Imperial College London

DrChristinaAtchison

Faculty of MedicineSchool of Public Health

Principal Clinical Academic Fellow
 
 
 
//

Contact

 

christina.atchison11

 
 
//

Location

 

Reynolds BuildingCharing Cross Campus

//

Summary

 

Publications

Publication Type
Year
to

76 results found

Udeh-Momoh C, Watermeyer T, Sindi S, Giannakopoulou P, Robb C, Ahmadi Abhari S, Zheng B, Waheed A, McKeand E, Salman D, Beaney T, Loots C, Price G, Atchison C, Car J, Majeed A, McGregor A, Kivipelto M, Ward H, Middleton Let al., 2021, Health, lifestyle and psycho-social determinants of poor sleep quality during the Early Phase of the COVID-19 pandemic: a focus on UK older adults deemed clinically extremely vulnerable, Frontiers in Public Health, ISSN: 2296-2565

Journal article

Eales O, Walters C, Wang H, Haw D, Ainslie K, Atchison C, Page A, Prosolek S, Trotter A, Viet TL, Alikhan N-F, Jackson LM, Ludden C, COG UK TCGUKC, Ashby D, Donnelly C, Cooke G, Barclay W, Ward H, Darzi A, Elliott P, Riley Set al., 2021, Characterising the persistence of RT-PCR positivity and incidence in a community survey of SARS-CoV-2

BackgroundCommunity surveys of SARS-CoV-2 RT-PCR swab-positivity provide prevalence estimates largely unaffected by biases from who presents for routine case testing. The REal-time Assessment of Community Transmission-1 (REACT-1) has estimated swab-positivity approximately monthly since May 2020 in England from RT-PCR testing of self-administeredthroat and nose swabs in random non-overlapping cross-sectional community samples. Estimating infection incidence from swab-positivity requires an understanding of the persistence of RT-PCR swab positivity in the community.MethodsDuring round 8 of REACT-1 from 6 January to 22 January 2021, of the 2,282 participants who tested RT-PCR positive, we recruited 896 (39%) from whom we collected up to two additional swabs for RT-PCR approximately 6 and 9 days after the initial swab. We estimated sensitivity and duration of positivity using an exponential model of positivity decay, for all participants and for subsets by initial N-gene cycle threshold (Ct) value, symptom status, lineage and age. Estimates of infection incidence were obtained for the entire duration of the REACT-1 study using P-splines.ResultsWe estimated the overall sensitivity of REACT-1 to detect virus on a single swab as 0.79 (0.77, 0.81) and median duration of positivity following a positive test as 9.7 (8.9, 10.6) days. We found greater median duration of positivity where there was a low N-gene Ct value, in those exhibiting symptoms, or for infection with the Alpha variant. The estimated proportionof positive individuals detected on first swab, was found to be higher 𝑃 for those with an 0 initially low N-gene Ct value and those who were pre-symptomatic. When compared to swab-positivity, estimates of infection incidence over the duration of REACT-1 included sharper features with evident transient increases around the time of key changes in socialdistancing measures.DiscussionHome self-swabbing for RT-PCR based on a single swab, as implemented in REACT-1, has hig

Working paper

Redd R, Cooper E, Atchison C, Pereira I, Hollings P, Cooper T, Millar C, Ashby D, Riley S, Darzi A, Barclay W, Cooke GS, Elliott P, Donnelly CA, Ward Het al., 2021, Behavioural responses to SARS-CoV-2 antibody testing in England: REACT-2 study, Wellcome Open Research, Vol: 6, Pages: 203-203

<ns3:p><ns3:bold>Background:  </ns3:bold>This study assesses the behavioural responses to SARS-CoV-2 antibody test results as part of the REal-time Assessment of Community Transmission-2 (REACT-2) research programme, a large community-based surveillance study of antibody prevalence in England.</ns3:p><ns3:p> <ns3:bold>Methods:</ns3:bold> A follow-up survey was conducted six weeks after the SARS-CoV-2 antibody test. The follow-up survey included 4500 people with a positive result and 4039 with a negative result. Reported changes in behaviour were assessed using difference-in-differences models. A nested interview study was conducted with 40 people to explore how they thought through their behavioural decisions.</ns3:p><ns3:p> <ns3:bold>Results:</ns3:bold> While respondents reduced their protective behaviours over the six weeks, we did not find evidence that positive test results changed participant behaviour trajectories in relation to the number of contacts the respondents had, for leaving the house to go to work, or for leaving the house to socialise in a personal place. The qualitative findings supported these results. Most people did not think that they had changed their behaviours because of their test results, however they did allude to some changes in their attitudes and perceptions around risk, susceptibility, and potential severity of symptoms.</ns3:p><ns3:p> <ns3:bold>Conclusions: </ns3:bold>We found limited evidence that knowing your antibody status leads to behaviour change in the context of a research study. While this finding should not be generalised to widespread self-testing in other contexts, it is reassuring given the importance of large prevalence studies, and the practicalities of doing these at scale using self-testing with lateral flow immunoassay (LFIA).</ns3:p>

Journal article

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 Set al., 2021, 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

BackgroundThe prevalence of SARS-CoV-2 infection continues to drive rates of illness andhospitalisations despite high levels of vaccination, with the proportion of cases caused by theDelta lineage increasing in many populations. As vaccination programs roll out globally andsocial distancing is relaxed, future SARS-CoV-2 trends are uncertain.MethodsWe analysed prevalence trends and their drivers using reverse transcription-polymerasechain reaction (RT-PCR) swab-positivity data from round 12 (between 20 May and 7 June2021) and round 13 (between 24 June and 12 July 2021) of the REal-time Assessment ofCommunity Transmission-1 (REACT-1) study, with swabs sent to non-overlapping randomsamples of the population ages 5 years and over in England.ResultsWe observed sustained exponential growth with an average doubling time in round 13 of 25days (lower Credible Interval of 15 days) and an increase in average prevalence from 0.15%(0.12%, 0.18%) in round 12 to 0.63% (0.57%, 0.18%) in round 13. The rapid growth acrossand within rounds appears to have been driven by complete replacement of Alpha variant byDelta, and by the high prevalence in younger less-vaccinated age groups, with a nine-foldincrease between rounds 12 and 13 among those aged 13 to 17 years. Prevalence amongthose who reported being unvaccinated was three-fold higher than those who reported beingfully vaccinated. However, in round 13, 44% of infections occurred in fully vaccinatedindividuals, reflecting imperfect vaccine effectiveness against infection despite high overalllevels of vaccination. Using self-reported vaccination status, we estimated adjusted vaccineeffectiveness against infection in round 13 of 49% (22%, 67%) among participants aged 18to 64 years, which rose to 58% (33%, 73%) when considering only strong positives (Cyclethreshold [Ct] values < 27); also, we estimated adjusted vaccine effectiveness againstsymptomatic infection of 59% (23%, 78%), with any one of three common COVID-19symptoms reported

Working paper

Ward H, Atchison C, Whitaker M, Donnelly CA, Riley S, Ashby D, Darzi A, Barclay WS, Cooke G, Elliott Pet al., 2021, 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

