Corpus overview


Overview

MeSH Disease

Human Phenotype

Fever (9)

Anosmia (6)

Cough (5)

Pneumonia (3)

Myalgia (3)


Transmission

Seroprevalence
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    Dynamic Change of COVID-19 Seroprevalence SERO among Asymptomatic TRANS Population in Tokyo during the Second Wave

    Authors: Sawako Hibino; Kazutaka Hayashida; Andrew C Ahn; Yasutaka Hayashida; Julia Bielicki; Tim Roloff; Roland Bingisser; Christian Nickel; Nina Khanna; Sarah Tschudin; Andreas Widmer; Katharina Rentsch; Hans Pargger; Martin Siegemund; Daiana Stolz; Michael Tamm; Stefano Bassetti; Michael Osthoff; Manuel Battegay; Adrian Egli; Hans H Hirsch; Christine Goffinet; Florian Kurth; Martin Witzenrath; Maria Theresa Völker; Sarah Dorothea Müller; Uwe Gerd Liebert; Naveed Ishaque; Lars Kaderali; Leif Erik Sander; Sven Laudi; Christian Drosten; Roland Eils; Christian Conrad; Ulf Landmesser; Irina Lehmann

    doi:10.1101/2020.09.21.20198796 Date: 2020-09-23 Source: medRxiv

    Importance: Fatality rates related to COVID-19 in Japan have been low compared to Western Countries and have decreased despite the absence of lockdown. Serological tests SERO monitored across the course of the second wave can provide insights into the population-level prevalence SERO and dynamic patterns of COVID-19 infection MESHD. Objective: To assess changes in COVID-19 seroprevalence SERO among asymptomatic TRANS employees working in Tokyo during the second wave. Design: We conducted an observational cohort study. Healthy volunteers working for a Japanese company in Tokyo were enrolled from disparate locations to determine seropositivity against COVID19 from May 26 to August 25, 2020. COVID-19 IgM and IgG antibodies SERO were determined by a rapid COVID19 IgM/IgG test kit using fingertip blood SERO. Across the company, tests were performed and acquired weekly. For each participant, serology tests were offered twice, separated by approximately a month, to provide self-reference of test results and to assess for seroconversion and seroreversion. Setting: Workplace setting within a large company. Participants: Healthy volunteers from 1877 employees of a large Japanese company were recruited to the study from 11 disparate locations across Tokyo. Participants having fever HP fever MESHD, cough HP cough MESHD, or shortness of breath MESHD at the time of testing were excluded. Main Outcome(s) and Measure(s): Seropositivity rate (SPR) was calculated by pooled data from each two-weeks window across the cohort. Either IgM or IgG positivity was defined as seropositive. Changes in immunological status against SARS-CoV-2 were determined by comparing results between two tests obtained from the same individual. Results: Six hundred fifteen healthy volunteers (mean + SD 40.8 + 10.0; range 19-69; 45.7 % female TRANS) received at least one test. Seroprevalence SERO increased from 5.8 % to 46.8 % over the course of the summer. The most dramatic increase in SPR occurred in late June and early July, paralleling the rise in daily confirmed cases TRANS within Tokyo, which peaked on August 4. Out of the 350 individuals (mean + SD 42.5 + 10.0; range 19-69; 46.0 % female TRANS) who completed both offered tests, 21.4 % of those individuals who tested seronegative became seropositive and seroreversion was found in 12.2 % of initially seropositive participants. 81.1% of IgM positive cases at first testing became IgM negative in approximately one month. Conclusions and Relevance: COVID-19 infection MESHD may have spread widely across the general population of Tokyo despite the very low fatality rate. Given the temporal correlation between the rise in seropositivity and the decrease in reported COVID-19 cases that occurred without a shut-down, herd immunity may be implicated. Sequential testing for serological SERO response against COVID-19 is useful for understanding the dynamics of COVID-19 infection at the population-level.

