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1.
International Journal of Infectious Diseases ; 2022.
Article in English | ScienceDirect | ID: covidwho-1983202

ABSTRACT

Objectives Seroprevalence studies can provide a measure of SARS-CoV-2 cumulative incidence, but a better understanding of spike (anti-S) and nucleocapsid (anti-N) antibody dynamics following infection is needed to assess longevity of detectability. Methods Adults aged ≥18 years old, from households enrolled in the Virus Watch prospective community cohort study in England and Wales, provided monthly capillary-blood samples which were tested for anti-S and anti-N. Participants self-reported vaccination dates and past medical history. Prior polymerase chain reaction (PCR) swabs were obtained through Second Generation Surveillance System (SGSS) linkage data. Primary outcome variables were seropositivity and total anti-N and anti-S levels after PCR confirmed infection. Results A total of 13,802 eligible individuals provided 58,770 capillary blood samples. 537 of these had a prior positive PCR confirmed SARS-CoV-2 infection within 0-269 days of antibody sample date, with 432 (80.45%) having a positive anti-N result. Median anti-N levels peaked between days 90 and 119 post PCR results and then began to decline. There is evidence of anti-N waning from 120 days onwards, with earlier waning for females and younger age categories. Conclusion Our findings suggests that anti-N have around 80% sensitivity for identifying previous COVID-19 infection and duration of detectability is affected by sex and age.

2.
Occup Environ Med ; 2022 Apr 21.
Article in English | MEDLINE | ID: covidwho-1807493

ABSTRACT

OBJECTIVES: Risk of SARS-CoV-2 infection varies across occupations; however, investigation into factors underlying differential risk is limited. We aimed to estimate the total effect of occupation on SARS-CoV-2 serological status, whether this is mediated by workplace close contact, and how exposure to poorly ventilated workplaces varied across occupations. METHODS: We used data from a subcohort (n=3775) of adults in the UK-based Virus Watch cohort study who were tested for SARS-CoV-2 anti-nucleocapsid antibodies (indicating natural infection). We used logistic decomposition to investigate the relationship between occupation, contact and seropositivity, and logistic regression to investigate exposure to poorly ventilated workplaces. RESULTS: Seropositivity was 17.1% among workers with daily close contact vs 10.0% for those with no work-related close contact. Compared with other professional occupations, healthcare, indoor trade/process/plant, leisure/personal service, and transport/mobile machine workers had elevated adjusted total odds of seropositivity (1.80 (1.03 to 3.14) - 2.46 (1.82 to 3.33)). Work-related contact accounted for a variable part of increased odds across occupations (1.04 (1.01 to 1.08) - 1.23 (1.09 to 1.40)). Occupations with raised odds of infection after accounting for work-related contact also had greater exposure to poorly ventilated workplaces. CONCLUSIONS: Work-related close contact appears to contribute to occupational variation in seropositivity. Reducing contact in workplaces is an important COVID-19 control measure.

3.
Lancet Reg Health Eur ; 16: 100352, 2022 May.
Article in English | MEDLINE | ID: covidwho-1799798

ABSTRACT

Background: Workplaces are an important potential source of SARS-CoV-2 exposure; however, investigation into workplace contact patterns is lacking. This study aimed to investigate how workplace attendance and features of contact varied between occupations across the COVID-19 pandemic in England. Methods: Data were obtained from electronic contact diaries (November 2020-November 2021) submitted by employed/self-employed prospective cohort study participants (n=4,616). We used mixed models to investigate the effects of occupation and time for: workplace attendance, number of people sharing workspace, time spent sharing workspace, number of close contacts, and usage of face coverings. Findings: Workplace attendance and contact patterns varied across occupations and time. The predicted probability of intense space sharing during the day was highest for healthcare (78% [95% CI: 75-81%]) and education workers (64% [59%-69%]), who also had the highest probabilities for larger numbers of close contacts (36% [32%-40%] and 38% [33%-43%] respectively). Education workers also demonstrated relatively low predicted probability (51% [44%-57%]) of wearing a face covering during close contact. Across all occupational groups, workspace sharing and close contact increased and usage of face coverings decreased during phases of less stringent restrictions. Interpretation: Major variations in workplace contact patterns and mask use likely contribute to differential COVID-19 risk. Patterns of variation by occupation and restriction phase may inform interventions for future waves of COVID-19 or other respiratory epidemics. Across occupations, increasing workplace contact and reduced face covering usage is concerning given ongoing high levels of community transmission and emergence of variants. Funding: Medical Research Council; HM Government; Wellcome Trust.