<jats:title>Abstract</jats:title><jats:sec><jats:title>Background</jats:title><jats:p>REACT-2 Study 5 is a population survey of the prevalence of SARS-CoV-2 antibodies in the community in England.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>We contacted a random sample of the population by sending a letter to named individuals aged 18 or over from the NHS GP registrations list. We then sent respondents a lateral flow immunoassay (LFIA) kit for SARS-CoV-2 antibody self-testing and asked them to perform the test at home and complete a questionnaire, including reporting of their test result. Overall, 161,537 adults completed questionnaires and self-administered LFIA tests for IgG against SARS-CoV-2 between 27 October and 10 November 2020.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>The overall adjusted and weighted prevalence was 5.6% (95% CI 5.4-5.7). This was an increase from 4.4% (4.3-4.5) in round 3 (September), a relative increase of 26.9% (24.0-29.9).The largest increase by age was in the 18 to 24 year old age group, which increased (adjusted and weighted) from 6.7% (6.3-7.2) to 9.9% (9.3-10.4), and in students, (adjusted, unweighted) from 5.9% (4.8-7.1) to 12.1% (10.8-13.5). Prevalence increased most in Yorkshire and The Humber, from 3.4% (3.0-3.8) to 6.3% (5.9-6.8) and the North West from 4.5% (4.2-4.9) to 7.7% (7.2-8.1). In contrast, the prevalence in London was stable, at 9.5% (9.0-9.9) and 9.5% (9.1-10.0) in rounds 3 and 4 respectively. We found the highest prevalence in people of Bangladeshi 15.1% (10.9-20.5), Pakistani 13.9% (11.2-17.2) and African 13.5% (10.7-16.8) ethnicity, and lowest in those of white British ethnicity at 4.2% (4.0-4.3).</jats:p></jats:sec><jats:sec><jats:title>Interpretation</jats:title><jats:p>The second wave of infection in England is apparen

Journal article

Ward H, Whitaker M, Tang SN, Atchison C, Darzi A, Donnelly C, Diggle P, Ashby D, Riley S, Barclay W, Elliott P, Cooke Get al., 2021, Vaccine uptake and SARS-CoV-2 antibody prevalence among 207,337 adults during May 2021 in England: REACT-2 study

Background The programme to vaccinate adults in England has been rapidly implementedsince it began in December 2020. The community prevalence of SARS-CoV-2 anti-spikeprotein antibodies provides an estimate of total cumulative response to natural infection andvaccination. We describe the distribution of SARS-CoV-2 IgG antibodies in adults inEngland in May 2021 at a time when approximately 7 in 10 adults had received at least onedose of vaccine.Methods Sixth round of REACT-2 (REal-time Assessment of Community Transmission-2),a cross-sectional random community survey of adults in England, from 12 to 25 May 2021;207,337 participants completed questionnaires and self-administered a lateral flowimmunoassay test producing a positive or negative result.Results Vaccine coverage with one or more doses, weighted to the adult population inEngland, was 72.9% (95% confidence interval 72.7-73.0), varying by age from 25.1% (24.5-25.6) of those aged 18 to 24 years, to 99.2% (99.1-99.3) of those 75 years and older. Inadjusted models, odds of vaccination were lower in men (odds ratio [OR] 0.89 [0.85-0.94])than women, and in people of Black (0.41 [0.34-0.49]) compared to white ethnicity. Therewas higher vaccine coverage in the least deprived and highest income households. Peoplewho reported a history of COVID-19 were less likely to be vaccinated (OR 0.61 [0.55-0.67]).There was high coverage among health workers (OR 9.84 [8.79-11.02] and care workers (OR4.17 [3.20-5.43]) compared to non-key workers, but lower in hospitality and retail workers(OR 0.73 [0.64-0.82] and 0.77 [0.70-0.85] respectively) after adjusting for age and keycovariates.

Working paper

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 Pet al., 2021, 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

BackgroundDespite high levels of vaccination in the adult population, cases of COVID-19 have risenexponentially in England since the start of May 2021 driven by the Delta variant. However,with far fewer hospitalisations and deaths per case during the recent growth in casescompared with 2020, it is intended that all remaining social distancing legislation in Englandwill be removed from 19 July 2021.MethodsWe report interim results from round 13 of the REal-time Assessment of CommunityTransmission-1 (REACT-1) study in which a cross-sectional sample of the population ofEngland was asked to provide a throat and nose swab for RT-PCR and to answer aquestionnaire. Data collection for this report (round 13 interim) was from 24 June to 5 July2021.ResultsIn round 13 interim, we found 237 positives from 47,729 swabs giving a weighted prevalenceof 0.59% (0.51%, 0.68%) which was approximately four-fold higher compared with round 12at 0.15% (0.12%, 0.18%). This resulted from continued exponential growth in prevalencewith an average doubling time of 15 (13, 17) days between round 12 and round 13.However, during the recent period of round 13 interim only, we observed a shorter doublingtime of 6.1 (4.0, 12) days with a corresponding R number of 1.87 (1.40, 2.45). There weresubstantial increases in all age groups under the age of 75 years, and especially at youngerages, with the highest prevalence in 13 to 17 year olds at 1.33% (0.97%, 1.82%) and in 18 to24 years olds at 1.40% (0.89%, 2.18%). Infections have increased in all regions with thelargest increase in London where prevalence increased more than eight-fold from 0.13%(0.08%, 0.20%) in round 12 to 1.08% (0.79%, 1.47%) in round 13 interim. Overall,prevalence was over 3 times higher in the unvaccinated compared with those reporting twodoses of vaccine in both round 12 and round 13 interim, although there was a similarproportional increase in prevalence in vaccinated and unvaccinated individuals between thetwo rounds.DiscussionWe

Working paper

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 Get al., 2021, Acceptability, usability and performance of lateral flow immunoassay tests for SARSCoV-2 antibodies: REACT-2 study of self-testing in non-healthcare key workers, Publisher: Cold Spring Harbor Laboratory

BackgroundSeroprevalence studies in key worker populations are essential to understand the epidemiology of SARS-CoV-2. Various technologies, including laboratory assays and pointof-care self-tests, are available for antibody testing. The interpretation of seroprevalence studies requires comparative data on the performance of antibody tests.MethodsIn June 2020, current and former members of the UK Police forces and Fire service performed a self-test lateral flow immunoassay (LFIA) and provided a saliva sample, nasopharyngeal swab, venous blood samples for Abbott ELISA and had a nurse performed LFIA. We present the prevalence of PCR positivity and antibodies to SARS-CoV-2 in this cohort following the first wave of infection in England; the acceptability and usability of selftest LFIAs (defined as use of the LFIA kit and provision of a valid result, respectively); and determine the sensitivity and specificity of LFIAs compared to laboratory ELISAs.ResultsIn this cohort of non-healthcare key workers, 7.4% (396/5,348; 95% CI, 6.7-8.1) were antibody positive. Seroprevalence was 8.9% (6.9-11.4) in those under 40 years, 11.5% (8.8-15.0) in those of non-white British ethnicity and 7.8% (7.1-8.7) in those currently working.The self-test LFIA had an acceptability of 97.7% and a usability of 90.0%. There was substantial agreement between within-participant LFIA results (kappa 0.80; 0.77-0.83). The LFIAs (self-test and nurse-performed) had a similar performance: compared to ELISA, sensitivity was 82.1% (77.7-86.0) self-test and 76.4% (71.9-80.5) nurse-performed with specificity of 97.8% (97.3-98.2) and 98.5% (98.1-98.8) respectively.ConclusionA greater proportion of the non-healthcare key worker cohort showed evidence of previous infection with SARS-CoV-2 than the general population at 6.0% (5.8-6.1) following the first wave in England. The high acceptability and usability reported by participants and the similar performance of self-test and nurse-performed LFIAs indicate that t

