flower B, Daunt A, Ainslie K, Ashby D, Donnelly C, Riley S, Darzi A, Barclay W, Elliott P. (2020). Declining prevalence of antibody positivity to SARS-CoV-2: a community study of 365,000 adults. medRxiv.
This antibody study found that detectable antibodies declined over time in the population. The findings raised important questions about the duration of post-infection immunity.

REACT Study Investigators, Riley S, Ainslie KEC, Eales O, Walters CE, Wang H, Atchison C, Fronterre C, Diggle PJ, Ashby D, Donnelly CA, Cooke G, Barclay W, Ward H, Taylor G, Darzi A, Elliott P. (2020). High prevalence of SARS-CoV-2 swab positivity and increasing R number in England during October 2020: REACT-1 Round 6 Interim Report. Imperial College London.
The report showed infections and transmission rates continued climbing in October 2020. It provided evidence supporting tighter public health restrictions.

Riley S, Ainslie KEC, Eales O, Walters CE, Wang H, Atchison C, Fronterre C, Diggle PJ, Ashby D, Donnelly CA, Cooke G, Barclay W, Ward H, Taylor G, Darzi A, Elliott P. REACT-1 Round 6 Updated Report: High prevalence of SARS-CoV-2 swab positivity with reduced rate of growth in England at the start of November 2020. MedRxiv, November 20, 2020.
Although infections remained high, the growth rate appeared to slow in early November. The findings suggested interventions might have begun reducing transmission.

Riley S, Ainslie KEC, Eales O, Walters CE, Wang H, Atchison C, Fronterre C, Diggle PJ, Ashby D, Donnelly CA, Cooke G, Barclay W, Ward H, Taylor G, Darzi A, Elliott P. REACT Round 7 Interim Report: Fall in prevalence of SARS-CoV-2 swab positivity in England during national lockdown. MedRxiv, December 2, 2020.
This report found that England’s second national lockdown reduced infection prevalence. Declines were observed across many regions and age groups.

Riley S, Ainslie KEC, Eales O, Walters CE, Wang H, Atchison C, Fronterre C, Diggle PJ, Ashby D, Donnelly CA, Cooke G, Barclay W, Ward H, Taylor G, Darzi A, Elliott P. REACT Round 7 Updated Report: Regional heterogeneity in changes in prevalence of SARS-CoV-2 infections during the second National COVID-19 Lockdown in England. MedRxiv, December 16, 2020.
The study highlighted regional differences in how infections changed during lockdown. Some areas improved rapidly while others saw slower declines.

Riley S, Wang H, Eales O, Walters CE, Atchison C, Fronterre C, Diggle PJ, Ashby D, Donnelly CA, Cooke G, Barclay W, Ward H, Taylor G, Darzi A, Elliott P. REACT Round 8 Interim Report: SARS-CoV-2 prevalence during the initial stages of the third national lockdown in England. MedRxiv, January 22, 2021.
This interim report showed infections remained extremely high at the beginning of England’s third lockdown. It reflected the severe winter wave of COVID-19.

Riley S, Ainslie KEC, Eales O, Walters CE, Wang H, Atchison C, Fronterre C, Diggle PJ, Ashby D, Donnelly CA, Cooke G, Barclay W, Ward H, Taylor G, Darzi A, Elliott P. REACT Round 8 Final Report: High average prevalence with regional heterogeneity of trends in SARS-CoV-2 infections in the community in England during January 2021. MedRxiv, January 31, 2021.
The final Round 8 report confirmed sustained high infection prevalence across England. It also showed substantial variation between regions.

Riley S, Walters CE, Wang H, Eales O, Haw D, Ainslie KEC, Atchison C, Fronterre C, Diggle PJ, Ashby D, Donnelly CA, Cooke G, Barclay W, Ward H, Darzi A, Elliott P. REACT-1 round 9 interim report: Downward trend of SARS-CoV-2 in England in February 2021 but still at high prevalence. MedRxiv, February 23, 2021.
This study showed infections were falling during February 2021. However, prevalence remained high enough to sustain continued concern.

