ABSTRACT
Background Personal protective behaviours (PPBs) played a crucial role in limiting the spread of infection during the COVID-19 pandemic, yet adherence to these behaviours varied at population level. Understanding the factors influencing adherence to protective behaviours is important, as PPBs will be a critical part of the response in future pandemics. Using behavioural science, we investigated the influences on adherence to PPBs, focusing on face mask wearing, social distancing, and lateral flow testing (LFT). Methods Two online surveys, the first gathering data on mask wearing and social distancing, and the second on lateral flow testing, were conducted in July and August 2021 with a sample from England and Wales (N = 20,488 (survey 1) and N = 26,613 (survey 2)). The survey questions were designed based on the Capability, Opportunity, Motivation (COM-B) model of Behavior. Multivariate models were used to examine associations between identified influences and adoption of these protective behaviours. Results Most respondents reported wearing a face mask in public indoor places (88.5%) and maintaining a 1+ metre distance (86.8%) all or most of the time. After two doses of COVID-19 vaccine, social distancing decreased with 48.3% reporting meeting friends or family and 38.3% visiting indoor places more frequently. Motivation, Opportunity and Capability factors were significantly associated with increased odds of wearing a face covering and social distancing. Among individuals who indicated using an LFT (comprising 68% of the total sample), 50.4% reported engaging in routine testing. For those who had never used an LFT, the predominant reason cited was a perceived lack of necessity for testing (55.3%). Statistically significant associations were found between routine testing and accurate interpretation of test results across all LFT belief-based statements (p < 0.05). Conclusions Findings indicated high levels of adherence to face masks, social distancing, and lateral flow testing, even amid reduced restrictions and high vaccination rates. Utilising a behavioural science framework, factors related to capability, opportunity, and motivation were found to significantly influence the use of these protective behaviours. Our recommendations can inform public health intervention design and guide the selection of implementation strategies for public health emergencies preparedness.
Subject(s)
COVID-19ABSTRACT
BackgroundVirus Watch is a prospective community cohort study of COVID-19 of 28{square},527 households in England and Wales designed to estimate the incidence of PCR-confirmed COVID-19 in those with respiratory presentations and examine symptom profiles and transmission of COVID-19 in relation to population movement and behaviour. The Office for National Statistics (ONS) COVID-19 infection survey (CIS) was the largest regular survey of COVID-19 infections and antibodies in the UK and included 227,797 households. In this analysis, we aimed to compare incidence rate estimates from the two studies to understand differences in estimates from the two study designs. MethodsWe used the Virus Watch prospective community cohort study to estimate the overall SARS-CoV-2 incidence rate and incidence rate by age in England and Wales from June 2020 to February 2023. Virus Watch data consisted of self-reported laboratory COVID-19 test results and linkage to the Second Generation Surveillance System, the UK national database for COVID-19 testing. We compared our findings with modelled incidence rates from ONS CIS using 3-day rolling Pearsons correlation to measure synchrony. Results58,628 participants were recruited into the Virus Watch study between June 2020 and March 2022, of whom 52,526 (90%) were reported to be living in England and 1,532 (2.6%) in Wales. COVID-19 incidence rates were initially similar across age groups until the Delta wave when rates increased at different magnitudes. During the Omicron BA.1, the 0-14 age group had the highest incidence rates, which shifted to the 25-44 age group with Omicron BA.2, 4, and 5 dominance. We found strong synchrony between Virus Watch and ONS CIS COVID-19 incidence estimates for England and Wales, both with and without the incorporation of linked national testing data into the Virus Watch study. In particular, the magnitude and trend of Virus Watch- and ONS-estimated rates for England were generally consistent, although Virus Watch-estimated peaks of infection during the Omicron BA.1 and 2 waves were found to be lower than estimates from the ONS. ConclusionOur findings suggest that the Virus Watch research approach is a low-cost and effective method for on-going surveillance of COVID-19 regardless of the availability of national testing in the UK. Similar approaches can also be utilised by low-resource settings to provide accurate incidence rate estimates to better monitor and respond to COVID-19 as well as other acute respiratory diseases in the future.