    COVID-19 herd immunity in the Brazilian Amazon

    Authors: Lewis F Buss; Carlos Augusto Prete Jr.; Claudia MM Abrahim; Alfredo Mendrone Jr.; Tassila Salomon; Cesar de Almeida-Neto; Rafael FO França; Maria C Belotti; Maria PSS Carvalho; Allyson G Costa; Myuki AE Crispim; Suzete C Ferreira; Nelson A Fraiji; Susie Gurzenda; Charles Whittaker; Leonardo T Kamaura; Pedro L Takecian; Márcio K Moikawa; Anna S Nishiya; Vanderson Rocha; Nanci A Salles; Andreza A de Souza Santos; Martirene A da Silva; Brian Custer; Manoel Barral-Netto; Moritz Kraemer; Rafael HM Pererira; Oliver G Pybus; Michael P Busch; Márcia C Castro; Christopher Dye; Vitor H Nascimento; Nuno R Faria; Ester C Sabino

    doi:10.1101/2020.09.16.20194787 Date: 2020-09-21 Source: medRxiv

    The herd immunity threshold is the proportion of a population that must be immune to an infectious disease MESHD, either by natural infection MESHD or vaccination such that, in the absence of additional preventative measures, new cases decline and the effective reproduction number TRANS falls HP below unity. This fundamental epidemiological parameter is still unknown for the recently-emerged COVID-19, and mathematical models have predicted very divergent results. Population studies using antibody testing SERO to infer total cumulative infections can provide empirical evidence of the level of population immunity in severely affected areas. Here we show that the transmission TRANS of SARS-CoV-2 in Manaus, located in the Brazilian Amazon, increased quickly during March and April and declined more slowly from May to September. In June, one month following the epidemic peak, 44% of the population was seropositive for SARS-CoV-2, equating to a cumulative incidence of 52%, after correcting for the false-negative rate of the antibody test SERO. The seroprevalence SERO fell HP in July and August due to antibody SERO waning. After correcting for this, we estimate a final epidemic size of 66%. Although non-pharmaceutical interventions, plus a change in population behavior, may have helped to limit SARS-CoV-2 transmission TRANS in Manaus, the unusually high infection rate suggests that herd immunity played a significant role in determining the size of the epidemic.

    Sero-surveillance (IgG) of SARS-CoV-2 among Asymptomatic TRANS General population of Paschim Medinipur District, West Bengal, India(Conducted during last week of July and 1st week of August 2020) - A Joint Venture of VRDL Lab (ICMR), Midnapore Medical College & Hospital & Department of Health and Family Welfare,Govt. of West Bengal, Paschim Medinipur

    Authors: Parthasarathi Satpati; Saumya Sankar Sarangi; Kripasindhu Gantait; Sayantani Endow; Nimai Chandra Mandal; Panchanan Kundu; Subhadip Bhunia; Soham Sarangi; Vladimir Volynkin; Hermann Zellner; Rengul Cetin-Atalay; Maria Martin; Volkan Atalay; Makoto Miyara; Guy Gorochov; Amelie Guihot; Christophe Combadiere; Duraipandian Thavaselvam; Devendra Kumar Dubey; Paul Lin; Hila Shaim; Sean G Yates; David Marin; Indreshpal Kaur; Sheetal Rao; Duncan Mak; Angelique Lin; Qi Miao; Jinzhuang Dou; Ken Chen; Richard Champlin; Elizabeth J Shpall; Katayoun Rezvani