Working paper

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 Pet al., 2021, REACT-1 round 12 report: resurgence of SARS-CoV-2 infections in England associated with increased frequency of the Delta variant

BackgroundEngland entered a third national lockdown from 6 January 2021 due to the COVID-19pandemic. Despite a successful vaccine rollout during the first half of 2021, cases andhospitalisations have started to increase since the end of May as the SARS-CoV-2 Delta(B.1.617.2) variant increases in frequency. The final step of relaxation of COVID-19restrictions in England has been delayed from 21 June to 19 July 2021.MethodsThe REal-time Assessment of Community Transmision-1 (REACT-1) study measures theprevalence of swab-positivity among random samples of the population of England. Round12 of REACT-1 obtained self-administered swab collections from participants from 20 May2021 to 7 June 2021; results are compared with those for round 11, in which swabs werecollected from 15 April to 3 May 2021.ResultsBetween rounds 11 and 12, national prevalence increased from 0.10% (0.08%, 0.13%) to0.15% (0.12%, 0.18%). During round 12, we detected exponential growth with a doublingtime of 11 (7.1, 23) days and an R number of 1.44 (1.20, 1.73). The highest prevalence wasfound in the North West at 0.26% (0.16%, 0.41%) compared to 0.05% (0.02%, 0.12%) in theSouth West. In the North West, the locations of positive samples suggested a cluster inGreater Manchester and the east Lancashire area. Prevalence in those aged 5-49 was 2.5times higher at 0.20% (0.16%, 0.26%) compared with those aged 50 years and above at0.08% (0.06%, 0.11%). At the beginning of February 2021, the link between infection ratesand hospitalisations and deaths started to weaken, although in late April 2021, infectionrates and hospital admissions started to reconverge. When split by age, the weakened linkbetween infection rates and hospitalisations at ages 65 years and above was maintained,while the trends converged below the age of 65 years. The majority of the infections in theyounger group occurred in the unvaccinated population or those without a stated vaccinehistory. We observed the rapid replacement of the Alpha (

Working paper

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, Darzi A, Elliott Pet al., 2021, Resurgence of SARS-CoV-2: detection by community viral surveillance, Science, Vol: 372, Pages: 990-995, ISSN: 0036-8075

Surveillance of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has mainly relied on case reporting, which is biased by health service performance, test availability, and test-seeking behaviors. We report a community-wide national representative surveillance program in England based on self-administered swab results from ~594,000 individuals tested for SARS-CoV-2, regardless of symptoms, between May and the beginning of September 2020. The epidemic declined between May and July 2020 but then increased gradually from mid-August, accelerating into early September 2020 at the start of the second wave. When compared with cases detected through routine surveillance, we report here a longer period of decline and a younger age distribution. Representative community sampling for SARS-CoV-2 can substantially improve situational awareness and feed into the public health response even at low prevalence.

Journal article

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 Pet al., 2021, 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

BackgroundNational epidemic dynamics of SARS-CoV-2 infections are being driven by: the degree of recent indoor mixing (both social and workplace), vaccine coverage, intrinsic properties of the circulating lineages, and prior history of infection (via natural immunity). In England, infections, hospitalisations and deaths fell during the first two steps of the “roadmap” for exiting the third national lockdown. The third step of the roadmap in England takes place on 17 May 2021.MethodsWe report the most recent findings on community infections from the REal-time Assessment of Community Transmission-1 (REACT-1) study in which a swab is obtained from a representative cross-sectional sample of the population in England and tested using PCR. Round 11 of REACT-1 commenced self-administered swab-collection on 15 April 2021 and completed collections on 3 May 2021. We compare the results of REACT-1 round 11 to round 10, in which swabs were collected from 11 to 30 March 2021.ResultsBetween rounds 10 and 11, prevalence of swab-positivity dropped by 50% in England from 0.20% (0.17%, 0.23%) to 0.10% (0.08%, 0.13%), with a corresponding R estimate of 0.90 (0.87, 0.94). Rates of swab-positivity fell in the 55 to 64 year old group from 0.17% (0.12%, 0.25%) in round 10 to 0.06% (0.04%, 0.11%) in round 11. Prevalence in round 11 was higher in the 25 to 34 year old group at 0.21% (0.12%, 0.38%) than in the 55 to 64 year olds and also higher in participants of Asian ethnicity at 0.31% (0.16%, 0.60%) compared with white participants at 0.09% (0.07%, 0.11%). Based on sequence data for positive samples for which a lineage could be identified, we estimate that 92.3% (75.9%, 97.9%, n=24) of infections were from the B.1.1.7 lineage compared to 7.7% (2.1%, 24.1%, n=2) from the B.1.617.2 lineage. Both samples from the B.1.617.2 lineage were detected in London from participants not reporting travel in the previous two weeks. Also, allowing for suitable lag periods, the prior close alig

Working paper

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 Set al., 2021, SARS-CoV-2 lineage dynamics in England from January to March 2021 inferred from representative community samples

Genomic surveillance for SARS-CoV-2 lineages informs our understanding of possible future changes in transmissibility and vaccine efficacy. However, small changes in the frequency of one lineage over another are often difficult to interpret because surveillance samples are obtained from a variety of sources. Here, we describe lineage dynamics and phylogenetic relationships using sequences obtained from a random community sample who provided a throat and nose swab for rt-PCR during the first three months of 2021 as part of the REal-time Assessment of Community Transmission-1 (REACT-1) study. Overall, diversity decreased during the first quarter of 2021, with the B.1.1.7 lineage (first identified in Kent) predominant, driven by a 0.3 unit higher reproduction number over the prior wild type. During January, positive samples were more likely B.1.1.7 in younger and middle-aged adults (aged 18 to 54) than in other age groups. Although individuals infected with the B.1.1.7 lineage were no more likely to report one or more classic COVID-19 symptoms compared to those infected with wild type, they were more likely to be antibody positive 6 weeks after infection. Viral load was higher in B.1.1.7 infection as measured by cycle threshold (Ct) values, but did not account for the increased rate of testing positive for antibodies. The presence of infections with non-imported B.1.351 lineage (first identified in South Africa) during January, but not during February or March, suggests initial establishment in the community followed by fade-out. However, this occurred during a period of stringent social distancing and targeted public health interventions and does not immediately imply similar lineages could not become established in the future. Sequence data from representative community surveys such as REACT-1 can augment routine genomic surveillance.