Subject(s)
COVID-19 , Respiratory Tract DiseasesABSTRACT
BackgroundGiven the considerable prevalence of long-term sequelae following SARS-CoV-2 infection, understanding pathogen-related factors that influence long-term outcomes is warranted. We aimed to compare the likelihood of long-term symptoms for SARS-CoV-2 variants, other acute respiratory infections (ARIs) and non-infected individuals. MethodData were from 5,630 individuals participating in Virus Watch, a prospective community cohort study of SARS-CoV-2 epidemiology in England. We used logistic regression to compare the predicted probability of developing long-term symptoms (>2 months duration) during different variant dominance periods according to infection status (SARS-CoV-2, other ARI, or no infection), adjusting for confounding by demographic and clinical factors and vaccination status. ResultsPredicted probability of long-term sequelae was greater following SARS-CoV-2 infection during the Wild Type (adjusted predicted probability (PP) 0.28, 95% confidence interval (CI) =0.14-0.43), Alpha (PP= 0.28, 95% CI =0.14-0.42), Delta (PP= 0.34, 95% CI=0.25-0.43) and Omicron BA.1 periods (PP= 0.27, 95% CI =0.22-0.33) compared to later Omicron sub-variants (PP range from 0.11, 95% CI 0.08-0.15 to 0.14, 95% CI 0.10-0.18). While differences between SARS-CoV-2 and other ARIs (PP range 0.08, 95% CI 0.04-0.11 to 0.23, 95% CI 0.18-0.28) varied by period, estimates for long-term symptoms following both infection types substantially exceeded those for non-infected participants (PP range 0.01, 95% CI 0.00,0.02 to 0.03, 95% CI 0.01-0.06) across all variant periods. ConclusionsBetween-variant differences influenced the likelihood of post-infection sequelae for SARS-CoV-2, with lower predicted probabilities for recent Omicron sub-variants similar to those for other contemporaneous ARIs. Both SARS-CoV-2 and other ARIs were associated with long-term symptom development, and further aetiological investigation including between-pathogen comparison is recommended.
Subject(s)
COVID-19 , Respiratory Tract InfectionsABSTRACT
Due to the proliferation of new SARS-CoV-2 variants, most COVID-19 cases are now caused by post-vaccine infections and a substantial proportion are reinfections. While prior research on correlates of protection has focused on the role of anti-spike antibodies, the results of the corresponding antibody assays may not accurately predict the risk of infection with new SARS-CoV-2 variants. In this study, we investigated the association between live virus neutralising antibody activity and SARS-CoV-2 infection risk using self-administered capillary microsample blood tests from VirusWatch participants. The study was conducted during the transition between the dominance of the B.1.617.2 (Delta) and B.1.1.529 (Omicron BA.1) SARS-CoV-2 variants, enabling us to investigate the association between variant-specific virus inhibition and subsequent infections within each dominance period. Greater inhibition of Omicron BA.1 live virus was associated with a reduction in infection risk during both the Delta and Omicron BA.1 dominance periods. Delta virus inhibition was associated with infection risk reduction during the Delta dominance period, but we found no association between Delta inhibition and protection against infection during the Omicron BA.1 dominance period. Our results are consistent with earlier findings and suggest that variant-specific serosurveillance of immunity and protection against SARS-CoV-2 infection at the population level could inform public health policy in near-real time using inexpensive and accessible home-based testing.