4.
Wellcome Open Res ; 6: 224, 2021.
Article in English | MEDLINE | ID: covidwho-1780277

ABSTRACT

Introduction: Increased transmissibility of B.1.1.7 variant of concern (VOC) in the UK may explain its rapid emergence and global spread. We analysed data from putative household infector - infectee pairs in the Virus Watch Community cohort study to assess the serial interval of COVID-19 and whether this was affected by emergence of the B.1.1.7 variant. Methods: The Virus Watch study is an online, prospective, community cohort study following up entire households in England and Wales during the COVID-19 pandemic. Putative household infector-infectee pairs were identified where more than one person in the household had a positive swab matched to an illness episode. Data on whether or not individual infections were caused by the B.1.1.7 variant were not available. We therefore developed a classification system based on the percentage of cases estimated to be due to B.1.1.7 in national surveillance data for different English regions and study weeks. Results: Out of 24,887 illnesses reported, 915 tested positive for SARS-CoV-2 and 186 likely 'infector-infectee' pairs in 186 households amongst 372 individuals were identified. The mean COVID-19 serial interval was 3.18 (95%CI: 2.55 - 3.81) days. There was no significant difference (p=0.267) between the mean serial interval for VOC hotspots (mean = 3.64 days, (95%CI: 2.55 - 4.73)) days and non-VOC hotspots, (mean = 2.72 days, (95%CI: 1.48 - 3.96)). Conclusions: Our estimates of the average serial interval of COVID-19 are broadly similar to estimates from previous studies and we find no evidence that B.1.1.7 is associated with a change in serial intervals.  Alternative explanations such as increased viral load, longer period of viral shedding or improved receptor binding may instead explain the increased transmissibility and rapid spread and should undergo further investigation.

5.
EuropePMC; 2022.
Preprint in English | EuropePMC | ID: ppcovidwho-332465

ABSTRACT

Background: Respiratory viruses, including SARS-CoV-2, can infect the eyes or pass into the nose via the nasolacrimal duct. The importance of transmission via the eyes is unknown but might plausibly be reduced in those who wear glasses. Previous studies have mainly focussed on protective eyewear in healthcare settings. Methods Participants from the Virus Watch prospective community cohort study in England and Wales responded to a questionnaire on the use of glasses and contact lenses. This included frequency of use, purpose, and likelihood of wearing a mask with glasses. Infection was confirmed through data linkage with Second Generation Surveillance System (Pillar 1 and Pillar 2), weekly questionnaires to self-report positive polymerase chain reaction or lateral flow results, and, for a subgroup, monthly capillary blood testing for antibodies (nucleocapsid and spike). A multivariable logistic regression model, controlling for age, sex, income and occupation, was used to identify odds of infection depending on the frequency and purpose of using glasses or contact lenses. Findings 19,166 Virus Watch participants responded to the questionnaire, with 13,681 (71.3%, CI 70.7-72.0) reporting they wore glasses. A multivariable logistic regression model showed a 15% lower odds of infection for those who reported using glasses always for general use (OR 0.85, 95% 0.77-0.95, p = 0.002) compared to those who never wore glasses. The protective effect was reduced in those who said that wearing glasses interfered with mask wearing. No protective effect was seen for contact lens wearers. Interpretation People who wear glasses have a moderate reduction in risk of COVID-19 infection highlighting the importance of the eye as a route of infection. Eye protection may make a valuable contribution to the reduction of transmission in community and healthcare settings.