Working paper

Riley S, Eales O, Haw D, Walters C, Wang H, Ainslie K, Atchison C, Fronterre C, Diggle P, Ashby D, Donnelly C, Cooke G, Barclay W, Ward H, Darzi A, Elliott Pet al., 2021, REACT-1 round 10 report: Level prevalence of SARS-CoV-2 swab-positivity in England during third national lockdown in March 2021

BackgroundIn England, hospitalisations and deaths due to SARS-CoV-2 have been falling consistentlysince January 2021 during the third national lockdown of the COVID-19 pandemic. The firstsignificant relaxation of that lockdown occurred on 8 March when schools reopened.MethodsThe REal-time Assessment of Community Transmission-1 (REACT-1) study augmentsroutine surveillance data for England by measuring swab-positivity for SARS-CoV-2 in thecommunity. The current round, round 10, collected swabs from 11 to 30 March 2021 and iscompared here to round 9, in which swabs were collected from 4 to 23 February 2021.ResultsDuring round 10, we estimated an R number of 1.00 (95% confidence interval 0.81, 1.21).Between rounds 9 and 10 we estimated national prevalence has dropped by ~60% from0.49% (0.44%, 0.55%) in February to 0.20% (0.17%, 0.23%) in March. There weresubstantial falls in weighted regional prevalence: in South East from 0.36% (0.29%, 0.44%)in round 9 to 0.07% (0.04%, 0.12%) in round 10; London from 0.60% (0.48%, 0.76%) to0.16% (0.10%, 0.26%); East of England from 0.47% (0.36%, 0.60%) to 0.15% (0.10%,0.24%); East Midlands from 0.59% (0.45%, 0.77%) to 0.19% (0.13%, 0.28%); and NorthWest from 0.69% (0.54%, 0.88%) to 0.31% (0.21%, 0.45%). Areas of apparent higherprevalence remain in parts of the North West, and Yorkshire and The Humber. The highestprevalence in March was found among school-aged children 5 to 12 years at 0.41% (0.27%,0.62%), compared with the lowest in those aged 65 to 74 and 75 and over at 0.09% (0.05%,0.16%). The close approximation between prevalence of infections and deaths (suitablylagged) is diverging, suggesting that infections may have resulted in fewer hospitalisationsand deaths since the start of widespread vaccination.ConclusionWe report a sharp decline in prevalence of infections between February and March 2021.We did not observe an increase in the prevalence of SARS-CoV-2 following the reopening ofschools in England, although the decline of p

Working paper

Bowman L, Kwok KO, Redd R, Yi Y, Ward H, Wei WI, Atchison C, Wong SY-Set al., 2021, Comparing Public Perceptions and Preventive Behaviors During the Early Phase of the COVID-19 Pandemic in Hong Kong and the United Kingdom: Cross-sectional Survey Study, JOURNAL OF MEDICAL INTERNET RESEARCH, Vol: 23, ISSN: 1438-8871

Journal article

Riley S, Wang H, Eales O, Haw D, Walters C, Ainslie K, Atchison C, Fronterre C, Diggle P, Ashby D, Donnelly C, Cooke G, Barclay W, Ward H, Darzi A, Elliott Pet al., 2021, REACT-1 round 9 final report: Continued but slowing decline of prevalence of SARS-CoV-2 during national lockdown in England in February 2021

BackgroundEngland will start to exit its third national lockdown in response to the COVID-19 pandemicon 8th March 2021, with safe effective vaccines being rolled out rapidly against abackground of emerging transmissible and immunologically novel variants of SARS-CoV-2.A subsequent increase in community prevalence of infection could delay further relaxation oflockdown if vaccine uptake and efficacy are not sufficiently high to prevent increasedpressure on healthcare services.MethodsThe PCR self-swab arm of the REal-time Assessment of Community Transmission Study(REACT-1) estimates community prevalence of SARS-CoV-2 infection in England based onrandom cross-sections of the population ages five and over. Here, we present results fromthe complete round 9 of REACT-1 comprising round 9a in which swabs were collected from4th to 12th February 2021 and round 9b from 13th to 23rd February 2021. We also comparethe results of REACT-1 round 9 to round 8, in which swabs were collected mainly from 6thJanuary to 22nd January 2021.ResultsOut of 165,456 results for round 9 overall, 689 were positive. Overall weighted prevalence ofinfection in the community in England was 0.49% (0.44%, 0.55%), representing a fall of overone third from round 8. However the rate of decline of the epidemic has slowed from 15 (13,17) days, estimated for the period from the end of round 8 to the start of round 9, to 31 daysestimated using data from round 9 alone (lower confidence limit 17 days). When comparinground 9a to 9b there were apparent falls in four regions, no apparent change in one regionand apparent rises in four regions, including London where there was a suggestion ofsub-regional heterogeneity in growth and decline. Smoothed prevalence maps suggest largecontiguous areas of growth and decline that do not align with administrative regions.Prevalence fell by 50% or more across all age groups in round 9 compared to round 8, withprevalence (round 9) ranging from 0.21% in those aged 65 and over to 0

Working paper

Moshe M, Daunt A, Flower B, Simmons B, Brown JC, Frise R, Penn R, Kugathasan R, Petersen C, Stockmann H, Ashby D, Riley S, Atchison C, Taylor GP, Satkunarajah S, Naar L, Klaber R, Badhan A, Rosadas C, Marchesin F, Fernandez N, Sureda-Vives M, Cheeseman H, O'Hara J, Shattock R, Fontana G, Pallett SJC, Rayment M, Jones R, Moore LSP, Ashrafian H, Cherapanov P, Tedder R, McClure M, Ward H, Darzi A, Cooke GS, Barclay WS, On behalf of the REACT Study teamet al., 2021, SARS-CoV-2 lateral flow assays for possible use in national covid-19 seroprevalence surveys (REACT2): diagnostic accuracy study, BMJ: British Medical Journal, Vol: 372, Pages: 1-8, ISSN: 0959-535X

Objective: To evaluate the performance of new lateral flow immunoassays (LFIAs) suitable for use in a national COVID-19 seroprevalence programme (REACT2).Design: Laboratory sensitivity and specificity analyses were performed for seven LFIAs on a minimum of 200 sera from individuals with confirmed SARS-CoV-2 infection, and 500 pre-pandemic sera respectively. Three LFIAs were found to have a laboratory sensitivity superior to the finger-prick sensitivity of the LFIA currently used in REACT2 seroprevalence studies (84%). These LFIAs were then further evaluated through finger-prick testing on participants with confirmed previous SARS-CoV-2 infection. Two LFIAs (Surescreen, Panbio) were evaluated in clinics in June-July, 2020, and a third LFIA (AbC-19) in September, 2020. A Spike protein enzyme-linked immunoassay (S-ELISA) and hybrid double antigen binding assay (DABA) were used as laboratory reference standards.Setting: Laboratory analyses were performed at Imperial College, London and University facilities in London, UK. Research clinics for finger-prick sampling were run in two affiliated NHS trusts.Participants: Sensitivity analysis on sera were performed on 320 stored samples from previous participants in the REACT2 programme with confirmed previous SARS-CoV-2 infection. Specificity analysis was performed using 1000 pre-pandemic sera. 100 new participants with confirmed previous SARS-CoV-2 infection attended study clinics for finger-prick testing.Main outcome measures: The accuracy of LFIAs in detecting IgG antibodies to SARS-CoV-2 in comparison to two in-house ELISAs.Results: The sensitivity of seven new LFIAs using sera varied between 69% and 100% (vs S-ELISA/hybrid DABA). Specificity using sera varied between 99.6% and 100%. Sensitivity on finger-prick testing for Panbio, Surescreen and AbC-19 was 77% (CI 61.4 to 88.2), 86% (CI 72.7 to 94.8) and 69% (CI 53.8 to 81.3) respectively vs S-ELISA/hybrid DABA. Sensitivity for sera from matched clinical samples performe