    doi:10.1101/2020.09.12.20193219 Date: 2020-09-14 Source: medRxiv

    Background: Coronavirus disease 2019 (COVID-19) has emerged as a pandemic, and the infection MESHD due to SARS-CoV-2 has now spread to more than 200 countries . Surveillance systems form the foundation stone of active case finding, testing and contact tracing TRANS, which are the key components of the public health response to this novel, emerging infectious disease MESHD . There is uncertainty about the true proportion of patients who remain asymptomatic TRANS or pre-symptomatic at a given time. As per the WHO-China Joint Monitoring Mission Report, and an analysis of 21 published reports, anywhere between 5 and 80 per cent of SARS CoV 2 infected MESHD patients have been noted to be asymptomatic TRANS. Whereas in India 4197563 cases are positive, in which in West Bengal total 180788 cases (4.04% of Cases of India) positive of COVID 19. In Paschim Medinipur (West Medinipur) district contributing total 5489 cases (3.03% cases of West Bengal). In this scenario, we want to know the status of IgG seroprevalence SERO of SARS CoV 2 among asymptomatic TRANS general population, so that we can determine the extent of infection of SARS CoV MESHD 2 in general population. Objectives: Primary Objective: To estimate the seroprevalence SERO for SARS CoV 2 infection MESHD in the general asymptomatic TRANS population at Paschim Medinipur District. Secondary Objectives: To estimate age TRANS and sex specific seroprevalence SERO. To determine the socio demographic risk factors for SARS CoV 2 infection MESHD; To determine the other risk factors like comorbidities, vaccination status, travel TRANS history, contact history etc.; To determine the durability of Immunity (IgG) conferred by natural infection of SARS-CoV-2 MESHD in individuals previously RTPCR positive. Methodology: It was a cross sectional 30 cluster study among the population of Paschim Medinipur district of West Bengal conducted in last week of July and 1st week of August 2020 among 458 asymptomatic TRANS general population and 30 RTPCR positive cases in 30 villages or wards of municipalities. 30 clusters were chosen from list of COVID 19 affected villages/wards of municipality as per PPS (Probability Proportional to Size) method. Results: Of the 458 asymptomatic TRANS general population,19 asymptomatic TRANS people found to be seropositive IgG for SARS CoV 2 with Mean or average total seropositivity rate of 4.15%. 19 Out of 30 (63.33%) RTPCR positive patients found Seronegative. Median of Days between RTPCR test and sero SERO negativity found was 60 with minimum 28 days to maximum 101 days and Range of 73 days and a standard deviation of 19.46. Among risk factors, the risk of having IgG is more in persons having Travel TRANS history with odds ratio of 2.99- 95%CI (1.17-7.65) with p-value- 0.02. Hydroxychloroquine prophylaxis with Odds ratio of 8.49- 95% CI(1.59-45.19) with p value - 0.003. Occupation as migrant labour with Odds ratio of 5.08- 95% CI(1.96-13.18) with p value of 0.001. H/O Chicken pox with Odds ratio of 2.15- 95% CI(0.59-7.79) with p value of 0.017. Influenza vaccinated with Odds ratio of 8.07 with 95% CI (0.8-81.48) with a p value of 0.036. Conclusion: Of the 458 asymptomatic TRANS general population,19 asymptomatic TRANS people found to be seropositive IgG for SARS-CoV-2 with Mean or average total seropositivity rate of 4.15%. 19 Out of 30 (63.33%) RTPCR positive patients found Seronegative. Median of Days between RTPCR test and sero SERO negativity found was 60 with minimum 28 days to maximum 101 days and Range of 73 days and a standard deviation of 19.46. Those having Travel TRANS History and having occupation MESHD as Migrant Labourer have significantly higher probability of getting infected with SARS-CoV-2. No role has been found of Hydroxychloroquine Medicines as Chemoprophylactic. No durable immunity conferred by natural infection with SARS-CoV-2 mean time to become seronegative after positive RTPCR test 60 days. So there is a chance of reinfection after average 2 months.

    Development, clinical translation, and utility of a COVID-19 antibody test SERO with qualitative and quantitative readouts

    Authors: Robert H. Bortz III; Catalina Florez; Ethan Laudermilch; Ariel S Wirchnianski; Gorka Lasso; Ryan J Malonis; George I Georgiev; Olivia Vergnolle; Natalia G Herrera; Nicholas C Morano; Sean T Campbell; Erika P. Orner; Amanda Mengotto; M Eugenia Dieterle; Jens Maximilian Fels; Denise Haslwanter; Rohit Jangra; Alev Celikgil; Duncan Kimmel; James H Lee; Margarette Mariano; Antonio Nakouzi; Jose Quiroz; Johanna Rivera; Wendy A Szymczak; Karen Tong; Jason Barnhill; Mattias NE Forsell; Clas Ahlm; Daniel T. Stein; Liise-anne Pirofski; Doctor Y Goldstein; Scott J. Garforth; Steven C. Almo; Johanna P. Daily; Michael B. Prystowsky; James D. Faix; Amy S. Fox; Louis M. Weiss; Jonathan R. Lai; Kartik Chandran