6.
EuropePMC; 2022.
Preprint in English | EuropePMC | ID: ppcovidwho-330045

ABSTRACT

Background: Understanding symptomatology and accuracy of clinical case definitions for community COVID-19 cases is important for Test, Trace and Isolate (TTI) and future targeting of early antiviral treatment.   Methods: : Community cohort participants prospectively recorded daily symptoms and swab results (mainly undertaken through the UK TTI system).  We compared symptom frequency, severity, timing, and duration in test positive and negative illnesses.  We compared the test performance of the current UK TTI case definition (cough, high temperature, or loss of or altered sense of smell or taste) with a wider definition adding muscle aches, chills, headache, or loss of appetite.     Results: : Among 9706 swabbed illnesses, including 973 SARS-CoV-2 positives, symptoms were more common, severe and longer lasting in swab positive than negative illnesses.  Cough, headache, fatigue, and muscle aches were the most common symptoms in positive illnesses but also common in negative illnesses. Conversely, high temperature, loss or altered sense of smell or taste and loss of appetite were less frequent in positive illnesses, but comparatively even less frequent in negative illnesses.  The current UK definition had 81% sensitivity and 47% specificity versus 93% and 27% respectively for the broader definition. 1.7-fold more illnesses met the broader case definition than the current definition.  Conclusions: : Symptoms alone cannot reliably distinguish COVID-19 from other respiratory illnesses. Adding additional symptoms to case definitions could identify more infections, but with a large increase in the number needing testing and the number of unwell individuals and contacts self-isolating whilst awaiting results.

7.
EuropePMC;
Preprint in English | EuropePMC | ID: ppcovidwho-327349

ABSTRACT

Introduction: Seroprevalence studies can provide a measure of cumulative incidence of SARS-CoV-2 infection, but a better understanding of antibody dynamics following infection is needed to assess longevity of detectability. Infection is characterised by detection of spike (anti-S) and nucleocapsid (anti-N) antibodies, whereas vaccination only stimulates anti-S. Consequently, in the context of a highly vaccinated population, presence of anti-N can be used as a marker of previous infection but waning over time may limit its use. Methods: Adults aged 18 years and older, from households enrolled in the Virus Watch prospective community cohort study in England and Wales, provided monthly capillary blood samples which were tested for anti-S and anti-N. Participants self-reported vaccination dates and past medical history. Prior polymerase chain reaction (PCR) swabs were obtained through Second Generation Surveillance System (SGSS) linkage data. Primary outcome variables were seropositivity (antibodies at or above the manufacturer's cut-off for positivity) and total anti-N and anti-S levels after PCR confirmed infection. Outcomes were analysed by days since infection, self-reported demographic and clinical factors. Results: A total of 13,802 eligible individuals, median age 63, provided 58,770 capillary blood samples. 537 of these had a prior positive PCR confirmed SARS-CoV-2 infection 0-269 days before the antibody sample date. 432 out of the 537 (80.44%) were anti-N positive and detection remained stable through-out follow-up. Median anti-N levels peaked between days 90 and 119 post PCR results and then began to decline. Logistic regression models, both univariable and multivariable, only showed higher odds of positive anti-N result between 0-269 days for 35-49 year olds, compared to 18-34 year olds. There is evidence of anti-N waning from 120 days onwards, with earlier waning for females and younger age categories. Discussion: Approximately 4 in 5 participants with prior PCR-confirmed infection were anti-N positive, and this remained stable through follow-up for at least 269 days. However, median antibody levels began to decline from about 120 days post-infection. This suggests that anti-N have around 80% sensitivity for identifying previous COVID-19 infection and that this sensitivity is maintained through 269 days of follow up.

8.
EuropePMC;
Preprint in English | EuropePMC | ID: ppcovidwho-327279

ABSTRACT

Background: It is poorly understood which workers lack access to sick pay in England and Wales. This evidence gap has been of particular interest in the context of the Covid-19 epidemic given the relationship between presenteeism and infectious disease transmission. Method: This cross-sectional analysis is nested within a large community cohort study of Covid-19 epidemiology in England and Wales (Virus Watch). An online survey in February 2021 asked participants if they had access to paid sick leave. We use a fixed effect logistic regression model to examine sociodemographic factors associated with lacking access to sick pay. Results: 8,874 participants in work responded to the survey item about access to sick pay. Of those, 5,864 (66%) report having access to sick pay, 2,218 (25%) report no access to sick pay and 792 (8.9%) were unsure. Workers aged 45-64 (OR 1.72) and over 65 (OR 5.26) are more likely to lack access to sick pay compared to workers aged 25-44. South Asian workers (OR 1.40) and those from Other minority ethnic backgrounds (OR 2.93) are more likely to lack access to sick pay compared to White British workers. Workers in low income households (OR 1.43-2.53) and those with working class occupations (OR 2.04-5.29) are also more likely to lack access to sick pay compared to those in high income households and managerial occupations. Discussion: Unwarranted age and race inequalities in sick pay access are suggestive of labour market discrimination. Occupational differences are also cause for concern. Policymakers should consider expanding access to sick pay to mitigate transmission of Covid-19 and other endemic infectious disease epidemics in the community.