Riley S, Wang H, Eales O, Haw D, Walters CE, Ainslie KEC, Atchison C, Fronterre C, Diggle PJ, Ashby D, Donnelly CA, Cooke G, Barclay W, Ward H, Darzi A, Elliott P. REACT-1 round 9 final report: Continued but slowing decline of prevalence of SARS-CoV-2 during national lockdown in England in February 2021. MedRxiv, March 6, 2021.
The report confirmed infections continued decreasing during lockdown, though the pace of decline was slowing. It informed debates about reopening restrictions.

Riley S, Eales O, Haw D, Walters CE, Wang H, Ainslie KEC, Atchison C, Fronterre C, Diggle PJ, Ashby D, Donnelly CA, Cooke G, Barclay W, Ward H, Darzi A, Elliott P. REACT-1 round 10 report: Level prevalence of SARS-CoV-2 swab-positivity in England during third national lockdown in March 2021. MedRxiv, April 15, 2021.
This paper suggested infection rates had plateaued during March 2021. It indicated that reductions in transmission were beginning to level off.

Elliott J, Whitaker M, Bodinier B, Riley S, Ward H, Cooke G, Darzi A, Chadeau-Hyam M, Elliott P. Symptom reporting in over 1 million people: community detection of COVID-19. MedRxiv, February 12, 2021.
This large community study evaluated how symptom reporting could help detect COVID-19 cases. It identified symptom patterns most predictive of infection.

Ward H, Cooke G, Whitaker M, Redd R, Eales O, Brown JC, Collet K, Cooper E, Daunt A, Jones K, Moshe M, Willicombe M, Day S, Atchison C, Darzi A, Donnelly CA, Riley S, Ashby D, Barclay WS, Elliott P. REACT-2 round 5: Increasing prevalence of SARS-CoV-2 antibodies demonstrate impact of the second wave and of vaccine roll-out in England. MedRxiv, March 1, 2021.
This antibody surveillance study showed rising immunity levels in England due to both second-wave infections and the early vaccine rollout. It provided evidence of the growing population-level immune response.

Riley S, Haw D, Walters C, Wang H, Eales O, Ainslie K, Atchison C, Fronterre C, Diggle P, Page A, Trotter A, Viet TL, Nabil-Fareed A, O'Grady J, The COVID-19 Genomics UK Consortium, Ashby D, Donnelly C, Cooke G, Barclay W, Ward H, Darzi A, Elliott P. REACT-1 round 11 report: low prevalence of SARS-CoV-2 infection in the community prior to the third step of the English roadmap out of lockdown. MedRxiv, May 17, 2021.
This report found low levels of community infection before further easing of restrictions in England. It suggested lockdown measures and vaccination were helping suppress transmission.

Eales O, Page AJ, Tang S, Walters C, Wang H, Haw D, Trotter AJ, Viet TL, Foster-Nyarko E, Prosolek S, Atchison C, Ashby D, Cooke G, Barclay W, Donnelly C, O'Grady J, Volz E, The COVID-19 Genomics UK Consortium, Darzi A, Ward H, Elliott P, Riley S. SARS-CoV-2 lineage dynamics in England from January to March 2021 inferred from representative community samples. MedRxiv, May 14, 2021.
This genomic analysis tracked how different COVID-19 variants spread in England during early 2021. It highlighted changing lineage patterns before Delta became dominant.

Davies B, Araghi M, Moshe M, Gao H, Bennet K, Jenkins J, Atchison C, Darzi A, Ashby D, Riley S, Barclay W, Elliott P, Ward H, Cooke G. Acceptability, usability and performance of lateral flow immunoassay tests for SARS-CoV-2 antibodies: REACT-2 study of self-testing in non-healthcare key workers. MedRxiv, June 27, 2021.
This study evaluated whether people could successfully self-administer antibody tests at home. Results suggested self-testing was practical and reasonably accurate.

