Interventions to control nosocomial transmission of SARS-CoV-2: a modelling study
TL;DR: In this article, the authors developed an agent-based model and compared the impact of personal protective equipment (PPE), screening of healthcare workers (HCWs), contact tracing of symptomatic HCWs, and restricting HCWs from working in multiple units (HCW cohorting) on nosocomial SARS-CoV-2 transmission.
Abstract: BackgroundEmergence of more transmissible SARS-CoV-2 variants requires more efficient control measures to limit nosocomial transmission and maintain healthcare capacities during pandemic waves. Yet, the relative importance of different strategies is unknown. MethodsWe developed an agent-based model and compared the impact of personal protective equipment (PPE), screening of healthcare workers (HCWs), contact tracing of symptomatic HCWs, and restricting HCWs from working in multiple units (HCW cohorting) on nosocomial SARS-CoV-2 transmission. The model was fit on hospital data from the first wave in the Netherlands (February until August 2020) and assumed that HCWs used 90% effective PPE in COVID-19 wards and self-isolated at home for seven days immediately upon symptom onset. Intervention effects on the effective reproduction number (RE), HCW absenteeism and the proportion of infected individuals among tested individuals (positivity rate) were estimated for a more transmissible variant. ResultsIntroduction of a variant with 56% higher transmissibility increased - all other variables kept constant - RE from 0.4 to 0.65 (+63%) and nosocomial transmissions by 303%, mainly because of more transmissions caused by pre-symptomatic patients and HCWs. Compared to baseline, PPE use in all hospital wards (assuming 90% effectiveness) reduced RE by 85% and absenteeism by 57%. Screening HCWs every three days with perfect test sensitivity reduced RE by 67%, yielding a maximum test positivity rate of 5%. Screening HCWs every three or seven days assuming time-varying test sensitivities reduced RE by 9% and 3%, respectively. Contact tracing reduced RE by at least 32% and achieved higher test positivity rates than screening interventions. HCW cohorting reduced RE by 5%. Sensitivity analyses for 50% and 70% effectiveness of PPE use did not change interpretation. ConclusionsIn response to the emergence of more transmissible SARS-CoV-2 variants, PPE use in all hospital wards might still be most effective in preventing nosocomial transmission. Regular screening and contact tracing of HCWs are also effective interventions, but critically depend on the sensitivity of the diagnostic test used.
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TL;DR: In this article, a rapid scoping review aims to provide a synthesis of current evidence related to public health measures and health system arrangements associated with VOCs, including lockdowns, physical distancing, testing and contact tracing.
Abstract: BackgroundAs of April 2021, three SARS-CoV-2 variants of concern (VOC: B.1.1.7, B.1.351 and P.1) have been detected in over 132 countries. Increased transmissibility of VOC has implications for public health measures and health system arrangements. This rapid scoping review aims to provide a synthesis of current evidence related to public health measures and health system arrangements associated with VOC. MethodsRapid scoping review. Seven databases were searched up to April 7, 2021 for terms related to VOC, transmission, public health and health systems. A grey literature search was conducted up to April 14, 2021. Title, abstracts and full text were screened independently by two reviewers. Data were double extracted using a standardized form. Studies were included if they reported on at least one of the VOC and public health or health system outcomes. ResultsOf the 2487 articles and 59 grey literature sources retrieved, 37 studies and 21 guidance documents were included. Included studies used a wide range of designs and methods. Most of the studies and guidance documents reported on B.1.1.7, and 18 studies and 4 reports provided data for consideration in relation to public health measures. Public health measures, including lockdowns, physical distancing, testing and contact tracing, were identified as critical adjuncts to a comprehensive vaccination campaign. No studies reported on handwashing or masking procedures related to VOC. For health system arrangements, 17 studies were identified. Some studies found an increase in hospitalization due to B.1.1.7 but no difference in length of stay or ICU admission. Six studies found an increased risk of death ranging from 15-67% with B.1.1.7 compared non-B.1.1.7, but three studies reported no change. One study reported on the effectiveness of personal protective equipment in reducing VOC transmission in the hospital. No studies reported on screening staff and visitors, adjusting service provisions, or adjusting patient accommodations and shared spaces, which is a significant gap in the literature. Guidance documents did not tend to cite any evidence and were thus assumed to be based on expert opinion. ConclusionWhile the findings should be interpreted with caution as most of the sources identified were preprints, findings suggest a combination of non-pharmaceutical interventions (e.g., masking, physical distancing, lockdowns, testing) should be employed alongside a vaccine strategy to improve population and health system outcomes. While the findings are mixed on the impact of VOC on health system arrangements, the evidence is trending towards increased hospitalization and death.