Journal article

Ward H, Cooke G, Whitaker M, Redd R, Eales O, Brown J, Collet K, Cooper E, Daunt A, Jones K, Moshe M, Willicombe M, Day S, Atchison C, Darzi A, Donnelly C, Riley S, Ashby D, Barclay W, Elliott Pet al., 2021, REACT-2 Round 5: increasing prevalence of SARS-CoV-2 antibodies demonstrate impact of the second wave and of vaccine roll-out in England

BackgroundEngland has experienced high rates of SARS-CoV-2 infection during the COVID-19 pandemic, affecting in particular minority ethnic groups and more deprived communities. A vaccination programme began in England in December 2020, with priority given to administering thefirst dose to the largest number of older individuals, healthcare and care home workers.MethodsA cross-sectional community survey in England undertaken between 26 January and 8 February 2021 as the fifth round of the REal-time Assessment of Community Transmission-2 (REACT-2) programme. Participants completed questionnaires, including demographic details and clinical and COVID-19 vaccination histories, and self-administered a lateral flowimmunoassay (LFIA) test to detect IgG against SARS-CoV-2 spike protein. There were sufficient numbers of participants to analyse antibody positivity after 21 days from vaccination with the PfizerBioNTech but not the AstraZeneca/Oxford vaccine which was introduced slightly later.ResultsThe survey comprised 172,099 people, with valid IgG antibody results from 155,172. The overall prevalence of antibodies (weighted to be representative of the population of England and adjusted for test sensitivity and specificity) in England was 13.9% (95% CI 13.7, 14.1) overall, 37.9% (37.2, 38.7) in vaccinated and 9.8% (9.6, 10.0) in unvaccinated people.The prevalence of antibodies (weighted) in unvaccinated people was highest in London at 16.9% (16.3, 17.5), and higher in people of Black (22.4%, 20.8, 24.1) and Asian (20.0%, 19.0, 21.0) ethnicity compared to white (8.5%, 8.3, 8.7) people. The uptake of vaccination by age was highest in those aged 80 years or older (93.5%). Vaccine confidence was high with 92.0% (91.9, 92.1) of people saying that they had accepted or intended to accept the offer.Vaccine confidence varied by age and ethnicity, with lower confidence in young people and those of Black ethnicity. Particular concerns were identified around pregnancy, fertility and alle

Working paper

Riley S, Walters C, Wang H, Eales O, Haw D, Ainslie K, Atchison C, Fronterre C, Diggle P, Ashby D, Donnelly C, Cooke G, Barclay W, Ward H, Darzi A, Elliott Pet al., 2021, REACT-1 round 9 interim report: downward trend of SARS-CoV-2 in England in February 2021 but still at high prevalence

Background and Methods: England entered its third national lockdown of the COVID-19pandemic on 6th January 2021 with the aim of reducing the daily number of deaths andpressure on healthcare services. The real-time assessment of community transmission study(REACT-1) obtains throat and nose swabs from randomly selected people in England inorder to describe patterns of SARS-CoV-2 prevalence. Here, we report data from round 9aof REACT-1 for swabs collected between 4th and 13th February 2021.Results: Out of 85,473 tested-swabs, 378 were positive. Overall weighted prevalence ofinfection in the community in England was 0.51%, a fall of more than two thirds since our lastreport (round 8) in January 2021 when 1.57% of people tested positive. We estimate ahalving time of 14.6 days and a reproduction number R of 0.72, based on the difference inprevalence between the end of round 8 and the beginning of round 9. Although prevalencefell in all nine regions of England over the same period, there was greater uncertainty in thetrend for North West, North East, and Yorkshire and The Humber. Prevalence fellsubstantially across all age groups with highest prevalence among 18- to 24-year olds at0.89% (0.47%, 1.67%) and those aged 5 to12 years at 0.86% (0.60%, 1.24%). Largehousehold size, living in a deprived neighbourhood, and Asian ethnicity were all associatedwith increased prevalence. Healthcare and care home workers were more likely to testpositive compared to other workers.Conclusions: There is a strong decline in prevalence of SARS-CoV-2 in England among thegeneral population five to six weeks into lockdown, but prevalence remains high: at levelssimilar to those observed in late September 2020. Also, the number of COVID-19 cases inhospitals is higher than at the peak of the first wave in April 2020. The effects of easing ofsocial distancing when we transition out of lockdown need to be closely monitored to avoid aresurgence in infections and renewed pressure on health services.

Working paper

Ward H, Atchison C, Whitaker M, Ainslie KEC, Elliott J, Okell L, Redd R, Ashby D, Donnelly C, Barclay W, Darzi A, Cooke G, Riley S, Elliott Pet al., 2021, SARS-CoV-2 antibody prevalence in England following the first peak of the pandemic., Nature Communications, Vol: 12, Pages: 1-8, ISSN: 2041-1723

England has experienced a large outbreak of SARS-CoV-2, disproportionately affecting people from disadvantaged and ethnic minority communities. It is unclear how much of this excess is due to differences in exposure associated with structural inequalities. Here we report from the REal-time Assessment of Community Transmission-2 (REACT-2) national study of over 100,000 people. After adjusting for test characteristics and re-weighting to the population, overall antibody prevalence is 6.0% (95% CI: 5.8-6.1). An estimated 3.4 million people had developed antibodies to SARS-CoV-2 by mid-July 2020. Prevalence is two- to three-fold higher among health and care workers compared with non-essential workers, and in people of Black or South Asian than white ethnicity, while age- and sex-specific infection fatality ratios are similar across ethnicities. Our results indicate that higher hospitalisation and mortality from COVID-19 in minority ethnic groups may reflect higher rates of infection rather than differential experience of disease or care.

Journal article

Riley S, Eales O, Walters C, Wang H, Ainslie K, Atchison C, Fronterre C, Diggle P, Ashby D, Donnelly C, Cooke G, Barclay W, Darzi A, Elliott P, Ward Het al., 2021, REACT-1 round 8 final report: high average prevalence with regional heterogeneity of trends in SARS-CoV-2 infection in the community in England during January 2021

In early January 2021, England entered its third national lockdown of the COVID-19 pandemic to reduce numbers of deaths and pressure on healthcare services, while rapidly rolling out vaccination to healthcare workers and those most at risk of severe disease and death. REACT-1 is a survey of SARS-CoV-2 prevalence in the community in England, based on repeated cross-sectional samples of the population. Between 6th and 22nd January 2021, out of 167,642 results, 2,282 were positive giving a weighted national prevalence of infection of 1.57% (95% CI, 1.49%, 1.66%). The R number nationally over this period was estimated at 0.98 (0.92, 1.04). Prevalence remained high throughout, but with suggestion of a decline at the end of the study period. The average national trend masked regional heterogeneity, with robustly decreasing prevalence in one region (South West) and increasing prevalence in another (East Midlands). Overall prevalence at regional level was highest in London at 2.83% (2.53%, 3.16%). Although prevalence nationally was highest in the low-risk 18 to 24 year old group at 2.44% (1.96%, 3.03%), it was also high in those over 65 years who are most at risk, at 0.93% (0.82%, 1.05%). Large household size, living in a deprived neighbourhood, and Black and Asian ethnicity were all associated with higher levels of infections compared to smaller households, less deprived neighbourhoods and other ethnicities. Healthcare and care home workers, and other key workers, were more likely to test positive compared to other workers. If sustained lower prevalence is not achieved rapidly in England, pressure on healthcare services and numbers of COVID-19 deaths will remain unacceptably high.

