Your browser doesn't support javascript.
Show: 20 | 50 | 100
Results 1 - 20 de 826
Filter
Add filters

Document Type
Year range
1.
PLoS One ; 16(12): e0260453, 2021.
Article in English | MEDLINE | ID: covidwho-1623646

ABSTRACT

A majority of SARS-CoV-2 infections are transmitted from a minority of infected subjects, some of which may be symptomatic or pre-symptomatic. We aimed to quantify potential infectiousness among asymptomatic healthcare workers (HCWs) in relation to prior or later symptomatic disease. We previously (at the onset of the SARS-CoV-2 epidemic) performed a cohort study of SARS-CoV-2 infections among 27,000 healthcare workers (HCWs) at work in the capital region of Sweden. We performed both SARS-CoV-2 RT-PCR and serology. Furthermore, the cohort was comprehensively followed for sick leave, both before and after sampling. In the present report, we used the cohort database to quantify potential infectiousness among HCWs at work. Those who had sick leave either before or after sampling were classified as post-symptomatic or pre-symptomatic, whereas the virus-positive subjects with no sick leave were considered asymptomatic. About 0.2% (19/9449) of HCW at work were potentially infectious and pre-symptomatic (later had disease) and 0.17% (16/9449) were potentially infectious and asymptomatic (never had sick leave either before nor after sampling). Thus, 33% and 28% of all the 57 potentially infectious subjects were pre-symptomatic or asymptomatic, respectively. When a questionnaire was administered to HCWs with past infection, only 10,5% of HCWs had had no indication at all of having had SARS-CoV-2 infection ("truly asymptomatic"). Our findings provide a unique quantification of the different groups of asymptomatic, potentially infectious HCWs.


Subject(s)
Asymptomatic Infections/epidemiology , COVID-19/epidemiology , Health Personnel/statistics & numerical data , Sick Leave/statistics & numerical data , Adult , Cohort Studies , Female , Humans , Male , Middle Aged , Sweden/epidemiology
2.
J Transl Med ; 19(1): 524, 2021 12 30.
Article in English | MEDLINE | ID: covidwho-1623635

ABSTRACT

BACKGROUND: Pronounced sex differences in the susceptibility and response to SARS-CoV-2 infection remain poorly understood. Emerging evidence has highlighted the potential importance of autoimmune activation in modulating the acute response and recovery trajectories following SARS-CoV-2 exposure. Given that immune-inflammatory activity can be sex-biased in the setting of severe COVID-19 illness, the aim of the study was to examine sex-specific autoimmune reactivity to SARS-CoV-2 in the absence of extreme clinical disease. METHODS: In this study, we assessed autoantibody (AAB) reactivity to 91 autoantigens previously linked to a range of classic autoimmune diseases in a cohort of 177 participants (65% women, 35% men, mean age of 35) with confirmed evidence of prior SARS-CoV-2 infection based on presence of antibody to the nucleocapsid protein of SARS-CoV-2. Data were compared to 53 pre-pandemic healthy controls (49% women, 51% men). For each participant, socio-demographic data, serological analyses, SARS-CoV-2 infection status and COVID-19 related symptoms were collected by  an electronic survey of questions. The symptoms burden score was constructed based on the total number of reported symptoms (N = 21) experienced within 6 months prior to the blood draw, wherein a greater number of symptoms corresponded to a higher score and assigned as more severe burden. RESULTS: In multivariable analyses, we observed sex-specific patterns of autoreactivity associated with the presence or absence (as well as timing and clustering of symptoms) associated with prior COVID-19 illness. Whereas the overall AAB response was more prominent in women following asymptomatic infection, the breadth and extent of AAB reactivity was more prominent in men following at least mildly symptomatic infection. Notably, the observed reactivity included distinct antigens with molecular homology with SARS-CoV-2. CONCLUSION: Our results reveal that prior SARS-CoV-2 infection, even in the absence of severe clinical disease, can lead to a broad AAB response that exhibits sex-specific patterns of prevalence and antigen selectivity. Further understanding of the nature of triggered AAB activation among men and women exposed to SARS-CoV-2 will be essential for developing effective interventions against immune-mediated sequelae of COVID-19.