Riley S, Wang H, Eales O, Haw D, Walters C, Ainslie K, Atchison C, Fronterre C, Diggle P, Page A, Prosolek S, Trotter AJ, Le Viet T, Alikhan N-F, The COVID-19 Genomics UK Consortium COG-UK, Ashby D, Donnelly C, Cooke G, Barclay W, Ward H, Darzi A, Elliott P. REACT-1 round 12 report: resurgence of SARS-CoV-2 infections in England associated with increased frequency of the Delta variant. MedRxiv, June 21, 2021.
This paper documented the rapid resurgence of infections linked to the Delta variant. It showed how quickly Delta displaced earlier variants in England.

Whitaker M, Elliott J, Chadeau-Hyam M, Riley S, Darzi A, Cooke G, Ward H, Elliott P. Persistent symptoms following SARS-CoV-2 infection in a random community sample of 508,707 people. MedRxiv, July 3, 2021.
This large population study examined long-lasting symptoms after COVID-19 infection. It contributed important evidence about the scale and burden of Long Covid.

Riley S, Eales O, Haw D, Wang H, Walters C, Ainslie K, Christina A, Fronterre C, Diggle P, Ashby D, Donnelly C, Barclay W, Cooke G, Ward H, Darzi A, Elliott P. REACT-1 round 13 interim report: acceleration of SARS-CoV-2 Delta epidemic in the community in England during late June and early July 2021. MedRxiv, July 8, 2021.
This interim analysis showed rapid acceleration of Delta-driven infections in England. It highlighted increasing transmission despite vaccination progress.

Cann A, Clarke C, Brown J, Thomson T, Prendecki M, Moshe M, Badhan A, Elliott P, Darzi A, Riley S, Ashby D, Willicombe M, Kelleher P, Randell P, Ward H, Barclay W, Cooke G. SARS-CoV-2 Antibody Lateral Flow Assay for antibody prevalence studies following vaccine roll out: a Diagnostic Accuracy Study. MedRxiv, July 16, 2021.
This diagnostic study assessed the accuracy of antibody lateral flow tests after vaccination. It supported the use of rapid antibody testing in surveillance studies.

Ward H, Whitaker M, Tang S, Atchison C, Darzi A, Donnelly C, Diggle P, Ashby D, Riley S, Barclay W, Elliott P, Cooke G. Vaccine uptake and SARS-CoV-2 antibody prevalence among 207,337 adults during May 2021 in England: REACT-2 study. MedRxiv, July 18, 2021.
This study measured vaccine uptake and antibody prevalence across England. It identified demographic differences in vaccination and immune response.

Ward H, Atchison C, Whitaker M, Donnelly C, Riley S, Ashby D, Darzi A, Barclay W, Cooke G, Elliott P; for the REACT study team. Increasing SARS-CoV-2 antibody prevalence in England at the start of the second wave: REACT-2 Round 4 cross-sectional study in 160,000 adults. MedRxiv, July 22, 2021.
This cross-sectional study showed antibody prevalence increasing as England entered the second wave. It reflected both prior infections and expanding immunity.

Eales O, Walters CE, Wang H, Haw D, Ainslie KEC, Atchison C, Page AJ, Prosolek SJ, Trotter AJ, Le Viet T, Alikhan N-F, Jackson LM, Ludden C, The COVID-19 Genomics UK (COG-UK) Consortium, Ashby D, Donnelly CA, Cooke G, Barclay W, Ward H, Darzi A, Elliott P, Riley S. Characterising the persistence of RT-PCR positivity and incidence in a community survey of SARS-CoV-2. MedRxiv, August 13, 2021.
The paper examined how long infected individuals remained PCR-positive. It improved understanding of infection duration and interpretation of testing data.