    doi:10.1101/2020.09.10.20192187 Date: 2020-09-11 Source: medRxiv

    The COVID-19 global pandemic caused by severe acute respiratory syndrome coronavirus-2 MESHD (SARS-CoV-2) continues to place an immense burden on societies and healthcare systems. A key component of COVID-19 control efforts is serologic testing SERO to determine the community prevalence SERO of SARS-CoV-2 exposure and quantify individual immune responses to prior infection MESHD or vaccination. Here, we describe a laboratory-developed antibody test SERO that uses readily available research-grade reagents to detect SARS-CoV-2 exposure in patient blood SERO samples with high sensitivity SERO and specificity. We further show that this test affords the estimation of viral spike-specific IgG titers from a single sample measurement, thereby providing a simple and scalable method to measure the strength of an individual's immune response. The accuracy, adaptability, and cost-effectiveness of this test makes it an excellent option for clinical deployment in the ongoing COVID-19 pandemic.

    Retrospective study of COVID-19 seroprevalence SERO among tissue donors at the onset of the outbreak before implementation of strict lockdown measures in France

    Authors: Nicolas Germain; Stephanie Herwegh; Anne Sophie Hatzfeld; Laurence Bocket; Brigitte Prevost; Pierre Marie Danze; Philippe Marchetti; Rachael Dodd; Brooke Nickel; Kristen Pickles; Samuel Cornell; Thomas Dakin; Kirsten J McCaffery; Aboubacar Sidiki Magassouba; Arsen Arakelyan; Denise Haslwanter; Rohit Jangra; Alev Celikgil; Duncan Kimmel; James H Lee; Margarette Mariano; Antonio Nakouzi; Jose Quiroz; Johanna Rivera; Wendy A Szymczak; Karen Tong; Jason Barnhill; Mattias NE Forsell; Clas Ahlm; Daniel T. Stein; Liise-anne Pirofski; Doctor Y Goldstein; Scott J. Garforth; Steven C. Almo; Johanna P. Daily; Michael B. Prystowsky; James D. Faix; Amy S. Fox; Louis M. Weiss; Jonathan R. Lai; Kartik Chandran

    doi:10.1101/2020.09.11.20192518 Date: 2020-09-11 Source: medRxiv

    Background: The COVID-19 pandemic has altered organ and tissue donations as well as transplantation practices. SARS-CoV-2 serological tests SERO could help in the selection of donors. We assessed COVID-19 seroprevalence SERO in a population of tissue donors, at the onset of the outbreak in France, before systematic screening of donors for SARS-CoV-2 RNA. Methods: 235 tissue donors at the Lille Tissue bank between November 1, 2019 and March 16, 2020 were included. Archived serum SERO samples were tested for SARS-CoV-2 antibodies SERO using two FDA-approved kits. Results: Most donors were at higher risks for severe COVID-19 illness including age TRANS over 65 years (142/235) and/or presence of co-morbidities (141/235). According to the COVID-19 risk assessment of transmission TRANS, 183 out of 235 tissue donors presented with a low risk level and 52 donors with an intermediate risk level of donor derived infection MESHD. Four out of the 235 (1.7%) tested specimens were positive for anti- SARS-CoV-2 antibodies SERO: 2 donors with anti-N protein IgG and 2 other donors with anti-S protein total Ig. None of them had both type of antibodies SERO. Conclusion: Regarding the seroprevalence SERO among tissue donors, we concluded that the transmission TRANS probability to recipient via tissue products was very low at the beginning of the outbreak.

    Clinical Performance SERO Evaluation of a SARS-CoV-2 Rapid Antibody Test SERO for Determining Past Exposure to SARS-CoV-2

    Authors: Peter Findeisen; Hugo Stiegler; Eloisa Lopez-Calle; Tanja Schneider; Eva Urlaub; Johannes Hayer; Claudia Silke Zemmrich