9.
EuropePMC; 2021.
Preprint in English | EuropePMC | ID: ppcovidwho-306539

ABSTRACT

We aimed to assess the relative importance of different settings for SARS-CoV-2 transmission in a large community cohort based on perceived location of infection for self-reported confirmed SARS-COV-2 cases. We demonstrate the importance of home, work and education as perceived venues for transmission. In children, education was most important and in older adults essential shopping was of high importance.  Our findings support public health messaging about infection control at home, advice on working from home and restrictions in different venues.

10.
EuropePMC; 2021.
Preprint in English | EuropePMC | ID: ppcovidwho-310991

ABSTRACT

Introduction: Increased transmissibility of B.1.1.7 variant of concern (VOC) in the UK may explain its rapid emergence and global spread. We analysed data from putative household infector - infectee pairs in the Virus Watch Community cohort study to assess the serial interval of COVID-19 and whether this was affected by emergence of the B.1.1.7 variant. Methods: The Virus Watch study is an online, prospective, community cohort study following up entire households in England and Wales during the COVID-19 pandemic. Putative household infector-infectee pairs were identified where more than one person in the household had a positive swab matched to an illness episode. Data on whether or not individual infections were caused by the B.1.1.7 variant were not available. We therefore developed a classification system based on the percentage of cases estimated to be due to B.1.1.7 in national surveillance data for different English regions and study weeks. Results: Out of 24,887 illnesses reported, 915 tested positive for SARS-CoV-2 and 186 likely ‘infector-infectee’ pairs in 186 households amongst 372 individuals were identified. The mean COVID-19 serial interval was 3.18 (95%CI: 2.55 - 3.81) days. There was no significant difference (p=0.267) between the mean serial interval for VOC hotspots (mean = 3.64 days, (95%CI: 2.55 – 4.73)) days and non-VOC hotspots, (mean = 2.72 days, (95%CI: 1.48 – 3.96)). Conclusions: Our estimates of the average serial interval of COVID-19 are broadly similar to estimates from previous studies and we find no evidence that B.1.1.7 is associated with a change in serial intervals.  Alternative explanations such as increased viral load, longer period of viral shedding or improved receptor binding may instead explain the increased transmissibility and rapid spread and should undergo further investigation.

11.
EuropePMC;
Preprint in English | EuropePMC | ID: ppcovidwho-327509

ABSTRACT

The two most commonly-used SARS-CoV-2 vaccines in the UK, BNT162b2 (Pfizer-BioNTech) and ChAdOx1 nCoV-19 (Oxford-AstraZeneca), employ different immunogenic mechanisms. Compared to BNT162b2, two-dose immunisation with ChAdOx1 induces substantially lower peak anti-spike antibody (anti-S) levels and is associated with a higher risk of breakthrough infections. To provide preliminary indication of how a third booster BNT162b2 dose impacts anti-S levels, we performed a cross-sectional analysis using capillary blood samples from vaccinated adults (aged ≥18 years) participating in Virus Watch, a prospective community cohort study in England and Wales. Blood samples were analysed using Roche Elecsys Anti-SARS-CoV-2 S immunoassay. We analysed anti-S levels by week since the third dose for vaccines administered on or after September 1, 2021 and stratified the results by second dose vaccine type (ChAdOx1 or BNT162b2), age, sex and clinical vulnerability. Anti-S levels peaked at two weeks post-booster for BNT162b2 (22,185 U/mL;95%CI: 21,406-22,990) and ChAdOx1 second dose recipients (19,203 U/mL;95%CI: 18,094-20,377). These were higher than the corresponding peak antibody levels post-second dose for BNT162b2 (12,386 U/mL;95%CI: 9,801-15,653, week 2) and ChAdOx1 (1,192 U/mL;95%CI: 818-1735, week 3). No differences emerged by second dose vaccine type, age, sex or clinical vulnerability. Anti-S levels declined post-booster for BNT162b2 (half-life=44 days) and ChAdOx1 second dose recipients (half-life=40 days). These rates of decline were steeper than those post-second dose for BNT162b2 (half-life=54 days) and ChAdOx1 (half-life=80 days). Our findings suggest that peak anti-S levels are higher post-booster than post-second dose, but that levels are projected to be similar after six months for BNT162b2 recipients. Higher peak anti-S levels post-booster may partially explain the increased effectiveness of booster vaccination compared to two-dose vaccination against symptomatic infection with the Omicron variant. Faster waning trajectories post third-dose may have implications for the timing of future booster campaigns or four-dose vaccination regimens for the clinically vulnerable.