Subject(s)
Severe Acute Respiratory Syndrome , COVID-19ABSTRACT
IntroductionEmerging evidence suggests association of air pollution exposure with risk of SARS-CoV-2 infection, but many of these findings are limited by study design, lack of individual-level covariate data or are specific to certain subpopulations. We aim to evaluate causal effects of air pollution on risk of infection, whilst overcoming these limitations. MethodsConcentrations for black carbon(BC), particulate matter 10(PM10), particulate matter 2.5(PM2.5), nitrogen dioxide(NO2) and oxides of nitrogen(NOx) from the Department of Environment, Food and Rural Affairs (DEFRA) and Effect of Low-level Air Pollution: A Study in Europe (ELAPSE) were linked to postcodes of 53,683 Virus Watch study participants. The primary outcome was first SARS-CoV-2 infection, between 1st September 2020 and 30th April 2021. Regression analysis used modified Poisson with robust estimates, clustered by household, adjusting for individual (e.g., age, sex, ethnicity) and environmental covariates(e.g., population density, region) to estimate total and direct effects. ResultsSingle pollutant analysis showed the direct effect of higher risk of SARS-CoV-2 infection with increased exposure to PM2.5(RR1.11,95%CI 1.08;1.15), PM10(RR1.06,95%CI 1.04;1.09), NO2(RR1.04,95%CI 1.04;1.05) and NOx(RR1.02,95%CI 1.02;1.02) per 1{micro}g/m3 increment with DEFRA 2015-19 data. Sensitivity analyses altering covariates, exposure window and modelled air pollution data source produced similar estimates. Higher risk of SARS-CoV-2 per 10-5m-1 increment of BC (RR1.86, 95%CI 1.62;2.14) was observed using ELAPSE data. ConclusionLong term exposure to higher concentrations of air pollutions increases the risk of SARS-CoV-2 infection, highlighting that adverse health effects of air pollution is not only limited to non-communicable diseases.
Subject(s)
COVID-19ABSTRACT
Introduction: The PROTECT National Core Study was funded by the UK Health and Safety Executive (HSE) to investigate routes of transmission for SARS-CoV-2 and variation between settings. Methods: A workshop was organised in Oct 2022.We brought together evidence from five published epidemiological studies that compared risks of SARS-CoV-2 infection or COVID-19 mortality by occupation or sector funded by PROTECT relating to three non-overlapping data sets, plus additional unpublished analyses relating to the Omicron period. We extracted descriptive study level data and model results. We investigated risk across four pandemic waves using forest plots for key occupational groups by time-period. Results: Results were largely consistent across different studies with different expected biases. Healthcare and social care sectors saw elevated risks of SARS-CoV-2 infection and COVID-19 mortality early in the pandemic, but thereafter this declined and varied by specific occupational subgroup. The education sector saw sustained elevated risks of infection after the initial lockdown period with little evidence of elevated mortality. Conclusions: Increased in risk of infection and mortality were consistently observed for occupations in high risk sectors particularly during the early stage of the pandemic. The education sector showed a different pattern compared to the other high risk sectors, as relative risk of infections remained high in the later phased of the pandemic, although no increased in COVID-19 mortality (compared to low-risk occupations) was observed in this sector in any point during the pandemic.
Subject(s)
COVID-19ABSTRACT
[bullet] Virus Watch is a national community cohort study of COVID-19 in households in England and Wales, established in June 2020. The study aims to provide evidence on which public health approaches are most effective in reducing transmission, and investigate community incidence, symptoms, and transmission of COVID-19 in relation to population movement and behaviours. [bullet] 28,527 households and 58,628 participants of age (0-98 years, mean age 48), were recruited between June 2020 - July 2022 [bullet] Data collected include demographics, details on occupation, co-morbidities, medications, and infection-prevention behaviours. Households are followed up weekly with illness surveys capturing symptoms and their severity, activities in the week prior to symptom onset and any COVID-19 test results. Monthly surveys capture household finance, employment, mental health, access to healthcare, vaccination uptake, activities and contacts. Data have been linked to Hospital Episode Statistics (HES), inpatient and critical care episodes, outpatient visits, emergency care contacts, mortality, virology testing and vaccination data held by NHS Digital. [bullet] Nested within Virus Watch are a serology & PCR cohort study (n=12,877) and a vaccine evaluation study (n=19,555). [bullet] Study data are deposited in the Office of National Statistics (ONS) Secure Research Service (SRS). Survey data are available under restricted access upon request to ONS SRS.