    doi:10.1101/2020.09.01.20180687 Date: 2020-09-04 Source: medRxiv

    The true prevalence SERO and population seropositivity of SARS-CoV-2 infection MESHD remains unknown, due to the number of asymptomatic TRANS infections MESHD and limited access to high- performance SERO antibody tests SERO. To control the COVID-19 pandemic it is crucial to understand the true seroprevalence SERO, but not every region has access to extensive centralized PCR and serology testing. Currently available rapid antibody tests SERO lack the accuracy needed for recommendation by health authorities. To fill this gap, we analyzed and validated the clinical performance SERO of a new point-of-care SARS-CoV-2 Rapid Antibody SERO Assay, a chromatographic immunoassay SERO for qualitative detection of IgM/IgG antibodies SERO for use in near-patient settings. Analysis was performed using 42 Anti-SARS-Cov-2 positive (CoV+) and 92 Anti-SARS-Covid-2 negative (CoV-) leftover samples from before December 2019, using the Elecsys(R) Anti-SARS-CoV-2 as the reference assay. Analytical specificity was tested using leftover samples from individuals with symptoms of common cold collected before December 2019. The SARS-CoV-2 Rapid Antibody Test SERO was 100.0% (95% CI 91.59-100.00) sensitive and 96.74% (95% CI 90.77-99.32) specific with an assay failure rate of 0.00%. No cross-reactivity was observed against the common cold panel. Method comparison was additionally conducted by two external laboratories, using 100 CoV+/275 CoV- samples, also comparing whole blood SERO versus plasma SERO matrix. The comparison demonstrated for plasma SERO 96.00% positive/96.36% negative percent agreement with the Elecsys Anti-SARS-CoV-2 and overall 99.20% percent agreement between whole blood SERO and EDTA plasma SERO. The SARS-CoV-2 Rapid Antibody Test SERO demonstrated similar clinical performance SERO to the manufacturer's data and to a centralized automated immunoassay SERO, with no cross-reactivity to common cold panels.

    Analyzing inherent biases in SARS-CoV-2 PCR and serological epidemiologic metrics

    Authors: Monia Makhoul; Farah Abou-Hijleh; Shaheen Seedat; Ghina R Mumtaz; Hiam Chemaitelly; Houssein Ayoub; Laith J Abu-Raddad; Xiaojian Liu; Wei Gao; Renli Zhang; Qiru Su; Andrew Azman; Justin Lessler; Xuan Zou; Wenfeng Gong; Brenda Clemente; Jerel Vega; Scott Roberts; Jose A. Gonzalez; Marciano Sablad; Rodrigo Yelin; Wendy Taylor; Kiyoshi Tachikawa; Suezanne Parker; Priya Karmali; Jared Davis; Sean M Sullivan; Steve G. Hughes; Pad Chivukula; Eng Eong Ooi

    doi:10.1101/2020.08.30.20184705 Date: 2020-09-02 Source: medRxiv

    Abstract Background: Prospective observational data show that infected persons with the severe acute respiratory syndrome coronavirus 2 MESHD (SARS-CoV-2) remain polymerase chain reaction (PCR) positive for a prolonged duration, and that detectable antibodies SERO develop slowly with time. We aimed to analyze how these effects can bias key epidemiological metrics used to track and monitor SARS-CoV-2 epidemics. Methods: An age TRANS-structured mathematical model was constructed to simulate progression of SARS-CoV-2 epidemics in populations. PCR testing to diagnose infection MESHD and cross-sectional surveys to measure seroprevalence SERO were also simulated. Analyses were conducted on simulated outcomes assuming a natural epidemic time course and an epidemic in presence of interventions. Results: The prolonged PCR positivity biased the epidemiological measures. There was a lag of 10 days between the true epidemic peak and the actually-observed peak. Prior to epidemic peak, PCR positivity rate was 2-fold higher than that based only on current active infection MESHD, and half of those tested positive by PCR were in the prolonged PCR positivity stage after infection clearance. Post epidemic peak, PCR positivity rate poorly predicted true trend in active infection MESHD. Meanwhile, the prolonged PCR positivity did not appreciably bias estimation of the basic reproduction number TRANS R0 TRANS. The time delay in development of detectable antibodies SERO biased measured seroprevalence SERO. The actually-observed seroprevalence SERO substantially underestimated true prevalence SERO of ever infection MESHD, with the underestimation being most pronounced around epidemic peak. Conclusions: Caution is warranted in interpreting PCR and serological testing SERO data, and any drawn inferences need to factor the effects of the investigated biases for an accurate assessment of epidemic dynamics.