5 citations
TL;DR: In this paper, the authors evaluated the efficacy and health-economic efficiency of single or repeated population-wide Antigen Rapid Diagnostics (ARDT) screening interventions implemented in response to surges in nosocomial outbreak risk.
Abstract: Background Surges in community SARS-CoV-2 incidence increase risk of importation and subsequent transmission in healthcare facilities. Antigen rapid diagnostic testing (Ag-RDT) is widely used for population screening, but its health and economic benefits as a reactive intervention in healthcare settings are unclear. Methods We used stochastic, individual-based modelling to simulate SARS-CoV-2 transmission in a long-term care facility with varying COVID-19 containment measures in place (social distancing, face masks, vaccination). In contrast to routine symptomatic testing using reverse-transcriptase polymerase chain reaction (RT-PCR), we evaluated the efficacy and health-economic efficiency of single or repeated population-wide Ag-RDT screening interventions implemented in response to surges in nosocomial outbreak risk. Results Depending on the baseline containment measures in place, nosocomial SARS-CoV-2 incidence was reduced by up to 40-47% (range of means) with routine RT-PCR testing, 59-63% with the addition of a timely round of Ag-RDT screening, and 69-75% with well-timed two-round screening. For the latter, a delay of 4 to 5 days between the first and second rounds was optimal for transmission prevention. Efficacy varied depending on test sensitivity, subpopulations targeted, and SARS-CoV-2 incidence in the community. Efficiency, however, varied primarily depending on the other containment measures in place: surveillance costs for a combined strategy of routine RT-PCR testing and reactive Ag-RDT screening ranged from a mean €420-€10,260/infection averted across scenarios (default unit costs: €5/Ag-RDT test, €50/RT-PCR test). Interpretation Reactive Ag-RDT screening complements routine RT-PCR testing, and systematic two-round screening helps overcome limited, time-varying diagnostic sensitivity. Health-economic gains scale significantly with underlying nosocomial outbreak risk. Funding National Research Agency, Canadian Institutes of Health Research, Fondation de France
2 citations
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TL;DR: Hospitalised COVID-19 patients are frequently elderly subjects with co-morbidities receiving polypharmacy, all of which are known risk factors for d
Abstract: Background: Hospitalised COVID-19 patients are frequently elderly subjects with co-morbidities receiving polypharmacy, all of which are known risk factors for d
14,343 citations
TL;DR: The results support current proposals for the length of quarantine or active monitoring of persons potentially exposed to SARS-CoV-2, although longer monitoring periods might be justified in extreme cases.
Abstract: Using news reports and press releases from provinces, regions, and countries outside Wuhan, Hubei province, China, this analysis estimates the length of the incubation period of COVID-19 and its pu...
5,215 citations
TL;DR: Using a variety of statistical and dynamic modeling approaches, the authors estimate that this variant has a 43 to 90% (range of 95% credible intervals, 38 to 130%) higher reproduction number than preexisting variants, and a fitted two-strain dynamic transmission model shows that VOC 202012/01 will lead to large resurgences of COVID-19 cases.