12.
EuropePMC;
Preprint in English | EuropePMC | ID: ppcovidwho-327441

ABSTRACT

Importance The Omicron (B.1.1.529) variant has increased SARs-CoV-2 infections in double vaccinated individuals globally, particularly in ChAdOx1 recipients. To tackle rising infections, the UK accelerated booster vaccination programmes used mRNA vaccines irrespective of an individual’s primary course vaccine type with booster doses rolled out according to clinical priority. There is limited understanding of the effectiveness of different primary vaccination courses on mRNA based booster vaccines against SARs-COV-2 infections and how time-varying confounders can impact the evaluations comparing different vaccines as primary courses for mRNA boosters. Objective To evaluate the comparative effectiveness of ChAdOx1 versus BNT162b2 as primary doses against SARs-CoV-2 in booster vaccine recipients whilst accounting for time-varying confounders. Design Trial emulation was used to reduce time-varying confounding-by-indication driven by prioritising booster vaccines based upon age, vulnerability and exposure status e.g. healthcare worker. Trial emulation was conducted by meta-analysing eight cohort results whose booster vaccinations were staggered between 16/09/2021 to 05/01/2022 and followed until 23/01/2022. Time from booster vaccination until SARS-CoV-2 infection, loss of follow-up or end-of-study was modelled using Cox proportional hazards models for each cohort and adjusted for age, sex, minority ethnic status, clinically vulnerability, and deprivation. Setting Prospective observational study using the Virus Watch community cohort in England and Wales. Participants People over the age of 18 years who had their booster vaccination between 16/09/2021 to 05/01/2022 without prior natural immunity. Exposures ChAdOx1 versus BNT162b2 as a primary dose, and an mRNA booster vaccine. Results Across eight cohorts, 19,692 mRNA vaccine boosted participants were analysed with 12,036 ChAdOx1 and 7,656 BNT162b2 primary courses with a median follow-up time of 73 days (IQR:54-90). Median age, clinical vulnerability status and infection rates fluctuate through time. 7.2% (n=864) of boosted adults with ChAdOx1 primary course experienced a SARS-CoV-2 infection compared to 7.6% (n=582) of those with BNT162b2 primary course during follow-up. The pooled adjusted hazard ratio was 0.99 [95%CI:0.88-1.11], demonstrating no difference between the incidence of SARs-CoV-2 infections based upon the primary vaccine course. Conclusion and Relevance In mRNA boosted individuals, we found no difference in protection comparing those with a primary course of BNT162b2 to those with aChAdOx1 primary course. This contrasts with pre-booster findings where previous research shows greater effectiveness of BNT162b2 than ChAdOx1 in preventing infection.

13.
EuropePMC; 2021.
Preprint in English | EuropePMC | ID: ppcovidwho-296537

ABSTRACT

Background: Workplaces are an important potential source of SARS-CoV-2 exposure;however, investigation into workplace contact patterns is lacking. This study aimed to investigate how workplace attendance and features of contact varied between occupations and over time during the COVID-19 pandemic in England. Methods: Data were obtained from electronic contact diaries submitted between November 2020 and November 2021 by employed/self-employed prospective cohort study participants (n=4,616). We used mixed models to investigate the main effects and potential interactions between occupation and time for: workplace attendance, number of people in shared workspace, time spent sharing workspace, number of close contacts, and usage of face coverings. Findings: Workplace attendance and contact patterns varied across occupations and time. The predicted probability of intense space sharing during the day was highest for healthcare (78% [95% CI: 75-81%]) and education workers (64% [59%-69%]), who also had the highest probabilities for larger numbers of close contacts (36% [32%-40%] and 38% [33%-43%] respectively). Education workers also demonstrated relatively low predicted probability (51% [44%-57%]) of wearing a face covering during close contact. Across all occupational groups, levels of workspace sharing and close contact were higher and usage of face coverings at work lower in later phases of the pandemic compared to earlier phases. Interpretation: Major variations in patterns of workplace contact and mask use are likely to contribute to differential COVID-19 risk. Across occupations, increasing workplace contact and reduced usage of face coverings presents an area of concern given ongoing high levels of community transmission and emergence of variants.

