Prevalence of SARS-CoV-2 in Household Members and Other Close Contacts of COVID-19 Cases: A Serologic Study in Canton of Vaud, Switzerland.
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ABSTRACT: Background
Research on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission within households and other close settings using serological testing is scarce.Methods
We invited coronavirus disease 2019 (COVID-19) cases diagnosed between February 27 and April 1, 2020, in Canton of Vaud, Switzerland, to participate, along with household members and other close contacts. Anti-SARS-CoV-2 immunoglobulin G antibodies were measured using a Luminex immunoassay. We estimated factors associated with serological status using generalized estimating equations.Results
Overall, 219 cases, 302 household members, and 69 other close contacts participated between May 4 and June 27, 2020. More than half of household members (57.2%; 95% CI, 49.7%-64.3%) had developed a serologic response to SARS-CoV-2, while 19.0% (95% CI, 10.0%-33.2%) of other close contacts were seropositive. After adjusting for individual and household characteristics, infection risk was higher in household members aged ≥65 years than in younger adults (adjusted odds ratio [aOR], 3.63; 95% CI, 1.05-12.60) and in those not strictly adhering to simple hygiene rules like hand washing (aOR, 1.80; 95% CI, 1.02-3.17). The risk was lower when more than 5 people outside home were met during semiconfinement, compared with none (aOR, 0.35; 95% CI, 0.16-0.74). Individual risk of household members to be seropositive was lower in large households (22% less per each additional person).Conclusions
During semiconfinement, household members of a COVID-19 case were at very high risk of getting infected, 3 times more than close contacts outside home. This highlights the need to provide clear messages on protective measures applicable at home. For elderly couples, who were especially at risk, providing external support for daily basic activities is essential.
SUBMITTER: Dupraz J
PROVIDER: S-EPMC8083624 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:IntroductionContinuity of care, especially for patients with complex needs, is a major challenge for healthcare systems in many high-income countries, including Switzerland. Since 2015, a collaborative project between Unisanté-Department of Family Medicine (DMF), some general practitioners (GPs) and canton of Vaud's public health authorities has sought to develop a new organisational model for the provision of primary care to ensure better care coordination and to provide adapted care deliveries to patients' healthcare needs. The model's main component is the addition of a primary care nurse to GPs practices. Three additional tools are individualised patient care plans, electronic medical records and patient empanelment. To assess this model, a 2-year pilot study has begun in nine GPs' practices in the canton. This paper presents the protocol for an evaluation of the implementation and effectiveness of the new organisational model.Method and analysisWe will conduct a before-and-after study using a mixed-methods and a realist approach. First, we will use quantitative and qualitative data to assess the new organisational model's implementation (feasibility, fidelity, acceptability and costs) and effectiveness (healthcare services use, patient experience, staff experience and patient-level costs). Combining this data with focus group data will enable a realist evaluation of the pilot project, which will help understand the elements of context and mechanism that affect implementation.Ethics and disseminationThe evaluation will inform the canton of Vaud's health authorities about the limits of and perspectives for this organisational model. All results will also be made available to the practices and the patients involved. At the end of the project, we will propose organisational adaptations and a sustainable financial model for extending the model to other practices in the canton and potentially to the national level.The canton of Vaud's Human Research Ethics Committee approved the study, and Data Protection and Information Law Authority gave a favourable opinion concerning data processing procedures.
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Project description:BackgroundCOVID-19 vaccination was expected to reduce SARS-CoV-2 transmission, but the relevance of this effect remains unclear. We aimed to estimate the effectiveness of COVID-19 vaccination of the index cases and their close contacts in reducing the probability of SARS-CoV-2 transmission.MethodsTransmission of SARS-CoV-2 infection was evaluated in two cohorts of adult close contacts of COVID-19 confirmed cases (social and household settings) by COVID-19 vaccination status of the index case and the close contact, from April to November 2021 in Navarre, Spain. The effects of vaccination of the index case and the close contact were estimated as (1-adjusted relative risk) × 100%.ResultsAmong 19,631 social contacts, 3257 (17%) were confirmed with SARS-CoV-2. COVID-19 vaccination of the index case reduced infectiousness by 44% (95% CI, 27-57%), vaccination of the close contact reduced susceptibility by 69% (95% CI, 65-73%), and vaccination of both reduced transmissibility by 74% (95% CI, 70-78%) in social settings, suggesting some synergy of effects. Among 20,708 household contacts, 6269 (30%) were infected, and vaccine effectiveness estimates were 13% (95% CI, -5% to 28%), 61% (95% CI, 58-64%), and 52% (95% CI, 47-56%), respectively. These estimates were lower in older people and had not relevant differences between the Alpha (April-June) and Delta (July-November) variant periods.ConclusionsCOVID-19 vaccination reduces infectiousness and susceptibility; however, these effects are insufficient for complete control of SARS-CoV-2 transmission, especially in older people and household setting. Relaxation of preventive behaviors after vaccination may counteract part of the vaccine effect on transmission.
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