Subject(s)
COVID-19 , Adult , Asymptomatic Infections , Cohort Studies , Female , Humans , Male , Pandemics , SARS-CoV-2
3.
Proc Natl Acad Sci U S A ; 119(2)2022 01 11.
Article in English | MEDLINE | ID: covidwho-1593390

ABSTRACT

We consider epidemiological modeling for the design of COVID-19 interventions in university populations, which have seen significant outbreaks during the pandemic. A central challenge is sensitivity of predictions to input parameters coupled with uncertainty about these parameters. Nearly 2 y into the pandemic, parameter uncertainty remains because of changes in vaccination efficacy, viral variants, and mask mandates, and because universities' unique characteristics hinder translation from the general population: a high fraction of young people, who have higher rates of asymptomatic infection and social contact, as well as an enhanced ability to implement behavioral and testing interventions. We describe an epidemiological model that formed the basis for Cornell University's decision to reopen for in-person instruction in fall 2020 and supported the design of an asymptomatic screening program instituted concurrently to prevent viral spread. We demonstrate how the structure of these decisions allowed risk to be minimized despite parameter uncertainty leading to an inability to make accurate point estimates and how this generalizes to other university settings. We find that once-per-week asymptomatic screening of vaccinated undergraduate students provides substantial value against the Delta variant, even if all students are vaccinated, and that more targeted testing of the most social vaccinated students provides further value.


Subject(s)
COVID-19/epidemiology , Return to School/methods , Asymptomatic Infections/epidemiology , COVID-19/diagnosis , COVID-19/prevention & control , COVID-19/transmission , Decision Making , Humans , Mass Screening , SARS-CoV-2/isolation & purification , Uncertainty , United States/epidemiology , Universities , Vaccination
5.
PLoS One ; 16(3): e0242777, 2021.
Article in English | MEDLINE | ID: covidwho-1574841

ABSTRACT

The Covid-19 pandemic has spread across the world since the beginning of 2020. Many regions have experienced its effects. The state of South Carolina in the USA has seen cases since early March 2020 and a primary peak in early April 2020. A lockdown was imposed on April 6th but lifting of restrictions started on April 24th. The daily case and death data as reported by NCHS (deaths) via the New York Times GitHUB repository have been analyzed and approaches to modeling of the data are presented. Prediction is also considered and the role of asymptomatic transmission is assessed as a latent unobserved effect. Two different time periods are examined and one step prediction is provided. The results suggest that both socio-economic disadvantage, asymptomatic transmission and spatial confounding are important ingredients in any model pertaining to county level case dynamics.


Subject(s)
COVID-19/epidemiology , Asymptomatic Infections/epidemiology , Bayes Theorem , Humans , Pandemics/prevention & control , Physical Distancing , Quarantine/methods , SARS-CoV-2/pathogenicity , South Carolina/epidemiology
6.
JAMA Netw Open ; 4(12): e2137257, 2021 12 01.
Article in English | MEDLINE | ID: covidwho-1567893

ABSTRACT

Importance: Asymptomatic infections are potential sources of transmission for COVID-19. Objective: To evaluate the percentage of asymptomatic infections among individuals undergoing testing (tested population) and those with confirmed COVID-19 (confirmed population). Data Sources: PubMed, EMBASE, and ScienceDirect were searched on February 4, 2021. Study Selection: Cross-sectional studies, cohort studies, case series studies, and case series on transmission reporting the number of asymptomatic infections among the tested and confirmed COVID-19 populations that were published in Chinese or English were included. Data Extraction and Synthesis: This meta-analysis was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline. Random-effects models were used to estimate the pooled percentage and its 95% CI. Three researchers performed the data extraction independently. Main Outcomes and Measures: The percentage of asymptomatic infections among the tested and confirmed populations. Results: Ninety-five unique eligible studies were included, covering 29 776 306 individuals undergoing testing. The pooled percentage of asymptomatic infections among the tested population was 0.25% (95% CI, 0.23%-0.27%), which was higher in nursing home residents or staff (4.52% [95% CI, 4.15%-4.89%]), air or cruise travelers (2.02% [95% CI, 1.66%-2.38%]), and pregnant women (2.34% [95% CI, 1.89%-2.78%]). The pooled percentage of asymptomatic infections among the confirmed population was 40.50% (95% CI, 33.50%-47.50%), which was higher in pregnant women (54.11% [95% CI, 39.16%-69.05%]), air or cruise travelers (52.91% [95% CI, 36.08%-69.73%]), and nursing home residents or staff (47.53% [95% CI, 36.36%-58.70%]). Conclusions and Relevance: In this meta-analysis of the percentage of asymptomatic SARS-CoV-2 infections among populations tested for and with confirmed COVID-19, the pooled percentage of asymptomatic infections was 0.25% among the tested population and 40.50% among the confirmed population. The high percentage of asymptomatic infections highlights the potential transmission risk of asymptomatic infections in communities.