14.
EuropePMC; 2021.
Preprint in English | EuropePMC | ID: ppcovidwho-296536

ABSTRACT

Background: Workers differ in their risk of SARS-CoV-2 infection according to their occupation, but the direct contribution of occupation to this relationship is unclear. This study aimed to investigate how infection risk differed across occupational groups in England and Wales up to October 2021, after adjustment for potential confounding and stratification by pandemic phase. Methods: Data from 12,182 employed/self-employed participants in the Virus Watch prospective cohort study were used to generate risk ratios for virologically- or serologically-confirmed SARS-CoV-2 infection using robust Poisson regression, adjusting for socio-demographic and health-related factors and non-work public activities. We calculated attributable fractions (AF) amongst the exposed for each occupational group based on adjusted risk ratios (aRR). Findings: Increased risk was seen in nurses (aRR=1.90 [1.40-2.40], AF=47%);doctors (1.74 [1.26-2.40], 42%);carers (2.18 [1.63-2.92], 54%);teachers (primary = 1.94 [1.44- 2.61], 48%;secondary =1.64, [1.23-2.17], 39%), and warehouse and process/plant workers (1.58 [1.20-2.09], 37%) compared to both office-based professional occupations (reported above) and all other occupations. Differential risk was apparent in the earlier phases (Feb 2020 - May 2021) and attenuated later (June - October 2021) for most groups, although teachers demonstrated persistently elevated risk. Interpretation: Occupational differentials in SARS-CoV-2 infection risk are robust to adjustment for socio-demographic, health-related, and activity-related potential confounders. Patterns of differential infection risk varied over time, and ongoing excess risk was observed in education professionals. Direct investigation into workplace factors underlying elevated risk and how these change over time is needed to inform occupational health interventions.

15.
EuropePMC; 2021.
Preprint in English | EuropePMC | ID: ppcovidwho-296511

ABSTRACT

Background: Household overcrowding is associated with increased risk of infectious diseases across contexts and countries. Limited data exist linking household overcrowding and risk of COVID-19. We used data collected from the Virus Watch cohort to examine the association between overcrowded households and SARS-CoV-2. Methods: The Virus Watch study is a household community cohort of acute respiratory infections in England and Wales. We calculated overcrowding using the measure of persons per room for each household. We considered two primary outcomes: PCR-confirmed positive SARS-CoV-2 antigen tests and laboratory-confirmed SARS-CoV-2 antibodies. We used mixed-effects logistic regression models that accounted for household structure to estimate the association between household overcrowding and SARS-CoV-2 infection. Results: 26,367 participants were included in our analyses. The proportion of participants with a positive SARS-CoV-2 PCR result was highest in the overcrowded group (9.0%;99/1,100) and lowest in the under-occupied group (4.2%;980/23,196). In a mixed-effects logistic regression model, we found strong evidence of an increased odds of a positive PCR SARS-CoV-2 antigen result (odds ratio 2.45;95% CI:1.43–4.19;p-value=0.001) and increased odds of a positive SARS-CoV-2 antibody result in individuals living in overcrowded houses (3.32;95% CI:1.54–7.15;p-value<0.001) compared with people living in under-occupied houses. Conclusion: Public health interventions to prevent and stop the spread of SARS-CoV-2 should consider the risk of infection for people living in overcrowded households and pay greater attention to reducing household transmission.