Subject(s)
COVID-19ABSTRACT
Background: Migrants in the UK may be at higher risk of SARS-CoV-2 exposure; however, little is known about their risk of COVID-19-related hospitalisation during waves 1-3 of the pandemic. Methods: We analysed secondary care data linked to Virus Watch study data for adults and estimated COVID-19-related hospitalisation incidence rates by migration status. To estimate the total effect of migration status on COVID-19 hospitalisation rates, we ran fixed-effect Poisson regression for wave 1 (01/03/2020-31/08/2020; wildtype), and fixed-effect negative binomial regressions for waves 2 (01/09/2020-31/05/2021; Alpha) and 3 (01/06/2020-31/11/2021; Delta). Results of all models were then meta-analysed. Results: Of 30,276 adults in the analyses, 26,492 (87.5%) were UK-born and 3,784 (12.5%) were migrants. COVID-19-related hospitalisation incidence rates for UK-born and migrant individuals across waves 1-3 were 2.7 [95% CI 2.2-3.2], and 4.6 [3.1-6.7] per 1,000 person-years, respectively. Pooled incidence rate ratios across waves suggested increased rate of COVID-19-related hospitalisation in migrants compared to UK-born individuals in unadjusted 1.68 [1.08-2.60] and adjusted analyses 1.35 [0.71-2.60]. Conclusions: Our findings suggest migration populations in the UK have excess risk of COVID-19-related hospitalisations and underscore the need for more equitable interventions particularly aimed at COVID-19 vaccination uptake among migrants.
Subject(s)
COVID-19ABSTRACT
Background: Migrants are over-represented in severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infections globally; however, evidence is limited for migrants in England and Wales. Household overcrowding is a risk factor for SARS-CoV-2 infection, with migrants more likely to live in overcrowded households than UK-born individuals. We aimed to estimate the total effect of migration status on SARS-CoV-2 infection and to what extent household overcrowding mediated this effect. Methods: We included a sub-cohort of individuals from the Virus Watch prospective cohort study during the second SARS-CoV-2 wave (1st September 2020-30th April 2021) who were aged at least 18 years, self-reported the number of rooms in their household and had no evidence of SARS-CoV-2 infection pre-September 2020. We estimated total, indirect and direct effects using Buis logistic decomposition regression controlling for age, sex, ethnicity, clinical vulnerability, occupation, income and whether they lived with children. Results: In total, 23,478 individuals were included. 9.07% (187/2,062) of migrants had evidence of infection during the study period versus 6.27% (1,342/21,416) of UK-born individuals. Migrants had 22% higher odds of infection during the second wave (total effect; OR:1.22, 95%CI:1.01-1.47). Household overcrowding accounted for approximately 32% of these increased odds (indirect effect, OR:1.07, 95%CI:1.03-1.12; proportion accounted for: indirect effect[7]/total effect[22]=0.32). Conclusion: Migrants had higher odds of SARS-CoV-2 infection during the second wave compared with UK-born individuals and household overcrowding explained 32% of these increased odds. Policy interventions to reduce household overcrowding for migrants are needed as part of efforts to tackle health inequalities during the pandemic and beyond.
Subject(s)
COVID-19 , Severe Acute Respiratory SyndromeABSTRACT
Respiratory viruses that were suppressed through previous lockdowns during the COVID-19 pandemic have recently started to co-circulate with SARS-CoV-2. Understanding the clinical characteristics and symptomatology of different respiratory viral infections can help address the challenges related to the identification of cases and the understanding of SARS-CoV-2 variants' evolutionary patterns. Flu Watch (2006-2011) and Virus Watch (2020-2022) are household community cohort studies monitoring the epidemiology of influenza, respiratory syncytial virus, rhinovirus, seasonal coronavirus, and SARS-CoV-2, in England and Wales. This study describes and compares the proportion of symptoms reported during illnesses infected by common respiratory viruses. The SARS-CoV-2 symptom profile increasingly resembles that of other respiratory viruses as new strains emerge. Increased cough, sore throat, runny nose, and sneezing are associated with the emergence of the Omicron strains. As SARS-CoV-2 becomes endemic, monitoring the evolution of its symptomatology associated with new variants will be critical for clinical surveillance.