Abstract: A severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant, VOC 202012/01 (lineage B.1.1.7), emerged in southeast England in September 2020 and is rapidly spreading toward fixation. Using a variety of statistical and dynamic modeling approaches, we estimate that this variant has a 43 to 90% (range of 95% credible intervals, 38 to 130%) higher reproduction number than preexisting variants. A fitted two-strain dynamic transmission model shows that VOC 202012/01 will lead to large resurgences of COVID-19 cases. Without stringent control measures, including limited closure of educational institutions and a greatly accelerated vaccine rollout, COVID-19 hospitalizations and deaths across England in the first 6 months of 2021 were projected to exceed those in 2020. VOC 202012/01 has spread globally and exhibits a similar transmission increase (59 to 74%) in Denmark, Switzerland, and the United States.
1,935 citations
TL;DR: In the UK and the USA, risk of reporting a positive test for COVID-19 was increased among front-line health-care workers, and adequacy of PPE, clinical setting, and ethnic background were also important factors.
Abstract: Summary Background Data for front-line health-care workers and risk of COVID-19 are limited. We sought to assess risk of COVID-19 among front-line health-care workers compared with the general community and the effect of personal protective equipment (PPE) on risk. Methods We did a prospective, observational cohort study in the UK and the USA of the general community, including front-line health-care workers, using self-reported data from the COVID Symptom Study smartphone application (app) from March 24 (UK) and March 29 (USA) to April 23, 2020. Participants were voluntary users of the app and at first use provided information on demographic factors (including age, sex, race or ethnic background, height and weight, and occupation) and medical history, and subsequently reported any COVID-19 symptoms. We used Cox proportional hazards modelling to estimate multivariate-adjusted hazard ratios (HRs) of our primary outcome, which was a positive COVID-19 test. The COVID Symptom Study app is registered with ClinicalTrials.gov, NCT04331509. Findings Among 2 035 395 community individuals and 99 795 front-line health-care workers, we recorded 5545 incident reports of a positive COVID-19 test over 34 435 272 person-days. Compared with the general community, front-line health-care workers were at increased risk for reporting a positive COVID-19 test (adjusted HR 11·61, 95% CI 10·93–12·33). To account for differences in testing frequency between front-line health-care workers and the general community and possible selection bias, an inverse probability-weighted model was used to adjust for the likelihood of receiving a COVID-19 test (adjusted HR 3·40, 95% CI 3·37–3·43). Secondary and post-hoc analyses suggested adequacy of PPE, clinical setting, and ethnic background were also important factors. Interpretation In the UK and the USA, risk of reporting a positive test for COVID-19 was increased among front-line health-care workers. Health-care systems should ensure adequate availability of PPE and develop additional strategies to protect health-care workers from COVID-19, particularly those from Black, Asian, and minority ethnic backgrounds. Additional follow-up of these observational findings is needed. Funding Zoe Global, Wellcome Trust, Engineering and Physical Sciences Research Council, National Institutes of Health Research, UK Research and Innovation, Alzheimer's Society, National Institutes of Health, National Institute for Occupational Safety and Health, and Massachusetts Consortium on Pathogen Readiness.
1,556 citations
TL;DR: Overall, the data indicate that, similar to SARS in 2002–03, Viral dynamics in mild and severe cases of COVID-19 are similar to that of SARS.
Abstract: www.thelancet.com/infection Published online March 19, 2020 https://doi.org/10.1016/S1473-3099(20)30232-2 1 day of disease onset at the time of sampling. The DCt values of severe cases remained significantly lower for the first 12 days after onset than those of corresponding mild cases (figure A). We also studied serial samples from 21 mild and ten severe cases (figure B). Mild cases were found to have an early viral clearance, with 90% of these patients repeatedly testing negative on RT-PCR by day 10 post-onset. By contrast, all severe cases still tested positive at or beyond day 10 postonset. Overall, our data indicate that, similar to SARS in 2002–03, Viral dynamics in mild and severe cases of COVID-19
1,447 citations