Elliott P, Haw D, Wang H, Eales O, Walters C, Ainslie K, Atchison C, Fronterre C, Diggle P, Page A, Trotter A, Prosolek S, COG-UK TCGUKC, Ashby D, Donnelly C, Barclay W, Cooke G, Ward H, Darzi A, Riley S. REACT-1 round 13 final report: exponential growth, high prevalence of SARS-CoV-2 and vaccine effectiveness associated with Delta variant in England during May to July 2021. MedRxiv, September 10, 2021.
This report described rapid Delta-driven growth alongside analysis of vaccine effectiveness. It showed vaccines reduced risk but did not fully prevent infection.

Chadeau-Hyam M, Wang H, Eales O, Haw D, Bodinier B, Whitaker M, Walters CE, Ainslie KEC, Atchison C, Fronterre C, Diggle PJ, Page AJ, Trotter AJ, The COVID-19 Genomics UK (COG-UK) Consortium, Ashby D, Barclay W, Taylor G, Cooke G, Ward H, Darzi A, Riley S, Donnelly CA, Elliott P. REACT-1 study round 14: High and increasing prevalence of SARS-CoV-2 infection among school-aged children during September 2021 and vaccine effectiveness against infection in England. MedRxiv, October 22, 2021.
This study found particularly high infection rates among school-aged children in autumn 2021. It also provided updated estimates of vaccine effectiveness.

Chadeau-Hyam M, Eales O, Bodinier B, Wang H, Haw D, Whitaker M, Walters CE, Atchison C, Diggle PJ, Page AJ, Ashby D, Barclay W, Taylor G, Cooke G, Ward H, Darzi A, Riley S, Donnelly CA, Elliott P. REACT-1 round 15 interim report: High and rising prevalence of SARS-CoV-2 infection in England from end of September 2021 followed by a fall in late October 2021. MedRxiv, November 3, 2021.
This interim report identified very high infection prevalence in autumn 2021 before a subsequent decline. It reflected changing epidemic dynamics entering winter.

Chadeau-Hyam M, Eales O, Bodinier B, Wang H, Haw D, Whitaker M, Walters C, Jonnerby J, Atchison C, Diggle P, Page A, Ashby D, Barclay W, Taylor G, Cooke G, Ward H, Darzi A, Donnelly C, Elliott P. Spiral: REACT-1 round 15 final report: Increased breakthrough SARS-CoV-2 infections among adults who had received two doses of vaccine, but booster doses and first doses in children are providing important protection. Imperial College London, November 18, 2021.
The report showed breakthrough infections increasing among fully vaccinated adults. However, booster doses and vaccination in children provided important additional protection.

Elliott P, Bodinier B, Eales O, Wang H, Haw D, Elliott J, Whitaker M, Jonnerby J, Tang D, Walters C, Atchison C, Diggle P, Page A, Trotter A, Ashby D, Barclay W, Taylor G, Ward H, Darzi A, Cooke G, Chadeau-Hyam M, Donnelly C. Rapid increase in Omicron infections in England during December 2021: REACT-1 study. MedRxiv, December 24, 2021.
This paper documented the explosive spread of the Omicron variant in England. It provided some of the earliest large-scale evidence of Omicron’s transmission advantage.

Elliott P, Eales O, Bodinier B, Tang D, Wang H, Jonnerby J, Haw D, Elliott J, Whitaker M, Walters C, Atchison C, Diggle P, Page A, Trotter A, Ashby D, Barclay W, Taylor G, Ward H, Darzi A, Cooke G, Chadeau-Hyam M, Donnelly C. Spiral: Post-peak dynamics of a national Omicron SARS-CoV-2 epidemic during January 2022. Imperial College London, January 25, 2022.
This report examined how Omicron infections evolved after the initial peak. It highlighted continuing high prevalence despite declining case numbers.

Eales O, Ainslie KEC, Walters CE, Wang H, Atchison C, Ashby D, Donnelly CA, Cooke G, Barclay W, Ward H, Darzi A, Elliott P, Riley S. Appropriately smoothing prevalence data to inform estimates of growth rate and reproduction number. MedRxiv, 2022.
This methodological paper explored statistical approaches for estimating epidemic growth rates. It aimed to improve interpretation of noisy surveillance data.