Subject(s)
Asymptomatic Infections/epidemiology , COVID-19/epidemiology , SARS-CoV-2 , Adolescent , Adult , Aged , COVID-19/transmission , COVID-19/virology , COVID-19 Testing , Child , Female , Global Health , Humans , Male , Middle Aged , Pregnancy , Prevalence
7.
J Med Virol ; 94(1): 240-245, 2022 01.
Article in English | MEDLINE | ID: covidwho-1544340

ABSTRACT

Many countries in the world are experiencing a recent surge in COVID-19 cases. This is mainly attributed to the emergence of new SARS-CoV-2 variants. Genome sequencing is the only means to detect the evolving virus mutants and emerging variants. Cycle threshold values have an inverse relationship with viral load and lower Ct values are also found to be associated with increased infectivity. In this study, we propose to use Ct values as an early indicator for upcoming COVID-19 waves. A retrospective cross-sectional study was carried out to analyze the Ct values of positive samples reported during the first wave and second wave (April 2020-May 2021). Median Ct values of confirmatory genes were taken into consideration for comparison. Ct values below 25, >25-30, and >30 were categorized as high, moderate, and low viral load respectively. Our study found a significantly higher proportion of positive samples with a low Ct value (<25) across age groups and gender during the second wave of the COVID-19 pandemic. A higher proportion of positive samples with a low Ct value (high viral load) may act as an early indicator of an upcoming surge.


Subject(s)
COVID-19 Nucleic Acid Testing , COVID-19/diagnosis , COVID-19/epidemiology , Adolescent , Adult , Asymptomatic Infections/epidemiology , COVID-19/virology , Child , Child, Preschool , Cross-Sectional Studies , Female , Humans , Infant , Male , Middle Aged , Retrospective Studies , SARS-CoV-2/physiology , Viral Load , Young Adult
12.
Minerva Pediatr (Torino) ; 73(5): 460-466, 2021 Oct.
Article in English | MEDLINE | ID: covidwho-1513377

ABSTRACT

Inevitably, along with other healthcare specializations, pediatric surgery was affected by the Coronavirus disease-19 (COVID-19) pandemic. Children were reported to manifest mild to moderate symptoms and mortality was primarily observed in patients aged <1 year and having underlying comorbidities. Most of the cases were asymptomatic in children, hence, posing a challenge for pediatric surgery centers to take drastic measures to reduce the virus transmission. Telemedicine was introduced and out-patient consultations were conducted online as out-patient clinics were closed. Elective surgeries were postponed with delayed appointments while the healthcare sector was diverted towards tackling COVID-19. Case urgency was classified and triaged, leading to limited surgeries being performed only in COVID-19 negative patients following an extensive screening process. The screening process consisted of online history taking and RT-PCR tests. Newer practices such as mouth rinse, video laryngoscopy, and anesthesia were introduced to restrict patients from crying, coughing, and sneezing, as an attempt to avoid aerosolization of viral particles and safely conduct pediatric surgeries during the pandemic. Surgical trainees were also affected as the smaller number of surgeries conducted reduced the clinical experience available to medical enthusiasts. There is still room for advanced practices to be introduced in pediatric surgery and restore all kinds of surgeries to improve the quality of life of the patient.


