Résumé
Background: From 12th March 2020, individuals in England were advised to quarantine in their home if a household member tested positive for SARS-CoV-2. A mandatory isolation period of 10 days was introduced on 28th September 2020 and applied to all individuals with COVID-19. We assessed the frequency, timing, and characteristics of recovered COVID-19 cases requiring subsequent quarantine episodes due to household re-exposure. Methods In this case cohort study, all laboratory-confirmed COVID-19 cases notified in England (29th June to 28th December 2020) were analysed to identify consecutive household case(s). Multivariable logistic regression was used to determine associations between case characteristics and need to quarantine following recent infection (within 28 days of diagnosis). Results Among 1,651,550 cases resident in private dwellings and Houses of Multiple Occupancy (HMOs), 56,179 (3.4%) were succeeded by further household cases diagnosed within 11–28 days of their diagnosis. Of 1,641,412 cases arising in private homes, the likelihood of further household cases was highest for Bangladeshi (aOR = 2.20, 95% CI = 2.10–2.31) and Pakistani (aOR = 2.15, 95% CI = 2.08–2.22) individuals compared to White British, as well as among young people (17-24y vs. 25-64y; aOR = 1.19, 95% CI = 1.16–1.22), men (vs. women; aOR = 1.06, 95% CI = 1.04–1.08), London residents (vs. Yorkshire and Humber; aOR = 1.57, 95% CI = 1.52–1.63) and areas of high deprivation (IMD 1 vs. 10; aOR = 1.13, 95% CI = 1.09–1.19). Conclusions Policies requiring quarantine on re-exposure of recently recovered cases differentially impact some of the most disadvantaged populations. Quarantine exemption for individuals recently (
Sujets)
COVID-19Résumé
Background The SARS-CoV-2 Omicron variant (B.1.1.529) has rapidly replaced the Delta variant (B.1.617.2) to become dominant in England. This epidemiological study assessed differences in transmissibility between the Omicron and Delta using two methods and data sources. Methods Omicron and Delta cases were identified through genomic sequencing, genotyping and S-gene target failure in England from 5-11 December 2021. Secondary attack rates for Omicron and Delta using named contacts and household clustering were calculated using national surveillance and contact tracing data. Logistic regression was used to control for factors associated with transmission. Findings Analysis of contact tracing data identified elevated secondary attack rates for Omicron vs Delta in household (15.0% vs 10.8%) and non-household (8.2% vs 3.7%) settings. The proportion of index cases resulting in residential clustering was twice as high for Omicron (16.1%) compared to Delta (7.3%). Transmission was significantly less likely from cases, or in named contacts, in receipt of three compared to two vaccine doses in household settings, but less pronounced for Omicron (aRR 0.78 and 0.88) compared to Delta (aRR 0.62 and 0.68). In non-household settings, a similar reduction was observed for Delta cases and contacts (aRR 0.84 and 0.51) but only for Omicron contacts (aRR 0.76, 95% CI: 0.58-0.93) and not cases in receipt of three vs two doses (aRR 0.95, 0.77-1.16). Interpretation Our study identified increased risk of onward transmission of Omicron, consistent with its successful global displacement of Delta. We identified a reduced effectiveness of vaccination in lowering risk of transmission, a likely contributor for the rapid propagation of Omicron.
Résumé
Background Household transmission has been demonstrated to be an important factor in the population-level growth of COVID-19. UK Health Security Agency (UKHSA) maintains data on positive tests for COVID-19 and the residential addresses of cases. We sought to use this information to characterise clusters of COVID-19 in multi-generational households in England. Methods Using cross-sectional design, cases of COVID-19 were assigned to clusters if they occurred in the same residential property in a 14-day rolling window. Patient demographic data were supplemented with reference to the ONS index of multiple deprivation and population density. Multi-generational households were defined as a cluster with at least three people, with one case in a person who was 0-16 years old and one case in a person who was [≥] 60 years old, with at least 16 years between two members of each age group. Results A total of 3,647,063 COVID-19 cases were reported between 01 April 2020 and 20 May 2021. Of these, 1,980,527 (54.3 %) occurred in residential clusters. Multi-generational households formed 1.5 % of clusters, with these more likely to occur in areas of higher population density and higher relative deprivation. Multi-generational clusters were more common among households of non-White ethnicity and formed larger clusters than non-multi-generational clusters (median cluster size 6, IQR 4-11 vs 3, IQR 3-4, respectively). Conclusion Multi-generational clusters were not highly prevalent in England during the study period, however were more common in certain populations.
Sujets)
COVID-19Résumé
Background: Universities in England returned to in–person teaching in September 2020, requiring a large migration of students across the country. To understand the impact this had on COVID–19 transmission, we identified and described student cases during the 2020 autumn term. Methods: Student COVID–19 cases were identified from two sources: contact tracing records identifying attendance at university prior to onset and residence in student accommodation identified from matching cases’ residential addresses against national property databases. Residential outbreaks were defined as ≥2 cases with specimen dates within 14 days residing in the same property. A matched analysis of COVID–19 rates and trends in towns/cities with and without a university campus was undertaken. Findings: We identified 53,430 student cases between 1 September and 31 December 2020, constituting 2·7% of all cases (n=1,999,180) in this time period; 39,032 reported attendance at a university during contact tracing; 19,901 resided in student accommodation premises. Cases increased rapidly following the start of term driven initially by cases in student accommodation. Over two thirds (72·2% n=14,375) of cases in student accommodation were part of a residential outbreak.Towns/cities with universities saw a threefold increase in rates amongst 18–23 year olds compared to non–university towns. Interpretation: This study suggests that the return to university teaching and associated movement of students in England was linked to large increases in SARS–CoV–2 transmission amongst this population and potentially contributing to subsequent large increases in the wider population surrounding a campus. Funding Information: No funding was received for this work. Declaration of Interests: None of the authors declare any conflicts of interest.Ethics Approval Statement: UKHSA has legal permission, provided by Regulation 3 of The Health Service (Control of Patient Information) Regulations 2002, to process patient confidential information for national surveillance of communicable diseases and as such, individual patient consent is not required.