ABSTRACT
ObjectivesTo inform management of competing risks from Covid-19 and key-worker absence, we evaluated whether using two manufacturers lateral flow tests (LFTs) concurrently improved SARS-CoV-2 Omicron detection and was acceptable to hospital staff. In a nested study, to understand the risks of return to work after a fixed number of days of isolation or quarantine, we examined virus culture at Days 5-7 after positive test or significant exposure. Methods and Analysis1419 fully-vaccinated Liverpool (UK) University Hospitals staff participated in a random-order, open-label trial testing whether dual LFTs improved SARS-CoV2 detection, and whether dual swabbing was acceptable to users. Main outcome was self-reported LFT result. Staff enrolled via routine testing sites for symptomatic staff and close contacts. Recruitment took place between 7th February and 8th May 2022. Participants employed nose-throat swab Innova and nose-only swab Orient Gene LFTs for 10 days, with daily LFTs taken in random order. A swab for polymerase chain reaction (PCR) analysis was taken at Day-5 and, if positive, Day-10. A questionnaire on acceptability was administered on exit. Selected participants gave swabs for viral culture on Days 5-7; swabs were delivered and returned by courier. Cultures were considered positive if cytopathic effect was apparent or the SARs-COV2 N gene sub-genomic RNA was detected by sequencing. Results226 individuals reported 1466 pairs of LFT results. Tests disagreed in 127 cases (8.7%). Orient Gene was more likely (78 cf. 49, P=0.03) to be positive. Orient Gene positive Innova negative result-pairs became more frequent over time (P<0.001). If Innova was swabbed second, it was less likely to agree with a positive Orient Gene result (P=0.005); swabbing first with Innova made no significant difference (P=0.85). Of 311 individuals completing the exit questionnaire, 90.7% reported dual swabbing was easy, 57.1% said it was no barrier to their daily routine and 65.6% preferred dual testing. Respondents had more confidence in dual c.f. single test results (median 9 cf. 8 on 10-point scale, P<0.001). Viral cultures from swabs taken at Days 5-7 were positive for 6/31 (19.4%, 7.5%-37.5%) and indeterminate for 11/31 (35.5%, 19.2%-54.6%) LFT-positive participants, indicating they were likely still infectious. ConclusionsDual brand testing increased LFT detection of SARS-CoV-2 antigen by a small but meaningful margin and was acceptable to hospital workers. Viral cultures demonstrated that policies recommending safe return to work [~]5 days after Omicron infection/exposure were flawed. Key-workers should be prepared for dynamic self-testing protocols in future pandemics. Trial registrationhttps://www.isrctn.com/ISRCTN47058442 (IRAS Project ID:311842) Key messagesO_ST_ABSWhat is already known on this topicC_ST_ABSO_LIOmicron BA.1 and BA.2 waves caused large-scale healthcare worker absence in late 2021 - early 2022, risking patient safety from both Covid-19 and reduced care capacity C_LIO_LILateral flow tests (LFTs) reliably detected SARS-CoV-2 antigen, more so with Omicron than prior variants, identifying the most infectious individuals C_LIO_LISelf-testing with LFT SARS-CoV-2 rapid antigen tests reduced Covid-19 transmission, mitigating risks of return to work, including healthcare settings C_LI What this study addsO_LIDual c.f. single brand LFT testing increased SARS-CoV-2 antigen detection marginally, but more than can be explained by extending swabbing from nose-only to nose-throat C_LIO_LINHS deployment of nose-only LFTs in response to compound pressures from Omicron, winter and pandemic burnout was safe and acceptable to most participating hospital staff C_LIO_LICulturable virus was detected confidently in a fifth (and potentially in a further third) of LFT-positive hospital workers 5-7 days after their self-referral for testing, indicating substantial protracted infectiousness C_LI How this study might affect research, practice or policyO_LIThis study shows international Covid-19 policies for return to work after fixed periods (e.g. 5 days after positive test) were flawed: too little emphasis was placed on variation in infectivity between individuals C_LIO_LIFuture pandemic preparedness needs to plan testing quality assurance unified across healthcare and community self-testing contexts, including continuous study of serial daily antigen, nucleic acid and culturable virus test results C_LI
Subject(s)
COVID-19ABSTRACT
Objectives To assess the impact of Tier 3 covid-19 restrictions implemented in December 2020 in England on covid-19 hospital admissions compared to Tier 2 restrictions, and its potential variations by neighbourhood deprivation levels and the prevalence of the Alpha variant (B.1.1.7). Design Observational study utilising a synthetic control approach. Comparison of changes in weekly hospitalisation rates in Tier 3 areas to a synthetic control group derived from Tier 2 areas. Setting England between 4th October 2020 and 21st February 2021. Participants 23 million people under Tier 3 restrictions, compared to a synthetic control group derived from 29 million people under Tier 2 restrictions. Interventions Implementation of Tier 3 covid-19 restrictions in designated areas on 7th December 2020, with additional constraints on indoor and outdoor meetings and the hospitality sector compared to less stringent Tier 2 restrictions. Main Outcome Measures Weekly covid-19 related hospital admissions for neighbourhoods in England over a 12-week period following the interventions. Results The introduction of Tier 3 restrictions was associated with a 17% average reduction in hospital admissions compared to Tier 2 areas (95% CI 13% to 21%; 8158 (6286 to 9981) in total)). The effects were similar across different levels of neighbourhood deprivation and prevalence of the Alpha variant (B.1.1.7). Conclusions Regionally targeted Tier 3 restrictions in England had a moderate but significant effect on reducing hospitalisations. The impact did not exacerbate socioeconomic inequalities during the pandemic. Our findings suggest that regionally targeted restrictions can be effective in managing infectious diseases.