Elliott P, Eales O, Bodinier B, Tang D, Wang H, Jonnerby J, Haw D, Elliott J, Whitaker M, Walters CE, Atchinson C, Diggle PJ, Page AJ, Trotter A, Ashby D, Barclay W, Taylor G, Ward H, Darzi A, Cooke G, Chadeau-Hyam M, Donnelly CA. Post-peak dynamics of a national Omicron SARS-CoV-2 epidemic during January 2022. MedRxiv, 2022.
This study analysed infection trends after the Omicron peak in England. It provided insight into how rapidly Omicron spread and receded.

Chadeau-Hyam M, Tang D, Eales O, Bodinier B, Wang H, Jonnerby J, Whitaker M, Elliott J, Haw D, Walters CE, Atchison C, Diggle PJ, Page AJ, Ashby D, Barclay W, Taylor G, Cooke G, Ward H, Darzi A, Donnelly CA, Elliott P. The Omicron SARS-CoV-2 epidemic in England during February 2022. MedRxiv, March 13, 2022.
This report described the ongoing Omicron epidemic in England during February 2022. It showed sustained transmission despite widespread immunity.

Elliott P, Eales O, Steyn N, Tang D, Bodinier B, Wang H, Elliott J, Whitaker M, Atchison C, Diggle P, Trotter A, Ashby D, Barclay W, Taylor G, Ward H, Darzi A, Cooke G, Donnelly C, Chadeau-Hyam M. Twin peaks: the Omicron SARS-CoV-2 BA.1 and BA.2 epidemics in England. Imperial College London, 2022.
This analysis compared the overlapping BA.1 and BA.2 Omicron waves in England. It demonstrated how BA.2 rapidly replaced BA.1.

Eales O, de Oliveira Martins L, Page AJ, Wang H, Bodinier B, Tang D, Haw D, Jonnerby J, Atchison C, Ashby D, Barclay W, Taylor G, Cooke G, Ward H, Darzi A, Riley S, Elliott P, Donnelly CA, Chadeau-Hyam M. The new normal? Dynamics and scale of the SARS-CoV-2 variant Omicron epidemic in England. MedRxiv, 2022.
This study explored how Omicron reshaped COVID-19 transmission patterns in England. It suggested persistently high circulation might become the “new normal.”

Whitaker M, Elliott J, Bodinier B, Barclay W, Ward H, Cooke G, Donnelly CA, Chadeau-Hyam M, Elliott P. Variant-specific symptoms of COVID-19 among 1,542,510 people in England. MedRxiv, May 23, 2022.
This large study compared symptoms linked to different COVID-19 variants. It found symptom profiles changed significantly between variants such as Delta and Omicron.

Eales O, Wang H, Haw D, Ainslie K, Walters C, Atchison C, Cooke G, Barclay W, Ward H, Darzi A, Ashby D, Donnelly CA, Elliott P, Riley S. Trends in SARS-CoV-2 infection prevalence during England’s roadmap out of lockdown, January to July 2021. MedRxiv, 2022.
This paper analysed infection trends as England gradually lifted COVID-19 restrictions. It documented how reopening influenced transmission patterns.

Atchison C, Moshe M, Brown J, Whitaker M, Wong N, Bharath A, McKendry RA, Darzi A, Ashby D, Donnelly CA, Riley S, Elliott P, Barclay WS, Cookee GS, Ward H. Validity of self-testing at home with rapid SARS-CoV-2 antibody detection by lateral flow immunoassay. MedRxiv, 2022.
This study evaluated how accurately people could perform rapid antibody tests at home. It supported the feasibility of large-scale self-testing programmes.

Cooper E, Lound A, Jones K, Bruton J, Day S, Atchison CJ, Eccles C, Piper A, Cooke GS, Chadeau-Hyam M, Elliott P, Ward H. Recognition, support and self-management in Long Covid: a population-based qualitative study. MedRxiv, 2025.
This qualitative study explored how people with Long Covid experience recognition, healthcare support, and self-management. It highlighted ongoing challenges faced by patients.