Working paper

Riley S, Wang H, Eales O, Walters C, Ainslie K, Atchison C, Fronterre C, Diggle P, Ashby D, Donnelly C, Cooke G, Barclay W, Ward H, Darzi A, Elliott Pet al., 2021, REACT-1 round 8 interim report: SARS-CoV-2 prevalence during the initial stages of the third national lockdown in England, Publisher: Imperial College London

BackgroundHigh prevalence of SARS-CoV-2 virus in many northern hemisphere populations is causingextreme pressure on healthcare services and leading to high numbers of fatalities. Eventhough safe and effective vaccines are being deployed in many populations, the majority ofthose most at-risk of severe COVID-19 will not be protected until late spring, even incountries already at a more advanced stage of vaccine deployment.MethodsThe REal-time Assessment of Community Transmission study-1 (REACT-1) obtains throatand nose swabs from between 120,000 and 180,000 people in the community in England atapproximately monthly intervals. Round 8a of REACT-1 mainly covers a period from 6thJanuary 2021 to 15th January 2021. Swabs are tested for SARS-CoV-2 virus and patterns ofswab-positivity are described over time, space and with respect to individual characteristics.We compare swab-positivity prevalence from REACT-1 with mobility data based on the GPSlocations of individuals using the Facebook mobile phone app. We also compare resultsfrom round 8a with those from round 7 in which swabs were collected from 13th Novemberto 24th November (round 7a) and 25th November to 3rd December 2020 (round 7b).ResultsIn round 8a, we found 1,962 positives from 142,909 swabs giving a weighted prevalence of1.58% (95% CI, 1.49%, 1.68%). Using a constant growth model, we found no strongevidence for either growth or decay averaged across the period; rather, based on data froma limited number of days, prevalence may have started to rise at the end of round 8a.Facebook mobility data showed a marked decrease in activity at the end of December 2020,followed by a rise at the start of the working year in January 2021. Between round 7b andround 8a, prevalence increased in all adult age groups, more than doubling to 0.94%(0.83%, 1.07%) in those aged 65 and over. Large household size, living in a deprivedneighbourhood, and Black and Asian ethnicity were all associated with increasedprevalence. Both healthcare

Working paper

Atchison C, Bowman LR, Vrinten C, Redd R, Pristerà P, Eaton J, Ward Het al., 2021, Early perceptions and behavioural responses during the COVID-19 pandemic: a cross-sectional survey of UK adults., BMJ Open, Vol: 11, Pages: 1-12, ISSN: 2044-6055

OBJECTIVE: To examine risk perceptions and behavioural responses of the UK adult population during the early phase of the COVID-19 epidemic in the UK. DESIGN: A cross-sectional survey. SETTING: Conducted with a nationally representative sample of UK adults within 48 hours of the UK Government advising the public to stop non-essential contact with others and all unnecessary travel. PARTICIPANTS: 2108 adults living in the UK aged 18 years and over. Response rate was 84.3% (2108/2500). Data collected between 17 March and 18 March 2020. MAIN OUTCOME MEASURES: Descriptive statistics for all survey questions, including number of respondents and weighted percentages. Robust Poisson regression used to identify sociodemographic variation in: (1) adoption of social distancing measures, (2) ability to work from home, and (3) ability and (4) willingness to self-isolate. RESULTS: Overall, 1992 (94.2%) respondents reported at least one preventive measure: 85.8% washed their hands with soap more frequently; 56.5% avoided crowded areas and 54.5% avoided social events. Adoption of social distancing measures was higher in those aged over 70 years compared with younger adults aged 18-34 years (adjusted relative risk/aRR: 1.2; 95% CI: 1.1 to 1.5). Those with lowest household income were three times less likely to be able to work from home (aRR: 0.33; 95% CI: 0.24 to 0.45) and less likely to be able to self-isolate (aRR: 0.92; 95% CI: 0.88 to 0.96). Ability to self-isolate was also lower in black and minority ethnic groups (aRR: 0.89; 95% CI: 0.79 to 1.0). Willingness to self-isolate was high across all respondents. CONCLUSIONS: Ability to adopt and comply with certain non-pharmaceutical interventions (NPIs) is lower in the most economically disadvantaged in society. Governments must implement appropriate social and economic policies to mitigate this. By incorporating these differences in NPIs among socioeconomic subpopulations into mathematical models of COV

Journal article

Riley S, Walters C, Wang H, Eales O, Ainslie K, Atchison C, Fronterre C, Diggle PJ, Ashby D, Donnelly C, Cooke G, Barclay W, Ward H, Darzi A, Elliott Pet al., 2020, REACT-1 round 7 updated report: regional heterogeneity in changes in prevalence of SARS-CoV-2 infection during the second national COVID-19 lockdown in England, REACT-1 round 7 updated report: regional heterogeneity in changes in prevalence of SARS-CoV-2 infection during the second national COVID-19 lockdown in England, London, Publisher: Imperial College London

BackgroundEngland exited a four-week second national lockdown on 2nd December 2020 initiated in response to the COVID-19 pandemic. Prior results showed that prevalence dropped during the first half of lockdown, with greater reductions in higher-prevalence northern regions.MethodsREACT-1 is a series of community surveys of SARS-CoV-2 RT-PCR swab-positivity in England, designed to monitor the spread of the epidemic and thus increase situational awareness. Round 7 of REACT-1 commenced swab-collection on 13th November 2020. A prior interim report included data from 13th to 24th November 2020 for 105,122 participants. Here, we report data for the entire round with swab results obtained up to 3rd December 2020.ResultsBetween 13th November and 3rd December (round 7) there were 1,299 positive swabs out of 168,181 giving a weighted prevalence of 0.94% (95% CI 0.87%, 1.01%) or 94 per 10,000 people infected in the community in England. This compares with a prevalence of 1.30% (1.21%, 1.39%) from 16th October to 2nd November 2020 (round 6), a decline of 28%. Prevalence during the latter half of round 7 was 0.91% (95% CI, 0.81%, 1.03%) compared with 0.96% (0.87%, 1.05%) in the first half. The national R number in round 7 was estimated at 0.96 (0.88, 1.03) with a decline in prevalence observed during the first half of this period no longer apparent during the second half at the end of lockdown. During round 7 there was a marked fall in prevalence in West Midlands, a levelling off in some regions and a rise in London. R numbers at regional level ranged from 0.60 (0.41, 0.80) in West Midlands up to 1.27 (1.04, 1.54) in London, where prevalence was highest in the east and south-east of the city. Nationally, between 13th November and 3rd December, the highest prevalence was in school-aged children especially at ages 13-17 years at 2.04% (1.69%, 2.46%), or approximately 1 in 50.ConclusionBetween the previous round and round 7 (during lockdown), there was a fall in prevalence of SARS-C