Subject(s)
COVID-19 , Respiratory Syncytial Virus InfectionsABSTRACT
ObjectivesTo assess whether workplace exposures as estimated via a COVID-19 Job Exposure Matrix (JEM) are associated with SARS-CoV-2. MethodsData on 244,470 participants were available from the ONS Coronavirus Infection Survey (CIS) and 16,801 participants from the Virus Watch Cohort, restricted to workers aged 20 to 64. Analysis used logistic regression models with SARS-CoV-2 as the dependent variable for eight individual JEM domains (number of workers, nature of contacts, contact via surfaces, indoor or outdoor location, ability to social distance, use of face covering, job insecurity, migrant workers) with adjustment for age, sex, ethnicity, Index of Multiple Deprivation (IMD), region, household size, urban vs rural area, and health conditions. Analyses were repeated for three time periods (i) February 2020 (Virus Watch)/April 2020 (CIS) to May 2021), (ii)June 2021 to November 2021, (iii) December 2021 to January 2022. ResultsOverall, higher risk classifications for the first six domains tended to be associated with an increased risk of infection, with little evidence of a relationship for domains relating to proportion of workers with job insecurity or migrant workers. By time there was a clear exposure-response relationship for these domains in the first period only. Results were largely consistent across the two cohorts. ConclusionsAn exposure-response relationship exists in the early phase of the COVID-19 pandemic for number of contacts, nature of contacts, contacts via surfaces, indoor or outdoor location, ability to social distance and use of face coverings. These associations appear to have diminished over time.
Subject(s)
COVID-19ABSTRACT
ABSTRACT Background Studies of COVID-19 vaccine effectiveness show increases in COVID-19 cases within 14 days of a first dose, potentially reflecting post-vaccination behaviour changes associated with SARS-CoV-2 transmission before vaccine protection. However, direct evidence for a relationship between vaccination and behaviour is lacking. We aimed to examine the association between vaccination status and self-reported non-household contacts and non-essential activities during a national lockdown in England and Wales. Methods Participants (n=1,154) who had received the first dose of a COVID-19 vaccine reported non-household contacts and non-essential activities from February to March 2021 in monthly surveys during a national lockdown in England and Wales. We used a case-crossover study design and conditional logistic regression to examine the association between vaccination status (pre-vaccination vs. 14 days post-vaccination) and self-reported contacts and activities within individuals. Stratified subgroup analyses examined potential effect heterogeneity by sociodemographic characteristics such as sex, household income or age group. Results 457/1,154 (39.60%) participants reported non-household contacts post-vaccination compared with 371/1,154 (32.15%) participants pre-vaccination. 100/1,154 (8.67%) participants reported use of non-essential shops or services post-vaccination compared with 74/1,154 (6.41%) participants pre-vaccination. Post-vaccination status was associated with increased odds of reporting non-household contacts (OR 1.65, 95% CI 1.31-2.06, p<0.001) and use of non-essential shops or services (OR 1.50, 95% CI 1.03-2.17, p=0.032). This effect varied between men and women and different age groups. Conclusion Participants had higher odds of reporting non-household contacts and use of non-essential shops or services within 14 days of their first COVID-19 vaccine compared to pre-vaccination. Public health emphasis on maintaining protective behaviours during this post-vaccination time period when individuals have yet to develop full protection from vaccination could reduce risk of SARS-CoV-2 infection.
Subject(s)
COVID-19ABSTRACT
Background: Occupational disparities in COVID-19 vaccine uptake can impact the effectiveness of vaccination programmes and introduce particular risk for vulnerable workers and those with high workplace exposure. This study aimed to investigate COVID-19 vaccine uptake by occupation, including for vulnerable groups and by occupational exposure status. Methods: We used data from employed or self-employed adults who provided occupational information as part of the Virus Watch prospective cohort study (n=19,595) and linked this to study-obtained information about vulnerability-relevant characteristics (age, medical conditions, obesity status) and work-related COVID-19 exposure based on the Job Exposure Matrix. Participant vaccination status for the first, second, and third dose of any COVID-19 vaccine was obtained based on linkage to national records and study records. We calculated proportions and Sison-Glaz multinomial 95% confidence intervals for vaccine uptake by occupation overall, by vulnerability-relevant characteristics, and by job exposure. Findings: Vaccination uptake across occupations ranged from 89-96% for the first dose, 87-94% for the second dose, and 75-86% for the third dose, with transport, trade, service and sales workers persistently demonstrating the lowest uptake. Vulnerable workers tended to demonstrate fewer between-occupational differences in uptake than non-vulnerable workers, although clinically vulnerable transport workers (76%-89% across doses) had lower uptake than several other occupational groups (maximum across doses 86-96%). Workers with low SARS-CoV-2 exposure risk had higher vaccine uptake (86%-96% across doses) than those with elevated or high risk (81-94% across doses). Interpretation: Differential vaccination uptake by occupation, particularly amongst vulnerable and highly-exposed workers, is likely to worsen occupational and related socioeconomic inequalities in infection outcomes. Further investigation into occupational and non-occupational factors influencing differential uptake is required to inform relevant interventions for future COVID-19 booster rollouts and similar vaccination programmes.