Steyn N, Chadeau-Hyam M, Whitaker M, Atchison C, Ashby D, Cooke GS, Ward H, Elliott P, Donnelly CA. Pandemic-risk-related behaviour change in England from June 2020 to March 2022: REACT-1 study among over 2 million people. MedRxiv, 2025.
This study analysed how public behaviours changed throughout the pandemic in England. It linked behavioural shifts to perceived risk and changing epidemic conditions.

External articles using REACT data

Pourmalek F. CovidVisualized: Visualized compilation of international updated models’ estimates of COVID-19 pandemic at global and country levels. BMC Research Notes. 2022 Apr 9;15(1).
This paper introduced a visual platform compiling international COVID-19 model estimates. It aimed to improve accessibility and comparison of pandemic forecasts across countries.

Bajaj S, Chen S, Creswell R, Naidoo R, Tsui JL-H, Kolade O, et al. COVID-19 testing and reporting behaviours in England across different sociodemographic groups: a population-based study using testing data and data from community prevalence surveillance surveys. The Lancet Digital Health. 2024 Nov;6(11):e778–90.
This study examined differences in COVID-19 testing and reporting behaviours across social and demographic groups in England. It highlighted inequalities affecting surveillance data accuracy.

Nicholson G, Lehmann B, Padellini T, Pouwels KB, Jersakova R, Lomax J, King RE, Mallon AM, Diggle PJ, Richardson S, Blangiardo M, Holmes C. Improving local prevalence estimates of SARS-CoV-2 infections using a causal debiasing framework. Nature Microbiology. 2022 Jan;7(1):97–107.
The authors developed a statistical framework to reduce bias in local COVID-19 prevalence estimates. The method improved the reliability of infection surveillance data.

Li G, Denise H, Diggle P, Grimsley J, Holmes C, James D, Jersakova R, Mole C, Nicholson G, Smith CR, Richardson S, Rowe W, Rowlingson B, Torabi F, Wade MJ, Blangiardo M. A spatio-temporal framework for modelling wastewater concentration during the COVID-19 pandemic. Environment International. 2023 Feb;172:107765.
This paper proposed a framework for modelling SARS-CoV-2 concentrations in wastewater over time and geography. It demonstrated how wastewater data can strengthen public health surveillance.

Nicholson G, Blangiardo M, Briers M, Diggle PJ, Fjelde TE, Ge H, Goudie RJB, Jersakova R, King RE, Lehmann BCL, Mallon AM, Padellini T, Teh YW, Holmes C, Richardson S. Interoperability of statistical models in pandemic preparedness: principles and reality. Statistical Science. 2022 May;37(2):183–206.
The article discussed how statistical models can be designed to work together during public health emergencies. It identified practical barriers and principles for improving pandemic preparedness.

Budd J, Baker K, Karoune E, Coppock H, Patel S, Payne R, Tendero Cañadas A, Titcomb A, Hurley D, Egglestone S, Butler L, Mellor J, Nicholson G, Kiskin I, Koutra V, Jersakova R, McKendry RA, Diggle P, Richardson S, Schuller BW, Gilmour S, Pigoli D, Roberts S, Packham J, Thornley T, Holmes C. A large-scale and PCR-referenced vocal audio dataset for COVID-19. Scientific Data. 2024 Jun 27;11(1):700.
This study introduced a large audio dataset linked to PCR-confirmed COVID-19 results. It supports research into voice-based disease detection technologies.

Padellini T, Jersakova R, Diggle PJ, Holmes C, King RE, Lehmann BCL, Mallon AM, Nicholson G, Richardson S, Blangiardo M. Time varying association between deprivation, ethnicity and SARS-CoV-2 infections in England: A population-based ecological study. Lancet Regional Health – Europe. 2022 Apr;15:100322.
This ecological study explored how deprivation and ethnicity influenced infection risk over time. It showed that inequalities in COVID-19 burden shifted during the pandemic.

