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Sam Colville

Bio: Sam Colville is an academic researcher. The author has contributed to research in topics: Population & Rate ratio. The author has an hindex of 3, co-authored 4 publications receiving 18 citations.

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Journal ArticleDOI
TL;DR: In this paper, the authors investigated the rate ratio of severe COVID-19 associated with eligibility for the shielding program in Scotland across the first and second waves of the epidemic and the relation of severe CoVid-19 to transmission-related factors in those in shielding and the general population.
Abstract: Clinically vulnerable individuals have been advised to shield themselves during the COVID-19 epidemic. The objectives of this study were to investigate (1) the rate ratio of severe COVID-19 associated with eligibility for the shielding programme in Scotland across the first and second waves of the epidemic and (2) the relation of severe COVID-19 to transmission-related factors in those in shielding and the general population. In a matched case-control design, all 178,578 diagnosed cases of COVID-19 in Scotland from 1 March 2020 to 18 February 2021 were matched for age, sex and primary care practice to 1,744,283 controls from the general population. This dataset (REACT-SCOT) was linked to the list of 212,702 individuals identified as eligible for shielding. Severe COVID-19 was defined as cases that entered critical care or were fatal. Rate ratios were estimated by conditional logistic regression. With those without risk conditions as reference category, the univariate rate ratio for severe COVID-19 was 3.21 (95% CI 3.01 to 3.41) in those with moderate risk conditions and 6.3 (95% CI 5.8 to 6.8) in those eligible for shielding. The highest rate was in solid organ transplant recipients: rate ratio 13.4 (95% CI 9.6 to 18.8). Risk of severe COVID-19 increased with the number of adults but decreased with the number of school-age children in the household. Severe COVID-19 was strongly associated with recent exposure to hospital (defined as 5 to 14 days before presentation date): rate ratio 12.3 (95% CI 11.5 to 13.2) overall. The population attributable risk fraction for recent exposure to hospital peaked at 50% in May 2020 and again at 65% in December 2020. The effectiveness of shielding vulnerable individuals was limited by the inability to control transmission in hospital and from other adults in the household. Mitigating the impact of the epidemic requires control of nosocomial transmission.

22 citations

Journal ArticleDOI
02 Sep 2021-BMJ
TL;DR: The risk of hospital admission with covid-19 and severe C19 among teachers and their household members, overall and compared with healthcare workers and adults of working age in the general population, was determined in this paper.
Abstract: Objective To determine the risk of hospital admission with covid-19 and severe covid-19 among teachers and their household members, overall and compared with healthcare workers and adults of working age in the general population. Design Population based nested case-control study. Setting Scotland, March 2020 to July 2021, during defined periods of school closures and full openings in response to covid-19. Participants All cases of covid-19 in adults aged 21 to 65 (n=132 420) and a random sample of controls matched on age, sex, and general practice (n=1 306 566). Adults were identified as actively teaching in a Scottish school by the General Teaching Council for Scotland, and their household members were identified through the unique property reference number. The comparator groups were adults identified as healthcare workers in Scotland, their household members, and the remaining general population of working age. Main outcome measures The primary outcome was hospital admission with covid-19, defined as having a positive test result for SARS-CoV-2 during hospital admission, being admitted to hospital within 28 days of a positive test result, or receiving a diagnosis of covid-19 on discharge from hospital. Severe covid-19 was defined as being admitted to intensive care or dying within 28 days of a positive test result or assigned covid-19 as a cause of death. Results Most teachers were young (mean age 42), were women (80%), and had no comorbidities (84%). The risk (cumulative incidence) of hospital admission with covid-19 was Conclusion Compared with adults of working age who are otherwise similar, teachers and their household members were not found to be at increased risk of hospital admission with covid-19 and were found to be at lower risk of severe covid-19. These findings should reassure those who are engaged in face-to-face teaching.