Subject(s)
COVID-19 , Sleep Deprivation , Communicable DiseasesABSTRACT
ObjectiveTo analyse the impact on hospital admissions for COVID-19 of large-scale, voluntary, public open access rapid testing for SARS-CoV-2 antigen in Liverpool (UK) between 6th November 2020 and 2nd January 2021. DesignSynthetic control analysis comparing hospital admissions for small areas in the intervention population to a group of control areas weighted to be similar in terms of prior COVID-19 hospital admission rates and socio-demographic factors. InterventionCOVID-SMART (Systematic Meaningful Asymptomatic Repeated Testing), a national pilot of large-scale, voluntary rapid antigen testing for people without symptoms of COVID-19 living or working in the City of Liverpool, deployed with the assistance of the British Army from the 6th November 2020 in an unvaccinated population. This pilot informed the UK roll-out of SARS-CoV-2 antigen rapid testing, and similar policies internationally. Main outcome measureWeekly COVID-19 hospital admissions for neighbourhoods in England. ResultsThe intensive introduction of COVID-SMART community testing was associated with a 43% (95% confidence interval: 29% to 57%) reduction in COVID-19 hospital admissions in Liverpool compared to control areas for the initial period of intensive testing with military assistance in national lockdown from 6th November to 3rd December 2020. A 25% (11% to 35%) reduction was estimated across the overall intervention period (6th November 2020 to 2nd January 2021), involving fewer testing centres, before Englands national roll-out of community testing, after adjusting for regional differences in Tiers of COVID-19 restrictions from 3rd December 2020 to 2nd January 2021. ConclusionsThe worlds first voluntary, city-wide SARS-CoV-2 rapid antigen testing pilot in Liverpool substantially reduced COVID-19 hospital admissions. Large scale asymptomatic rapid testing for SARS-CoV-2 can help reduce transmission and prevent hospital admissions. Summary boxO_ST_ABSWhat is already known on this topicC_ST_ABS- Previous studies on managing the spread of SARS-CoV-2 have identified asymptomatic transmission as significant challenges for controlling the pandemic. - Along with non-pharmaceutical measures, many countries rolled out population-based asymptomatic testing programmes to further limit transmission. - Evidence is required on whether large scale voluntary testing of communities for COVID-19 reduces severe disease, by breaking chains of transmission. What this study adds- The findings of this study suggest that large scale rapid antigen testing of communities for SARS-CoV-2, within an agile local public health campaign, can reduce transmission and prevent hospital admissions. - The results indicate that policy makers should integrate such testing into comprehensive, local public health programmes targeting high risk groups, supporting those required to isolate and adapting promptly to prevailing biological, behavioural and environmental circumstances.
Subject(s)
COVID-19ABSTRACT
Background From January to May 2021 the alpha variant (B.1.1.7) of SARS-CoV-2 was the most commonly detected variant in the UK, but since then the Delta variant (B.1.617.2), first detected in India, has become the predominant variant. The UK COVID-19 vaccination programme started on 8thDecember 2020. Most vaccine effectiveness studies to date have focused on the alpha variant. We therefore aimed to estimate the effectiveness of the BNT162b2 (Pfizer-BioNTech) and the ChAdOx1nCoV-19 (Oxford-AstraZeneca) vaccines in preventing infection with respect to the Delta variant in a UK setting. Methods We used anonymised public health record data linked to infection data (PCR) using the Combined Intelligence for Population Health Action resource. We then constructed an SIR epidemic model to explain SARS-CoV-2 infection data across the Cheshire and Merseyside region of the UK. Results We determined that the effectiveness of the Oxford-AstraZeneca vaccine in reducing susceptibility to infection is 39% (95% credible interval [34,43]) and 64% (95% credible interval [61,67]) for a single dose and a double dose respectively. For the Pfizer-BioNTech vaccine, the effectiveness is 20% (95% credible interval [10,28]) and 84% (95% credible interval [82,86]) for a single-dose and a double dose respectively. Conclusion Vaccine effectiveness for reducing susceptibility to SARS-CoV-2 infection shows noticeable improvement after receiving two doses of either vaccine. Findings also suggest that a full course of the Pfizer-BioNTech provides the optimal protection against infection with the Delta variant. This would advocate for completing the full course programme to maximise individual protection and reduce transmission.