Subject(s)
COVID-19 , ObesityABSTRACT
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.
Subject(s)
COVID-19 , Eye InfectionsABSTRACT
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.
Subject(s)
Breakthrough PainABSTRACT
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.
Subject(s)
COVID-19 , InfectionsABSTRACT
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.
Subject(s)
COVID-19ABSTRACT
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.
Subject(s)
COVID-19 , Communicable DiseasesABSTRACT
Introduction: Infections of SARS-CoV-2 in vaccinated individuals have been increasing globally. Understanding the associations between vaccine type and a post-vaccination infection could help prevent further COVID-19 waves. In this paper, we use trial emulation to understand the impact of a phased introduction of the vaccine in the UK driven by vulnerability and exposure status. We estimate the comparative effectiveness of COVID-19 vaccines (ChAdOx1 versus BNT162b2) against post-vaccination infections of SARS-CoV-2 in a community setting in England and Wales. Method: Trial emulation was conducted by pooling results from six cohorts whose recruitment was staggered between 1st January 2021 and 31st March 2021 and followed until 12th November 2021. Eligibility for each trial was based upon age (18+ at the time of vaccination), without prior signs of infection or an infection within the first 14 days of the first dose. Time from vaccination of ChAdOx1 or BNT162b2 until SARS-CoV-2 infection (positive polymerase chain reaction or lateral flow test after 14 of the vaccination) was modelled using Cox proportional hazards model for each cohort and adjusted for age at vaccination, gender, minority ethnic status, clinically vulnerable status and index of multiple deprivation quintile. For those without SARS-CoV-2 infection during the study period, follow-up was until loss-of-follow-up or end of study (12th November 2021). Pooled hazard ratios were generated using random-effects meta-analysis. Results: Across six cohorts, there were a total of 21,283 participants who were eligible and vaccinated with either ChAdOx1 (n = 13,813) or BNT162b2 (n = 7,470) with a median follow-up time of 266 days (IQR: 235 - 282). By November 12th 2021, 750 (5.4%) adults who had ChAdOx1 as their vaccine experienced a SARS-CoV-2 infection, compared to 296 (4.0%) who had BNT162b2. We found that people who received ChAdOx1 vaccinations had 10.54 per 1000 people higher cumulative incidence for SARS-CoV-2 infection compared to BNT162b2 for infections during a maximum of 315 days of follow-up. When adjusted for age at vaccination, sex, minority ethnic status, index of multiple deprivation, and clinical vulnerability status, we found a pooled adjusted hazard ratio of 1.35 [HR: 1.35, 95%CI: 1.15 - 1.58], demonstrating a 35% increase in SARS-CoV-2 infections in people who received ChAdOx1 compared to BNT162b2. Discussion: We found evidence of greater effectiveness of receiving BNT162b2 compared to ChAdOx1 vaccines against SARS-CoV-2 infection in England and Wales during a time period when Delta became the most prevalent variant of concern. Our findings demonstrate the importance of booster (third) doses to maintain protection and suggest that these should be prioritised to those who received ChAdOx1 as their primary course.
Subject(s)
COVID-19 , Sleep Deprivation , Severe Acute Respiratory SyndromeABSTRACT
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.