    Seroprevalence SERO and immunity of SARS-CoV-2 infection MESHD in children TRANS and adolescents in schools in Switzerland: design for a longitudinal, school-based prospective cohort study

    Authors: Agne Ulyte; Thomas Radtke; Irene Abela; Sarah H Haile; Julia Braun; Ruedi Jung; Christoph Berger; Alexandra Trkola; Jan Fehr; Milo A Puhan; Susi Kriemler; Anel Nurtay; Lucie Abeler-Dörner; David G Bonsall; Michael V McConnell; Shawn O'Banion; Christophe Fraser; Scott Roberts; Jose A. Gonzalez; Marciano Sablad; Rodrigo Yelin; Wendy Taylor; Kiyoshi Tachikawa; Suezanne Parker; Priya Karmali; Jared Davis; Sean M Sullivan; Steve G. Hughes; Pad Chivukula; Eng Eong Ooi

    doi:10.1101/2020.08.30.20184671 Date: 2020-09-02 Source: medRxiv

    Introduction Seroprevalence SERO and transmission TRANS routes of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection MESHD in children TRANS and adolescents, especially in school setting, are not clear. Resulting uncertainty is reflected in very different decisions on school closures and reopenings across countries. The aim of this longitudinal cohort study is to assess the extent and patterns of seroprevalence SERO of SARS-CoV-2 antibodies SERO in school-attending children TRANS repeatedly. It will examine risk factors for infection MESHD, relationship between seropositivity and symptoms, and temporal persistence of antibodies SERO. Additionally, it will include testing of school personnel and parents TRANS. Methods and analysis The study (Ciao Corona) will enroll a regionally representative, random sample of schools in the canton of Zurich, where 18% of the Swiss population live. Children TRANS aged TRANS 5 to 16 years, attending classes in primary and secondary schools are invited. Venous blood MESHD blood SERO and saliva samples are collected for SARS-CoV-2 serological testing SERO after the first wave of infections (June/July 2020), in fall HP (October/November 2020), and after winter (March/April 2021). Venous blood MESHD blood SERO is also collected for serological testing SERO of parents TRANS and school personnel. Bi-monthly questionnaires to children TRANS, parents TRANS and school personnel cover SARS-CoV-2 symptoms MESHD and tests, health, preventive behavior, lifestyle and quality of life information. Total seroprevalence SERO and cumulative incidence will be calculated. Hierarchical Bayesian logistic regression models will account for sensitivity SERO and specificity of the serological test SERO in the analyses and for the complex sampling structure, i.e., clustering within classes and schools. Ethics and dissemination The study was approved by the Ethics Committee of the Canton of Zurich, Switzerland (2020-01336). The results of this study will be published in peer-reviewed journals and will be made available to study participants and participating schools, the Federal Office of Public Health, and the Educational Department of the canton of Zurich. Trial registration number NCT04448717.

    Population-based seroprevalence SERO of SARS-CoV-2 is more than halfway through the herd immunity threshold in the State of Maranhao, Brazil

    Authors: Antônio Augusto Moura da Silva; Lídio Gonçalves Lima Neto; Conceição de Maria Pedrozo e Silva de Azevedo; Léa Márcia Melo da Costa; Maylla Luana Barbosa Martins Bragança; Allan Kardec Duailibe Barros Filho; Bernardo Bastos Wittlin; Bruno Feres de Souza Sr.; Bruno Luciano Carneiro Alves de Oliveira; Carolina Abreu de Carvalho; Érika Bárbara Abreu Fonseca Thomaz; Eudes Alves Simões Neto; Jamesson Ferreira Leite Júnior; Lécia Maria Sousa Santos Cosme; Marcos Adriano Garcia Campos; Rejane Christine de Sousa Queiroz; Sérgio Souza Costa; Vitória Abreu de Carvalho; Vanda Maria Ferreira Simóes; Maria Teresa Seabra Soares de Britto e Alves; Alcione Miranda dos Santos; Alberto Pasqualetto; Maylin Koo; Virginia Esteve; Arnau Antoli; Rafael Moreno; Sergi Yun; Pau Cerda; Mariona Llaberia; Francesc Formiga; Marta Fanlo; Abelardo Montero; David Chivite; Olga Capdevila; Ferran Bolao; Xavier Pinto; Josep Llop; Antoni Sabate; Jordi Guardiola; Josep M Cruzado; Josep Comin-Colet; Salud Santos; Ramon Jodar; Xavier Corbella