Subject(s)
COVID-19ABSTRACT
Background: In 2020, a second wave of COVID-19 cases unevenly affected places in England leading to the introduction of a tiered system with different restrictions implemented geographically. Whilst previous research has examined the impact of national lockdowns on transmission, there has been limited research examining the marginal effect of differences in localised restrictions or how these effects vary by deprivation. Methods: We examined how Tier 3 restrictions affected COVID-19 case rates, and how these effects varied by level of deprivation, using data on weekly reported cases for 7201 neighbourhoods in England and adjusting these for changing case-detection rates. We identified areas that entered Tier 3 restrictions in October and December, constructed a synthetic control group of places under Tier 2 restrictions, and compared changes in weekly infections over a 4-week period. We used interaction analysis to estimate whether this effect varied by level of deprivation and the prevalence of a new variant (B.1.1.7). Results: The introduction of Tier 3 restrictions in October and December was associated with a 14% (95% CI 10% to 19%) and 20% (95% CI 13% to 29%) reduction in infections respectively, compared to the rates expected with Tier 2 restrictions only. The effects were similar across levels of deprivation and by the prevalence of the new variant. Interpretation: Compared to Tier 2 restrictions, additional restrictions on hospitality and meeting outdoors introduced in Tier 3 areas in England had a moderate effect on transmission and these restrictions did not appear to increase inequalities in COVID-19 cases.Funding Statement: BB, XZ are supported by the National Institute for Health Research(NIHR) Gastrointestinal Health Protection Research Unit. BB is also supported by the NIHR Applied Research Collaboration North West Coast (ARC NWC). GO is supported by the NIHR School for Public Health Research. IB is supported by NIHR Senior Investigator award. The viewsexpressed in this publication are those of the author(s) and not necessarily those of the NIHR or the Department of Health and Social.Declaration of Interests: None to declare.
Subject(s)
COVID-19ABSTRACT
Background In 2020, a second wave of COVID-19 cases unevenly affected places in England leading to the introduction of a tiered system of controls with different geographical areas subject to different levels of restrictions. Whilst previous research has examined the impact of national lockdowns on transmission, there has been limited research examining the marginal effect of differences in localised restrictions or how these effects vary between socioeconomic contexts. We therefore examined how Tier 3 restrictions in England implemented between October-December 2020, which included additional restrictions on the hospitality sector and people meeting outdoors affected COVID-19 case rates, compared to Tier 2 restrictions, and how these effects varied by level of deprivation. Methods We used data on weekly reported COVID-19 cases for 7201 neighbourhoods in England and adjusted these for changing case-detection rates to provide an estimate of weekly SARS-CoV-2 infections in each neighbourhood. We identified those areas that entered Tier 3 restrictions at two time points in October and December, and constructed a synthetic control group of similar places that had entered Tier 2 restrictions, using calibration weights to match them on a wide range of covariates that may influence transmission. We then compared the change in weekly infections between those entering Tier 3 to the synthetic control group to estimate the proportional reduction of cases resulting from Tier 3 restrictions compared to Tier 2 restrictions, over a 4-week period. We further used interaction analysis to estimate whether this effect differed based on the level of socioeconomic deprivation in each neighbourhood and whether effects were modified by the prevalence of a new more infectious variant of SARS-CoV-2 (B.1.1.7) in each area. Results The introduction of Tier 3 restrictions in October and December was associated with a 14% (95% CI 10% to 19%) and 20% (95% CI 13% to 29%) reduction in infections respectively, compared to the rates expected if only Tier 2 restrictions had been in place in those areas. We found that effects were similar across levels of deprivation and limited evidence that Tier 3 restrictions had a greater effect in areas where the new more infectious variant was more prevalent. Interpretation Additional restrictions on hospitality and meeting outdoors introduced in Tier 3 areas in England had a moderate effect on transmission and these restrictions did not appear to increase inequalities, having a similar impact across areas with differing levels of socioeconomic deprivation. Where transmission risks vary between geographical areas a tiered approach of local restrictions on outdoor mixing and hospitality can contribute to control of SARS-CoV-2 and is unlikely to increases inequalities in transmission.