16.
2021.
Preprint in English | Other preprints | ID: ppcovidwho-296012

ABSTRACT

Background Vaccination constitutes the best long-term solution against Coronavirus Disease 2019 (COVID-19). Real-world immunogenicity data are sparse, particularly for ChAdOx1 and in populations with chronic conditions;and given the UK’s extended dosing interval, it is also important to understand antibody responses in SARS-CoV-2-naive individuals following a single dose. Methods Adults aged ≥18 years from households enrolled in Virus Watch, a prospective community cohort study in England and Wales, provided capillary blood samples and self-reported vaccination status. Primary outcome variables were quantitative Spike total antibody levels (U/ml) and seropositivity to Spike (≥0.8 U/ml), as per Roche’s Elecsys Anti-SARS-CoV-2 S assay. Samples seropositive for Nucleocapsid, and samples taken prior to vaccination, were excluded. Outcomes were analysed by days since vaccination, vaccine type (BNT162b2 and ChAdOx1), and a range of self-reported demographic and clinical factors. Results 8,837 vaccinated participants (median age 65 years [IQR: 58, 71]), contributed 17,160 samples (10,508 following ChAdOx1, 6,547 following BNT162b2). Seropositivity to Spike was 96.79% (95% CI 96.42, 97.12) from 28 days following a single dose, reaching 99.34% (98.91, 99.60) from 14 days after a second dose. Seropositivity rates, and Spike-antibody levels rose more quickly following the first dose of BNT162b2, however, were equivalent for both vaccines by 4 and 8 weeks, respectively. There was evidence for lower S-antibody levels with increasing age (p=0.0001). In partially vaccinated 65-79 year-olds, lower S-antibody levels were observed in men compared with women (26.50 vs 44.01 U/ml, p<0.0001), those with any chronic condition (33.8 vs 43.83 U/ml, p<0.0001), diabetes (22.46 vs 36.90 U/ml, p<0.0001), cardiovascular disease (32.9 vs 37.9 U/ml, p=0.0002), obesity (27.2 vs 37.42, p<0.0001), cancer diagnosis (31.39 vs 36.50 U/ml, p=0.0001), particularly those with haematological cancers (7.94 vs 32.50 U/ml, p<0.0001), and for those currently on statin therapy (30.03 vs 39.39, p<0.0001), or on any immunosuppressive therapy (28.7 vs 36.78 U/ml, p<0.0001), particularly those on oral steroids (16.8 vs 36.07, p<0.0001). Following a second dose, high S-antibody titres (≥250U/ml) were observed across all groups. Interpretation A single dose of either BNT162b2 or ChAdOx1 leads to high Spike seropositivity rates in SARS-CoV-2-naive individuals. Observed disparities in antibody levels by vaccine type, age, and comorbidities highlight the importance of ongoing non-pharmaceutical preventative measures for partially vaccinated adults, particularly those who are older and more clinically vulnerable;and high antibody levels across all groups following a second dose demonstrate the importance of complete vaccination. However, the relationship between Spike-antibody levels and protection against COVID-19, and thus the clinical significance of observed disparities, is not yet clear.

17.
J Epidemiol Community Health ; 76(4): 319-326, 2022 04.
Article in English | MEDLINE | ID: covidwho-1467721

ABSTRACT

BACKGROUND: Differential exposure to public activities may contribute to stark deprivation-related inequalities in SARS-CoV-2 infection and outcomes but has not been directly investigated. We set out to investigate whether participants in Virus Watch-a large community cohort study based in England and Wales-reported differential exposure to public activities and non-household contacts during the autumn-winter phase of the COVID-19 pandemic according to postcode-level socioeconomic deprivation. METHODS: Participants (n=20 120-25 228 across surveys) reported their daily activities during 3 weekly periods in late November 2020, late December 2020 and mid-February 2021. Deprivation was quantified based on participants' residential postcode using English or Welsh Index of Multiple Deprivation quintiles. We used Poisson mixed-effect models with robust standard errors to estimate the relationship between deprivation and risk of exposure to public activities during each survey period. RESULTS: Relative to participants in the least deprived areas, participants in the most deprived areas exhibited elevated risk of exposure to vehicle sharing (adjusted risk ratio (aRR) range across time points: 1.73-8.52), public transport (aRR: 3.13-5.73), work or education outside of the household (aRR: 1.09-1.21), essential shops (aRR: 1.09-1.13) and non-household contacts (aRR: 1.15-1.19) across multiple survey periods. CONCLUSION: Differential exposure to essential public activities-such as attending workplaces and visiting essential shops-is likely to contribute to inequalities in infection risk and outcomes. Public health interventions to reduce exposure during essential activities and financial and practical support to enable low-paid workers to stay at home during periods of intense transmission may reduce COVID-related inequalities.