17 citations

Posted ContentDOI
08 Feb 2021-medRxiv
TL;DR: In this paper, the authors conducted a study to determine the risk of hospitalisation with COVID-19 among teachers and their household members, overall and compared to healthcare workers and the general working-age population.
Abstract: Objective To determine the risk of hospitalisation with COVID-19 and severe COVID-19 among teachers and their household members, overall and compared to healthcare workers and the general working-age population. Design Population-based nested case-control study. Settings Scotland, March 2020 to January 2021. Before and after schools re-opened in early August 2020. Participants All cases of COVID-19 in Scotland in adults ages 21 to 65 (n = 83,817) and a random sample of controls matched on age, sex and general practice (n = 841,708). Exposure Individuals identified as actively teaching in a Scottish school by the General Teaching Council for Scotland, and household members of such individuals identified via the Unique Property Reference Number. Comparator Individuals identified as healthcare workers in Scotland, their household members, and the remaining “general population” of working-age adults. Main outcomes The primary outcome was hospitalisation with COVID-19 defined in anyone testing positive with COVID-19 in hospital, admitted to hospital within 28 days of a positive test, and/or diagnosed with COVID-19 on discharge from hospital. Severe COVID-19 was defined as individuals admitted to intensive care or dying within 28 days of a positive test or assigned COVID-19 as a cause of death. Results Most teachers were young (mean age 42), female (80%) and had no underlying conditions (84%). The cumulative incidence (risk) of hospitalisation with COVID-19 was below 1% for all of the working age adults. In the period after school re-opening, compared to the general population, in conditional logistic regression models adjusting for age, sex, general practice, deprivation, underlying conditions and number of adults in the household, the relative risk in teachers (among 18,479 cases and controls) for hospitalisation was rate ratio (RR) 0.97 (95%CI 0.72-1.29) and for severe COVID-19 was RR 0.27 (95%CI 0.09-0.77). Equivalent rate ratios for household members of teachers were 0.97 (95%CI 0.74-1.27) and 0.67 (95%CI 0.36-1.24), and for healthcare workers were 1.82 (95%CI 1.55-2.14) and 1.76 (95%CI 1.22-2.56), respectively. Conclusion Compared to working-age adults who are otherwise similar, teachers and their household members are not at increased risk of hospitalisation with COVID-19 and are at lower risk of severe COVID-19. These findings are broadly reassuring for adults engaged in face to face teaching.

4 citations

Posted ContentDOI
03 Mar 2021-medRxiv
TL;DR: In this article, the authors investigated the risk of severe COVID-19 in those eligible for shielding, and the relation of severe CoV-19 to transmission-related factors in those in shielding and the general population.
Abstract: Objectives To investigate:(1) the risk of severe COVID-19 in those eligible for shielding, and (2) the relation of severe COVID-19 to transmission-related factors in those in shielding and the general population. Design Matched case-control study (REACT-SCOT). Setting Population of Scotland from 1 March 2020 to 28 January 2021. Participants All 160307 diagnosed cases of COVID-19 and 1564782 controls matched for age, sex and primary care practice, linked with all 204913 individuals identified as eligible for shielding by Public Health Scotland. Main outcome measure Severe COVID-19, defined as cases that entered critical care or were fatal. Results With those without risk conditions as reference category, the univariate rate ratio for severe COVID-19 was 5.3 (95% CI 5.0 to 5.7, p=4 × 10−527) in those with moderate risk conditions and 7.6 (95% CI 7.1 to 8.3, p=1 × 10−527) in those eligible for shielding. The highest rate was in solid organ transplant recipients: rate ratio 13.6 (95% CI 9.6 to 19.2, p=8 × 10−50). In both the shielded and the general population, the risk of severe COVID-19 increased with the number of adults but decreased with the number of school-age children in the household. Severe COVID-19 was strongly associated with recent exposure to hospital (defined as 5 to 14 days before presentation date): rate ratio 12.6 (95% CI 11.7 to 13.6, p=2 × 10−989) overall. In a case-crossover analysis with less recent exposure only (15 to 24 days before first testing positive) as reference category, the rate ratio associated with recent exposure only was 6.3 (95% CI 3.6 to 11.1, p=2 × 10−10). Among those eligible for shielding, the population attributable risk fraction (PARF) of severe cases for recent exposure to hospital was 36%. In the general population the PARF for recent exposure to hospital peaked at 46% in May 2020 and again at 64% in December 2020. Conclusions The effectiveness of shielding vulnerable individuals was limited by the inability to control transmission in hospital and from other adults in the household. For solid organ transplant recipients, in whom the efficacy of vaccines is uncertain, these results support a policy of offering vaccination to household contacts. Mitigating the impact of the epidemic requires control of nosocomial transmission. Summary What is already known on this topic? Individuals designated as “clinically extremely vulnerable” – about 3% of the population – have been advised to shield themselves during the COVID-19 epidemic The effectiveness of this shielding programme has not been evaluated. What this study adds Hospital-acquired infection has made a substantial contribution to the burden of COVID-19 in the population, accounting for more than half of severe cases in early December 2020. For vulnerable individuals to be shielded, the risk of hospital-acquired infection must be reduced and support must be provided for other adults in the household to co-isolate with the vulnerable individual. Solid organ transplant recipients are at the highest risk; vaccination of household contacts should be considered for this group.

1 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article , trajectories of the coronavirus disease (COVID-19) pandemic in England and Scotland until November 2021 are studied. And the authors conclude that vaccination programmes may have contributed modestly to the acquisition of herd immunity in populations with high levels of pre-existing naturally acquired immunity, while being crucial to protect vulnerable individuals from severe outcomes as the virus becomes endemic.