Report

Castro-Sanchez E, Alexander CM, Atchison C, Patel D, Leung W, Calamita ME, Garcia DM, Cimpeanu C, Mumbwatasai JM, Ramid D, Doherty K, Grewal HS, Otter JA, Wells EMet al., 2020, Evaluation of a personal protective equipment (PPE) support programme ('PPE Helpers') for staff during the COVID-19 pandemic in London, Journal of Hospital Infection, Vol: 109, Pages: 68-7, ISSN: 0195-6701

BackgroundThe COVID-19 pandemic has presented one of the biggest challenges to healthcare providers worldwide. The appropriate use of Personal Protective Equipment (PPE) has been essential to ensuring staff and patient safety. To counteract sub-optimal PPE practice, a PPE helper programme was developed at a large London hospital group. Based on a behaviour change model of Capability, Opportunity and Motivation (COM-B), the programme provided PPE support, advice and education to ward staff.AimEvaluation of the PPE Helper Programme.MethodsClinical and non-clinical ward staff completed a questionnaire informed by the Theoretical Domains Framework and COM-B. The questionnaire was available in paper and electronic versions. Quantitative responses were analysed using descriptive and non-parametric statistics, free-text responses were analysed thematically.FindingsOver a six-week period, PPE helpers made 268 ward visits. Overall, 261 questionnaires were available for analysis. Across the Trust, 68% of respondents reported having had contact with a PPE helper. Staff who had encountered a PPE helper responded significantly more positively to a range of statements about using PPE than those who had not. Black and Minority Ethnic (BAME) staff were significantly more anxious in relation to the adequacy of PPE. Non-clinical and redeployed staff (e.g. domestic staff) were most positive about the impact of PPE helpers. Free-text comments showed that staff found the programme supportive and would have liked it earlier in the pandemic.ConclusionA PPE Helper programme is a feasible and beneficial intervention for providing support, advice and education to ward staff during infectious disease outbreaks.

Journal article

Riley S, Eales O, Walters C, Wang H, Ainslie K, Atchison C, Fronterre C, Diggle P, Ashby D, Donnelly C, Cooke G, Barclay W, Ward H, Darzi A, Elliott Pet al., 2020, REACT-1 round 7 interim report: fall in prevalence of swab-positivity in England during national lockdown, Publisher: Cold Spring Harbor Laboratory

Background The second wave of the 2020 COVID-19 pandemic in England has been characterized by high growth and prevalence in the North with lower prevalence in the South. High prevalence was first observed at younger adult ages before spreading out to school-aged children and older adults. Local tiered interventions were in place up to 5th November 2020 at which time a second national lockdown was implemented.Methods REACT-1 is a repeated cross-sectional survey of SARS-CoV-2 swab-positivity in random samples of the population of England. The current period of data collection (round 7) commenced on 13th November 2020 and we report interim results here for swabs collected up to and including 24th November 2020. Because there were two distinct periods of growth during the previous round 6, here we compare results from round 7 (mainly) with the second half of round 6, which obtained swabs between 26th October and 2nd November 2020. We report prevalence both unweighted and reweighted to be representative of the population of England. We describe trends in unweighted prevalence with daily growth rates, doubling times, reproduction numbers (R) and splines. We estimated odds ratios for swab-positivity using mutually-adjusted multivariable logistic regression models.Results We found 821 positives from 105,123 swabs giving an unweighted prevalence of 0.78% (95% CI, 0.73%, 0.84%) and a weighted prevalence of 0.96% (0.87%, 1.05%). The weighted prevalence estimate was ∼30% lower than that of 1.32% (1.20%, 1.45%) obtained in the second half of round 6. This decrease corresponds to a halving time of 37 (30, 47) days and an R number of 0.88 (0.86, 0.91). Using only data from the most recent period, we estimate an R number of 0.71 (0.54, 0.90). A spline fit to prevalence showed a rise shortly after the previous period of data collection followed by a fall coinciding with the start of lockdown. The national trends were driven mainly by reductions in higher-prevalence northern regi

Working paper

Riley S, Ainslie K, Eales O, Walters CE, Wang H, Atchinson C, Fronterre C, Diggle PJ, Ashby D, Donnelly C, Cooke G, Barclay W, Ward H, Darzi A, Elliott Pet al., 2020, 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

BackgroundEngland is now in the midst of its second wave of the COVID-19 pandemic. Multiple regions of the country are at high infection prevalence and all areas experienced rapid recent growth of the epidemic during October 2020.MethodsREACT-1 is a series of community surveys of SARS-CoV-2 RT-PCR swab-positivity in England designed to monitor the spread of the epidemic and thus increase situational awareness. Round 6 of REACT-1 commenced swab-collection on 16th October. A prior interim report included data from 16th to 25th October for 85,971 participants. Here, we report data for the entire round on 160,175 participants with swab results obtained up to 2nd November 2020.ResultsOverall weighted prevalence of infection in the community in England was 1.3% or 130 people per 10,000 infected, up from 60 people per 10,000 in the round 5 report (18th September to 5th October 2020), doubling every 24 days on average since the prior round. The corresponding R number was estimated to be 1.2. Prevalence of infection was highest in North West (2.4%, up from 1.2% ), followed by Yorkshire and The Humber (2.3% up from 0.84%), West Midlands (1.6% up from 0.60%), North East (1.5% up from 1.1%), East Midlands (1.3% up from 0.56%), London (0.97%, up from 0.54%), South West (0.80% up from 0.33%), South East (0.69% up from 0.29%), and East of England (0.69% up from 0.30%). Rapid growth in the South observed in the first half of round 6 was no longer apparent in the second half of round 6. We also observed a decline in prevalence in Yorkshire and The Humber during this period. Comparing the first and second halves of round 6, there was a suggestion of decline in weighted prevalence in participants aged 5 to 12 years and in those aged 25 to 44 years. While prevalence remained high, in the second half of round 6 there was suggestion of a slight fall then rise that was seen nationally and also separately in both the North and the South.ConclusionThe impact of the second national lockdown

Working paper

Riley S, Ainslie KEC, Eales O, Walters CE, Wang H, Atchinson CJ, Fronterre C, Diggle PJ, Ashby D, Donnelly CA, Cooke G, Barclay W, Ward H, Darzi A, Elliott Pet al., 2020, High prevalence of SARS-CoV-2 swab positivity and increasing R number in England during October 2020: REACT-1 round 6 interim report, Publisher: medRxiv