Li G, Diggle P, Blangiardo M. Integrating wastewater and randomised prevalence survey data for national COVID surveillance. Scientific Reports. 2024 Mar 1;14(1):5124.
The paper combined wastewater monitoring with survey-based prevalence data to improve national surveillance. It demonstrated the value of integrating multiple data sources.

Torabi F, Li G, Mole C, Nicholson G, Rowlingson B, Smith CR, Jersakova R, Diggle PJ, Blangiardo M. Wastewater-based surveillance models for COVID-19: A focused review on spatio-temporal models. Heliyon. 2023 Nov 8;9(11):e21734.
This review summarised modelling approaches used in wastewater-based COVID-19 surveillance. It focused particularly on spatial and temporal analytical methods.

Pigoli D, Baker K, Budd J, Butler L, Coppock H, Egglestone S, et al. Assessing the Performance of Machine Learning Methods Trained on Public Health Observational Data: A Case Study From COVID‐19. Statistics in Medicine. 2024 Sep 5;43(25):4861–71.
This paper evaluated machine learning approaches trained on observational public health data. Using COVID-19 as a case study, it assessed strengths and limitations of predictive methods.

Davies NG et al. Association of tiered restrictions and a second lockdown with COVID-19 deaths and hospital admissions in England: a modelling study. The Lancet Infectious Diseases. 2021;21(4):482–492.
This modelling study estimated the impact of regional restrictions and lockdowns on COVID-19 outcomes in England. It found stronger measures substantially reduced hospitalisations and deaths.

Varsavsky T et al. Detecting COVID-19 infection hotspots in England using large-scale self-reported data from a mobile application: a prospective, observational study. The Lancet Public Health. 2021;6(1):e21–e29.
This study used symptom data from a mobile app to identify emerging COVID-19 hotspots. It demonstrated the usefulness of digital self-reporting for rapid surveillance.

Oran DP, Topol EJ. The proportion of SARS-CoV-2 infections that are asymptomatic. Annals of Internal Medicine. 2021 Jan 22;174(5).
This influential review estimated how many COVID-19 infections occur without symptoms. It highlighted the major role of asymptomatic transmission in the pandemic.

Avila-Ponce de León U, Avila-Vales E, Huang K. Modeling the Transmission of the SARS-CoV-2 Delta Variant in a Partially Vaccinated Population. Viruses. 2022 Jan 16;14(1):158.
The study modelled how the Delta variant spreads in populations with partial vaccine coverage. It showed how vaccination levels influence epidemic dynamics.

Maishman T, Schaap S, Silk DS, Nevitt SJ, Woods DC, Bowman VE. Statistical methods used to combine the effective reproduction number, R(t), and other related measures of COVID-19 in the UK. Statistical Methods in Medical Research. 2022 Jul 3;31(9):1757–77.
This paper reviewed methods used to estimate and combine COVID-19 reproduction numbers in the UK. It assessed approaches used for epidemic monitoring and policy advice.

Hill EM, Atkins BD, Keeling MJ, Dyson L, Tildesley MJ. A network modelling approach to assess non-pharmaceutical disease controls in a worker population: An application to SARS-CoV-2. PLOS Computational Biology. 2021 Jun 16;17(6):e1009058.
This modelling study assessed workplace interventions such as distancing and isolation policies. It showed how non-pharmaceutical controls can reduce transmission in worker populations.

Articles using REACT methods/tools

Pearce FA, Lim SH, Bythell M, Lanyon P, Hogg R, Taylor A, Powter G, Cooke GS, Ward H, Chilcot J, Thomas H, Mumford L, McAdoo SP, Pettigrew GJ, Lightstone L, Willicombe M. Antibody prevalence after 3 or more COVID-19 vaccine doses in 23,000 immunosuppressed individuals: a cross-sectional study from MELODY. The Lancet Rheumatology. 2023;5(8):E461–E473. Published August 2023.
This large cross-sectional study examined antibody responses after multiple COVID-19 vaccine doses in immunosuppressed individuals. It showed that many patients developed antibodies after repeated vaccination, though responses varied across conditions and treatments