48 citations

Posted ContentDOI
11 Feb 2022-medRxiv
TL;DR: The cohort analysis does not support a causal effect of SARS-CoV-2 infection itself on T1DM incidence, but in those aged 0-14 years incidence of T1 DM during 2020-2021 was 20% higher than the 7-year average.
Abstract: Background Studies using claims databases have reported that SARS-CoV-2 infection >30 days earlier increased the incidence of type 1 diabetes (T1DM). Using exact dates of type 1 diabetes diagnosis from the national register in Scotland linked to virology laboratory data we sought to replicate this finding. Methods A cohort of 1849411 individuals aged <35 years without diabetes, including all those of this age in Scotland who subsequently tested positive for SARS-CoV-2, was followed from 1 March 2020 to 22 November 2021. Incident T1DM was identified by linkage to the national registry. Cox regression was used to test the association of time-updated infection with incident T1DM. Trends in incidence of T1DM in the total population from 2015-2021 were estimated in a generalized additive model. Results There were 365080 in the cohort with at least one detected SARS-CoV-2 infection during follow-up and 1074 who developed T1DM. The rate ratio for incident T1DM associated with first positive test for SARS-CoV-2 (with no previous infection as reference category) was 0.88 (95% CI 0.63 to 1.23) for infection more than 30 days earlier and 2.62 (95% CI 1.81 to 3.79) for infection in the previous 30 days. However negative and positive SARS-CoV-2 tests were more frequent in the days surrounding T1DM presentation. In those aged 0-14 years incidence of T1DM during 2020-2021 was 20% higher than the 7-year average. Conclusions T1DM incidence in children increased during the pandemic. However the cohort analysis does not support a causal effect of SARS-CoV-2 infection itself on T1DM incidence.

32 citations

Journal ArticleDOI
TL;DR: In this article , the authors reported that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection 30 days earlier was associated with an increase in the incidence of type 1 diabetes.
Abstract: OBJECTIVE Studies using claims databases reported that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection &gt;30 days earlier was associated with an increase in the incidence of type 1 diabetes. Using exact dates of diabetes diagnosis from the national register in Scotland linked to virology laboratory data, we sought to replicate this finding. RESEARCH DESIGN AND METHODS A cohort of 1,849,411 individuals aged &lt;35 years without diabetes, including all those in Scotland who subsequently tested positive for SARS-CoV-2, was followed from 1 March 2020 to 22 November 2021. Incident type 1 diabetes was ascertained from the national registry. Using Cox regression, we tested the association of time-updated infection with incident diabetes. Trends in incidence of type 1 diabetes in the population from 2015 through 2021 were also estimated in a generalized additive model. RESULTS There were 365,080 individuals who had at least one detected SARS-CoV-2 infection during follow-up and 1,074 who developed type 1 diabetes. The rate ratio for incident type 1 diabetes associated with first positive test for SARS-CoV-2 (reference category: no previous infection) was 0.86 (95% CI 0.62, 1.21) for infection &gt;30 days earlier and 2.62 (95% CI 1.81, 3.78) for infection in the previous 30 days. However, negative and positive SARS-CoV-2 tests were more frequent in the days surrounding diabetes presentation. In those aged 0–14 years, incidence of type 1 diabetes during 2020–2021 was 20% higher than the 7-year average. CONCLUSIONS Type 1 diabetes incidence in children increased during the pandemic. However, the cohort analysis suggests that SARS-CoV-2 infection itself was not the cause of this increase.

25 citations

Journal ArticleDOI
TL;DR: In this paper , a stochastic individual-based model of secondary school infection was used to quantify pupil-to-pupil SARS-CoV-2 transmission and the impact of implemented control measures.
Abstract: A range of measures have been implemented to control within-school SARS-CoV-2 transmission in England, including the self-isolation of close contacts and twice weekly mass testing of secondary school pupils using lateral flow device tests (LFTs). Despite reducing transmission, isolating close contacts can lead to high levels of absences, negatively impacting pupils. To quantify pupil-to-pupil SARS-CoV-2 transmission and the impact of implemented control measures, we fit a stochastic individual-based model of secondary school infection to both swab testing data and secondary school absences data from England, and then simulate outbreaks from 31st August 2020 until 23rd May 2021. We find that the pupil-to-pupil reproduction number, Rschool, has remained below 1 on average across the study period, and that twice weekly mass testing using LFTs has helped to control pupil-to-pupil transmission. We also explore the potential benefits of alternative containment strategies, finding that a strategy of repeat testing of close contacts rather than isolation, alongside mass testing, substantially reduces absences with only a marginal increase in pupil-to-pupil transmission.

21 citations