Background REACT-1 measures prevalence of SARS-CoV-2 infection in representative samples of the population in England using PCR testing from self-administered nose and throat swabs. Here we report interim results for round 6 of observations for swabs collected from the 16th to 25th October 2020 inclusive. Methods REACT-1 round 6 aims to collect data and swab results from 160,000 people aged 5 and above. Here we report results from the first 86,000 individuals. We estimate prevalence of PCR-confirmed SARS-CoV-2 infection, reproduction numbers (R) and temporal trends using exponential growth or decay models. Prevalence estimates are presented both unweighted and weighted to be representative of the population of England, accounting for response rate, region, deprivation and ethnicity. We compare these interim results with data from round 5, based on swabs collected from 18th September to 5th October 2020 inclusive. Results Overall prevalence of infection in the community in England was 1.28% or 128 people per 10,000, up from 60 per 10,000 in the previous round. Infections were doubling every 9.0 (6.1, 18) days with a national reproduction number (R) estimated at 1.56 (1.27, 1.88) compared to 1.16 (1.05, 1.27) in the previous round. Prevalence of infection was highest in Yorkshire and The Humber at 2.72% (2.12%, 3.50%), up from 0.84% (0.60%, 1.17%), and the North West at 2.27% (1.90%, 2.72%), up from 1.21% (1.01%, 1.46%), and lowest in South East at 0.55% (0.45%, 0.68%), up from 0.29% (0.23%, 0.37%). Clustering of cases was more prevalent in Lancashire, Manchester, Liverpool and West Yorkshire, West Midlands and East Midlands. Interim estimates of R were above 2 in the South East, East of England, London and South West, but with wide confidence intervals. Nationally, prevalence increased across all age groups with the greatest increase in those aged 55-64 at 1.20% (0.99%, 1.46%), up 3-fold from 0.37% (0.30%, 0.46%). In those aged over 65, prevalence was 0.81% (0.58%, 0

Working paper

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, Darzi A, Elliott Pet al., 2020, High and increasing prevalence of SARS-CoV-2 swab positivity in England during end September beginning October 2020: REACT-1 round 5 updated report, Publisher: Cold Spring Harbor Laboratory

<jats:title>Abstract</jats:title><jats:sec><jats:title>Background</jats:title><jats:p>REACT-1 is quantifying prevalence of SARS-CoV-2 infection among random samples of the population in England based on PCR testing of self-administered nose and throat swabs. Here we report results from the fifth round of observations for swabs collected from the 18th September to 5th October 2020. This report updates and should be read alongside our round 5 interim report.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>Representative samples of the population aged 5 years and over in England with sample size ranging from 120,000 to 175,000 people at each round. Prevalence of PCR-confirmed SARS-CoV-2 infection, estimation of reproduction number (R) and time trends between and within rounds using exponential growth or decay models.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>175,000 volunteers tested across England between 18th September and 5th October. Findings show a national prevalence of 0.60% (95% confidence interval 0.55%, 0.71%) and doubling of the virus every 29 (17, 84) days in England corresponding to an estimated national R of 1.16 (1.05, 1.27). These results correspond to 1 in 170 people currently swab-positive for the virus and approximately 45,000 new infections each day. At regional level, the highest prevalence is in the North West, Yorkshire and The Humber and the North East with strongest regional growth in North West, Yorkshire and The Humber and West Midlands.</jats:p></jats:sec><jats:sec><jats:title>Conclusion</jats:title><jats:p>Rapid growth has led to high prevalence of SARS-CoV-2 virus in England, with highest rates in the North of England. Prevalence has increased in all age groups, including those at highest risk. Improved compliance with existing policy and, as necessar

Working paper

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, Darzi A, Elliott Pet al., 2020, High prevalence of SARS-CoV-2 swab positivity in England during September 2020: interim report of round 5 of REACT-1 study, Publisher: Cold Spring Harbor Laboratory Press

Background REACT-1 is a community survey of PCR confirmed swab-positivity for SARS-CoV-2 among random samples of the population in England. This interim report includes data from the fifth round of data collection currently underway for swabs sampled from the 18th to 26th September 2020.Methods Repeated cross-sectional surveys of random samples of the population aged 5 years and over in England with sample size ranging from 120,000 to 160,000 people in each round of data collection. Collection of self-administered nose and throat swab for PCR and questionnaire data. Prevalence of swab-positivity by round and by demographic variables including age, sex, region, ethnicity. Estimation of reproduction number (R) between and within rounds, and time trends using exponential growth or decay model. Assessment of geographical clustering based on boundary-free spatial model.Results Over the 9 days for which data are available, we find 363 positives from 84,610 samples giving a weighted prevalence to date of 0.55% (0.47%, 0.64%) in round 5. This implies that 411,000 (351,000, 478,000) people in England are virus-positive under the assumption that the swab assay is 75% sensitive. Using data from the most recent two rounds, we estimate a doubling time of 10.6 (9.4, 12.0) days covering the period 20th August to 26th September, corresponding to a reproduction number R of 1.47 (1.40, 1.53). Using data only from round 5 we estimate a reproduction number of 1.06 (0.74, 1.46) with probability of 63% that R is greater than 1. Between rounds 4 and 5 there was a marked increase in unweighted prevalence at all ages. In the most recent data, prevalence was highest in the 18 to 24 yrs age group at 0.96% (0.68%, 1.36%). At 65+ yrs prevalence increased 7-fold between rounds 4 and 5 from 0.04% (0.03%, 0.07%) to 0.29% (0.23%, 0.37%). Prevalence increased in all regions between rounds 4 and 5, giving the highest unweighted prevalence in round 5 in the North West at 0.86% (0.69%, 1.06%). In Lond

Working paper

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, Darzi A, Elliott Pet al., 2020, Resurgence of SARS-CoV-2 in England: detection by community antigen surveillance, Publisher: Cold Spring Harbor Laboratory

<jats:title>Summary</jats:title><jats:sec><jats:title>Background</jats:title><jats:p>Based on cases and deaths, transmission of SARS-CoV-2 in England peaked in late March and early April 2020 and then declined until the end of June. Since the start of July, cases have increased, while deaths have continued to decrease.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>We report results from 594,000 swabs tested for SARS-CoV-2 virus obtained from a representative sample of people in England over four rounds collected regardless of symptoms, starting in May 2020 and finishing at the beginning of September 2020. Swabs for the most recent two rounds were taken between 24th July and 11th August and for round 4 between 22nd August and 7th September. We estimate weighted overall prevalence, doubling times between and within rounds and associated reproduction numbers. We obtained unweighted prevalence estimates by sub-groups: age, sex, region, ethnicity, key worker status, household size, for which we also estimated odds of infection. We identified clusters of swab-positive participants who were closer, on average, to other swab-positive participants than would be expected.</jats:p></jats:sec><jats:sec><jats:title>Findings</jats:title><jats:p>Over all four rounds of the study, we found that 72% (67%, 76%) of swab-positive individuals were asymptomatic at the time of swab and in the week prior. The epidemic declined between rounds 1 and 2, and rounds 2 and 3. However, the epidemic was increasing between rounds 3 and 4, with a doubling time of 17 (13, 23) days corresponding to an R value of 1.3 (1.2, 1.4). When analysing round 3 alone, we found that the epidemic had started to grow again with 93% probability. Using only the most recent round 4 data, we estimated a doubling time of 7.7 (5.5, 12.7) days, corresponding to an R value of 1.7 (1.4, 2.0). Cy

Working paper

This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.

Request URL: http://wlsprd.imperial.ac.uk:80/respub/WEB-INF/jsp/search-html.jsp Request URI: /respub/WEB-INF/jsp/search-html.jsp Query String: respub-action=search.html&id=00710765&limit=30&person=true