Subject(s)
COVID-19 , COVID-19/epidemiology , Cohort Studies , England/epidemiology , Health Status Disparities , Humans , Pandemics , SARS-CoV-2 , Wales/epidemiology
18.
Vaccine ; 39(48): 7108-7116, 2021 11 26.
Article in English | MEDLINE | ID: covidwho-1458555

ABSTRACT

BACKGROUND: Vaccination intention is key to the success of any vaccination programme, alongside vaccine availability and access. Public intention to take a COVID-19 vaccine is high in England and Wales compared to other countries, but vaccination rate disparities between ethnic, social and age groups has led to concern. METHODS: Online survey of prospective household community cohort study participants across England and Wales (Virus Watch). Vaccination intention was measured by individual participant responses to 'Would you accept a COVID-19 vaccine if offered?', collected in December 2020 and February 2021. Responses to a 13-item questionnaire collected in January 2021 were analysed using factor analysis to investigate psychological influences on vaccination intention. RESULTS: Survey response rate was 56% (20,785/36,998) in December 2020 and 53% (20,590/38,727) in February 2021, with 14,880 adults reporting across both time points. In December 2020, 1,469 (10%) participants responded 'No' or 'Unsure'. Of these people, 1,266 (86%) changed their mind and responded 'Yes' or 'Already had a COVID-19 vaccine' by February 2021. Vaccination intention increased across all ethnic groups and levels of social deprivation. Age was most strongly associated with vaccination intention, with 16-24-year-olds more likely to respond "Unsure" or "No" versus "Yes" than 65-74-year-olds in December 2020 (OR: 4.63, 95 %CI: 3.42, 6.27 & OR 7.17 95 %CI: 4.26, 12.07 respectively) and February 2021 (OR: 27.92 95 %CI: 13.79, 56.51 & OR 17.16 95 %CI: 4.12, 71.55). The association between ethnicity and vaccination intention weakened, but did not disappear, over time. Both vaccine- and illness-related psychological factors were shown to influence vaccination intention. CONCLUSIONS: Four in five adults (86%) who were reluctant or intending to refuse a COVID-19 vaccine in December 2020 had changed their mind in February 2021 and planned to accept, or had already accepted, a vaccine.


Subject(s)
COVID-19 Vaccines , COVID-19 , Adult , Cohort Studies , England , Humans , Intention , Prospective Studies , SARS-CoV-2 , Vaccination , Wales/epidemiology
20.
BMJ Open ; 11(6): e048042, 2021 06 23.
Article in English | MEDLINE | ID: covidwho-1285085

ABSTRACT

INTRODUCTION: The coronavirus (COVID-19) pandemic has caused significant global mortality and impacted lives around the world. Virus Watch aims to provide evidence on which public health approaches are most likely to be effective in reducing transmission and impact of the virus, and will investigate community incidence, symptom profiles and transmission of COVID-19 in relation to population movement and behaviours. METHODS AND ANALYSIS: Virus Watch is a household community cohort study of acute respiratory infections in England and Wales and will run from June 2020 to August 2021. The study aims to recruit 50 000 people, including 12 500 from minority ethnic backgrounds, for an online survey cohort and monthly antibody testing using home fingerprick test kits. Nested within this larger study will be a subcohort of 10 000 individuals, including 3000 people from minority ethnic backgrounds. This cohort of 10 000 people will have full blood serology taken between October 2020 and January 2021 and repeat serology between May 2021 and August 2021. Participants will also post self-administered nasal swabs for PCR assays of SARS-CoV-2 and will follow one of three different PCR testing schedules based on symptoms. ETHICS AND DISSEMINATION: This study has been approved by the Hampstead National Health Service (NHS) Health Research Authority Ethics Committee (ethics approval number 20/HRA/2320). We are monitoring participant queries and using these to refine methodology where necessary, and are providing summaries and policy briefings of our preliminary findings to inform public health action by working through our partnerships with our study advisory group, Public Health England, NHS and government scientific advisory panels.


Subject(s)
COVID-19 , Guideline Adherence/statistics & numerical data , Patient Acceptance of Health Care/statistics & numerical data , Public Health , COVID-19/epidemiology , England/epidemiology , Humans , Prospective Studies , Risk Factors , State Medicine , Wales/epidemiology
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