Subject(s)
COVID-19/epidemiology , COVID-19/prevention & control , Pandemics , Pediatrics , Surgical Procedures, Operative , Asymptomatic Infections/epidemiology , COVID-19/diagnosis , COVID-19 Nucleic Acid Testing/methods , Child , Child, Preschool , Elective Surgical Procedures , General Surgery/education , Humans , Incidence , Infant , Patient Selection , Pediatrics/education , Preoperative Care/methods , Surgical Procedures, Operative/education , Telemedicine/organization & administration , Triage
13.
PLoS One ; 16(11): e0258700, 2021.
Article in English | MEDLINE | ID: covidwho-1504697

ABSTRACT

Protecting healthcare professionals is crucial in maintaining a functioning healthcare system. The risk of infection and optimal preventive strategies for healthcare workers during the COVID-19 pandemic remain poorly understood. Here we report the results of a cohort study that included pre- and asymptomatic healthcare workers. A weekly testing regime has been performed in this cohort since the beginning of the COVID-19 pandemic to identify infected healthcare workers. Based on these observations we have developed a mathematical model of SARS-CoV-2 transmission that integrates the sources of infection from inside and outside the hospital. The data were used to study how regular testing and a desynchronisation protocol are effective in preventing transmission of COVID-19 infection at work, and compared both strategies in terms of workforce availability and cost-effectiveness. We showed that case incidence among healthcare workers is higher than would be explained solely by community infection. Furthermore, while testing and desynchronisation protocols are both effective in preventing nosocomial transmission, regular testing maintains work productivity with implementation costs.


Subject(s)
Asymptomatic Infections , COVID-19 Testing/methods , COVID-19/diagnosis , COVID-19/economics , Health Personnel , SARS-CoV-2 , Algorithms , Cost-Benefit Analysis , Cross Infection , Data Collection , Delivery of Health Care , Hospitals , Humans , Mass Screening/methods , Models, Theoretical , Occupational Exposure , Pandemics , Risk , Stochastic Processes , Switzerland/epidemiology
16.
Microbiol Spectr ; 9(2): e0079321, 2021 10 31.
Article in English | MEDLINE | ID: covidwho-1495010

ABSTRACT

To determine the relationship between viral kinetics and severity of disease in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, we investigated the viral kinetics and compared the viral loads of patients with coronavirus disease 2019 (COVID-19; the disease caused by SARS-CoV-2), stratified by symptoms and severity. We determined the viral kinetics of 100 patients diagnosed with COVID-19 at Chosun University Hospital between February 2020 and May 2021 and analyzed the differences between asymptomatic, symptomatic, and nonsurvivor patients and between patients who died and those who survived. Clinical samples, comprising respiratory specimens (sputum samples and nasopharynx and oropharynx swab samples), were obtained at different time points of hospitalization, at 1, 3 to 5, 7, 10, 14, and 30 days. SARS-CoV-2 was detected using real-time reverse transcription-PCR (RT-PCR). All three groups, asymptomatic, symptomatic, and deceased patients, had higher numbers of viral copies at symptom onset, and the asymptomatic group had lower numbers of viral copies than the symptomatic or nonsurvivor group. Viral RNA release was detected until 30 days after symptom onset. The virus cleared up earlier in asymptomatic patients than in symptomatic and nonsurvivor patients, and it cleared up earlier in mildly affected patients than in severely affected patients. The cycle threshold values tended to be significantly lower in the group receiving steroids than in the nonsteroid group, even in the low-risk group with a pneumonia severity index of less than 90. The viral loads in patients with COVID-19 were significantly different according to disease severity and steroid use. IMPORTANCE In our study, we analyzed the viral kinetics of COVID-19 patients. Our study reveals differences in viral shedding according to the severity of disease in COVID-19 patients. Viral shedding had a longer duration in severely affected patients, and the cyclic threshold values were lower in the group receiving steroids. This study is expected to be helpful in analyzing the trend of the disease course according to steroid use and severity of SARS-CoV-2 disease.