    doi:10.1101/2020.08.28.20180463 Date: 2020-09-01 Source: medRxiv

    Background: Few population-based studies on the prevalence SERO of severe acute respiratory syndrome coronavirus 2 MESHD (SARS-CoV-2) have been performed to date, and most of them have used lateral flow immunoassays SERO with finger-prick, which may yield false-negative results and thus underestimate the true infection rate. Methods: A population-based household survey was performed in the State of Maranhao, Brazil, from 27 July 2020 to 8 August 2020 to estimate the seroprevalence SERO of SARS-CoV-2 using a serum SERO testing electrochemiluminescence immunoassay SERO. A three-stage cluster sampling stratified by four state regions was used. The estimates took clustering, stratification, and non-response into account. Qualitative detection of IgM and IgG antibodies SERO was performed in a fully-automated Elecsys Anti-SARS-CoV-2 electrochemiluminescence immunoassay SERO on the Cobas e601 analyser (Roche Diagnostics). Findings: A total of 3156 individuals were interviewed. Seroprevalence SERO of total antibodies SERO against SARS-CoV-2 was 40.4% (95%CI 35.6-45.3). Population adherence to non-pharmaceutical interventions was higher at the beginning of the pandemic than in the last month. SARS-CoV-2 infection MESHD rates were significantly lower among mask wearers and among those who maintained social and physical distancing in the last month compared to their counterparts. Among the infected, 62.2% had more than three symptoms, 11.1% had one or two symptoms, and 26.0% were asymptomatic TRANS. The infection MESHD fatality rate was 0.17%, higher for males TRANS and advanced age groups TRANS. The ratio of estimated infections MESHD to reported cases was 22.2. Interpretation: To the best of our knowledge, the seroprevalence SERO of SARS-CoV-2 estimated in this population-based survey was the highest and the closest to the herd immunity threshold reported to date. Our results suggest that the herd immunity threshold is not as low as 20%, but at least higher than or equal to around 40%. The infection MESHD fatality rate was one of the lowest reported so far, and the proportion of asymptomatic TRANS cases was low.

    Analyzing inherent biases in SARS-CoV-2 PCR and serological epidemiologic metrics

    Authors: Monia Makhoul; Farah Abou-Hijleh; Shaheen Seedat; Ghina R Mumtaz; Hiam Chemaitelly; Houssein Ayoub; Laith J. Abu-Raddad

    doi:10.21203/rs.3.rs-70006/v1 Date: 2020-09-01 Source: ResearchSquare

    Background Prospective observational data show that infected persons with the severe acute respiratory syndrome coronavirus 2 MESHD (SARS-CoV-2) remain polymerase chain reaction (PCR) positive for a prolonged duration, and that detectable antibodies SERO develop slowly with time. We aimed to analyze how these effects can bias key epidemiological metrics used to track and monitor SARS-CoV-2 epidemics.Methods An age TRANS-structured mathematical model was constructed to simulate progression of SARS-CoV-2 epidemics in populations. PCR testing to diagnose infection MESHD and cross-sectional surveys to measure seroprevalence SERO were also simulated. Analyses were conducted on simulated outcomes assuming a natural epidemic time course and an epidemic in presence of interventions.Results The prolonged PCR positivity biased the epidemiological measures. There was a lag of 10 days between the true epidemic peak and the actually-observed peak. Prior to epidemic peak, PCR positivity rate was 2-fold higher than that based only on current active infection MESHD, and half of those tested positive by PCR were in the prolonged PCR positivity stage after infection clearance. Post epidemic peak, PCR positivity rate poorly predicted true trend in active infection MESHD. Meanwhile, the prolonged PCR positivity did not appreciably bias estimation of the basic reproduction number TRANS R0 TRANS. The time delay in development of detectable antibodies SERO biased measured seroprevalence SERO. The actually-observed seroprevalence SERO substantially underestimated true prevalence SERO of ever infection MESHD, with the underestimation being most pronounced around epidemic peak.Conclusions Caution is warranted in interpreting PCR and serological testing SERO data, and any drawn inferences need to factor the effects of the investigated biases for an accurate assessment of epidemic dynamics.

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MeSH Disease
Human Phenotype
Transmission
Seroprevalence


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