Subject(s)
COVID-19/pathology , Severity of Illness Index , Viral Load , Virus Shedding , Aged , Aged, 80 and over , Asymptomatic Infections , COVID-19/mortality , Female , Humans , Male , Middle Aged , RNA, Viral/analysis , SARS-CoV-2/isolation & purification
17.
Viruses ; 12(8)2020 08 18.
Article in English | MEDLINE | ID: covidwho-1453290

ABSTRACT

Enteric viral co-infections, infections involving more than one virus, have been reported for a diverse group of etiological agents, including rotavirus, norovirus, astrovirus, adenovirus, and enteroviruses. These pathogens are causative agents for acute gastroenteritis and diarrheal disease in immunocompetent and immunocompromised individuals of all ages globally. Despite virus-virus co-infection events in the intestine being increasingly detected, little is known about their impact on disease outcomes or human health. Here, we review what is currently known about the clinical prevalence of virus-virus co-infections and how co-infections may influence vaccine responses. While experimental investigations into enteric virus co-infections have been limited, we highlight in vivo and in vitro models with exciting potential to investigate viral co-infections. Many features of virus-virus co-infection mechanisms in the intestine remain unclear, and further research will be critical.


Subject(s)
Coinfection/virology , Gastroenteritis/virology , Virus Diseases/physiopathology , Viruses/classification , Viruses/pathogenicity , Animals , Asymptomatic Infections , Disease Models, Animal , Feces/virology , Humans , Intestines/virology , Mice , Primates
18.
J Infect Dis ; 224(8): 1316-1324, 2021 10 28.
Article in English | MEDLINE | ID: covidwho-1493825

ABSTRACT

BACKGROUND: The coronavirus disease 2019 pandemic spread to >200 countries in <6 months. To understand coronavirus spread, determining transmission rate and defining factors that increase transmission risk are essential. Most cases are asymptomatic, but people with asymptomatic infection have viral loads indistinguishable from those in symptomatic people, and they do transmit severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, asymptomatic cases are often undetected. METHODS: Given high residence hall student density, the University of Colorado Boulder established a mandatory weekly screening test program. We analyzed longitudinal data from 6408 students and identified 116 likely transmission events in which a second roommate tested positive within 14 days of the index roommate. RESULTS: Although the infection rate was lower in single-occupancy rooms (10%) than in multiple-occupancy rooms (19%), interroommate transmission occurred only about 20% of the time. Cases were usually asymptomatic at the time of detection. Notably, individuals who likely transmitted had an average viral load approximately 6.5-fold higher than individuals who did not (mean quantification cycle [Cq], 26.2 vs 28.9). Although students with diagnosed SARS-CoV-2 infection moved to isolation rooms, there was no difference in time to isolation between cases with or without interroommate transmission. CONCLUSIONS: This analysis argues that interroommate transmission occurs infrequently in residence halls and provides strong correlative evidence that viral load is proportional to transmission probability.


Subject(s)
Asymptomatic Infections/epidemiology , COVID-19/transmission , SARS-CoV-2/pathogenicity , Viral Load , COVID-19/diagnosis , COVID-19/epidemiology , COVID-19/virology , Humans , Pandemics/prevention & control , Pandemics/statistics & numerical data , SARS-CoV-2/isolation & purification , Students , Young Adult
19.
Cell Res ; 31(11): 1148-1162, 2021 11.
Article in English | MEDLINE | ID: covidwho-1493088

ABSTRACT

Increasing numbers of SARS-CoV-2-positive (SARS-CoV-2pos) subjects are detected at silent SARS-CoV-2 infection stage (SSIS). Yet, SSIS represents a poorly examined time-window wherein unknown immunity patterns may contribute to the fate determination towards persistently asymptomatic or overt disease. Here, we retrieved blood samples from 19 asymptomatic and 12 presymptomatic SARS-CoV-2pos subjects, 47 age/gender-matched patients with mild or moderate COVID-19 and 27 normal subjects, and interrogated them with combined assays of 44-plex CyTOF, RNA-seq and Olink. Notably, both asymptomatic and presymptomatic subjects exhibited numerous readily detectable immunological alterations, while certain parameters including more severely decreased frequencies of CD107alow classical monocytes, intermediate monocytes, non-classical monocytes and CD62Lhi CD8+ Tnaïve cells, reduced plasma STC1 level but an increased frequency of CD4+ NKT cells combined to distinguish the latter. Intercorrelation analyses revealed a particular presymptomatic immunotype mainly manifesting as monocytic overactivation and differentiation blockage, a likely lymphocyte exhaustion and immunosuppression, yielding mechanistic insights into SSIS fate determination, which could potentially improve SARS-CoV-2 management.


Subject(s)
Asymptomatic Infections , COVID-19/immunology , Carrier State/immunology , Adult , B-Lymphocytes/immunology , COVID-19/pathology , Female , Humans , Leukocytes, Mononuclear/immunology , Male , Natural Killer T-Cells/immunology , SARS-CoV-2/physiology , T-Lymphocytes/immunology
20.
Biomedica ; 41(Sp. 2): 48-61, 2021 10 15.
Article in English, Spanish | MEDLINE | ID: covidwho-1478423

ABSTRACT

INTRODUCTION: The studies on knowledge, attitudes, and practices (KAP) regarding COVID-19 help to identify erroneous concepts and inadequate practices related to the disease. This baseline information is essential to design effective strategies and improve adherence to prevention measures. OBJECTIVE: To identify the COVID-19-related KAP in Venezuelan patients screened at the Hospital Universitario de Caracas triage tent. MATERIALS AND METHODS: We conducted a cross-sectional study among 215 patients between April 25th and May 25th, 2020, with in-person interviews using a KAP survey. RESULTS: Most surveyed patients (53.5%) were asymptomatic. Most of them, both from the symptomatic and the asymptomatic groups, had adequate knowledge about the symptoms and transmission of the disease and the majority said they were practicing quarantine, frequent handwashing, and the use of face masks in public areas. However, the daily replacement of cloth face masks was more frequent in the asymptomatic group whereas replacement every three days was more frequent in the symptomatic group. Finally, more than half of the participants admitted having been in crowded places, a common practice among the symptomatic compared to the asymptomatic patients. CONCLUSIONS: This is the first KAP study in Venezuela about COVID-19. Knowledge and practices among Venezuelans could be improved by strengthening education and training programs. This information from the early phase of the pandemic in Venezuela may contribute to the design of COVID-19 promotion and prevention strategies.


Introducción: Los estudios sobre conocimientos, actitudes y prácticas (CAP) sobre COVID-19 ayudan a identificar conceptos erróneos y prácticas inadecuadas relacionadas con la enfermedad. Esta información de referencia es fundamental para diseñar estrategias efectivas y mejorar la adherencia a las medidas de prevención. Objetivo: Identificar la CAP relacionada con COVID-19 en pacientes venezolanos cribados en la carpa de triaje del Hospital Universitario de Caracas. Materiales y métodos: Realizamos un estudio transversal entre 215 pacientes entre el 25 de abril y el 25 de mayo de 2020, con entrevistas en persona utilizando una encuesta KAP. Resultados: La mayoría de los pacientes encuestados (53,5%) se encontraban asintomáticos. La mayoría de ellos, tanto del grupo sintomático como asintomático, tenían un conocimiento adecuado sobre los síntomas y la transmisión de la enfermedad y la mayoría dijo que practicaban la cuarentena, el lavado frecuente de manos y el uso de mascarillas en las áreas públicas. Sin embargo, el reemplazo diario de mascarillas de tela fue más frecuente en el grupo asintomático, mientras que el reemplazo cada tres días fue más frecuente en el grupo sintomático. Finalmente, más de la mitad de los participantes admitieron haber estado en lugares concurridos, una práctica común entre los sintomáticos en comparación con los asintomáticos. Conclusiones: Este es el primer estudio CAP en Venezuela sobre COVID-19. El conocimiento y las prácticas entre los venezolanos podrían mejorarse fortaleciendo los programas de educación y capacitación. Esta información de la fase inicial de la pandemia en Venezuela puede contribuir al diseño de estrategias de promoción y prevención del COVID-19.


Subject(s)
COVID-19/prevention & control , COVID-19/transmission , Health Knowledge, Attitudes, Practice , Adult , Asymptomatic Infections/epidemiology , Cross-Sectional Studies , Crowding , Female , Hand Disinfection , Health Surveys/methods , Health Surveys/statistics & numerical data , Humans , Male , Masks/statistics & numerical data , Physical Distancing , Symptom Assessment , Triage , Venezuela/epidemiology
SELECTION OF CITATIONS
SEARCH DETAIL
...