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1.
PLoS One ; 17(1): e0262169, 2022.
Article in English | MEDLINE | ID: covidwho-1633137

ABSTRACT

Current SARS-CoV-2 serological assays generate discrepant results, and the longitudinal characteristics of antibodies targeting various antigens after asymptomatic to mild COVID-19 are yet to be established. This longitudinal cohort study including 1965 healthcare workers, of which 381 participants exhibited antibodies against the SARS-CoV-2 spike antigen at study inclusion, reveal that these antibodies remain detectable in most participants, 96%, at least four months post infection, despite having had no or mild symptoms. Virus neutralization capacity was confirmed by microneutralization assay in 91% of study participants at least four months post infection. Contrary to antibodies targeting the spike protein, antibodies against the nucleocapsid protein were only detected in 80% of previously anti-nucleocapsid IgG positive healthcare workers. Both anti-spike and anti-nucleocapsid IgG levels were significantly higher in previously hospitalized COVID-19 patients four months post infection than in healthcare workers four months post infection (p = 2*10-23 and 2*10-13 respectively). Although the magnitude of humoral response was associated with disease severity, our findings support a durable and functional humoral response after SARS-CoV-2 infection even after no or mild symptoms. We further demonstrate differences in antibody kinetics depending on the antigen, arguing against the use of the nucleocapsid protein as target antigen in population-based SARS-CoV-2 serological surveys.


Subject(s)
COVID-19/pathology , Immunity, Humoral , Adult , Antibodies, Neutralizing/blood , Antibodies, Neutralizing/immunology , Antibodies, Viral/blood , Antibodies, Viral/immunology , Asymptomatic Infections/epidemiology , COVID-19/immunology , COVID-19/virology , Female , Health Personnel , Humans , Immunoglobulin G/blood , Immunoglobulin G/immunology , Longitudinal Studies , Male , Middle Aged , Nucleocapsid/immunology , SARS-CoV-2/isolation & purification , SARS-CoV-2/metabolism , Severity of Illness Index , Spike Glycoprotein, Coronavirus/immunology
2.
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
3.
PLoS One ; 17(1): e0252994, 2022.
Article in English | MEDLINE | ID: covidwho-1622325

ABSTRACT

The global impact of coronavirus disease 2019 (COVID-19) is unprecedented, and many control and prevention measures have been implemented to test for and trace COVID-19. However, invisible-spreaders, who are associated with nucleic acid detection and asymptomatic infections, have received insufficient attention in the current COVID-19 control efforts. In this paper, we analyze the time series infection data for Italy, Germany, Brazil, India and Sweden since the first wave outbreak to address the following issues through a series of experiments. We conclude that: 1) As of June 1, 2020, the proportion of invisible-spreaders is close to 0.4% in Sweden, 0.8% in early Italy and Germany, and 0.4% in the middle and late stages. However, in Brazil and India, the proportion still shows a gradual upward trend; 2) During the spread of this pandemic, even a slight increase in the proportion of invisible-spreaders could have large implications for the health of the community; and 3) On resuming work, the pandemic intervention measures will be relaxed, and invisible-spreaders will cause a new round of outbreaks.


Subject(s)
Asymptomatic Infections/epidemiology , COVID-19/transmission , Brazil/epidemiology , COVID-19/diagnosis , COVID-19/epidemiology , COVID-19/virology , Germany/epidemiology , Humans , India/epidemiology , Italy/epidemiology , Models, Theoretical , Pandemics , SARS-CoV-2/isolation & purification , Sweden/epidemiology
4.
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
9.
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
11.
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
12.
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
13.
Comput Math Methods Med ; 2021: 5384481, 2021.
Article in English | MEDLINE | ID: covidwho-1476872

ABSTRACT

In this study we propose a Coronavirus Disease 2019 (COVID-19) mathematical model that stratifies infectious subpopulations into: infectious asymptomatic individuals, symptomatic infectious individuals who manifest mild symptoms and symptomatic individuals with severe symptoms. In light of the recent revelation that reinfection by COVID-19 is possible, the proposed model attempt to investigate how reinfection with COVID-19 will alter the future dynamics of the recent unfolding pandemic. Fitting the mathematical model on the Kenya COVID-19 dataset, model parameter values were obtained and used to conduct numerical simulations. Numerical results suggest that reinfection of recovered individuals who have lost their protective immunity will create a large pool of asymptomatic infectious individuals which will ultimately increase symptomatic individuals with mild symptoms and symptomatic individuals with severe symptoms (critically ill) needing urgent medical attention. The model suggests that reinfection with COVID-19 will lead to an increase in cumulative reported deaths. Comparison of the impact of non pharmaceutical interventions on curbing COVID19 proliferation suggests that wearing face masks profoundly reduce COVID-19 prevalence than maintaining social/physical distance. Further, numerical findings reveal that increasing detection rate of asymptomatic cases via contact tracing, testing and isolating them can drastically reduce COVID-19 surge, in particular individuals who are critically ill and require admission into intensive care.


Subject(s)
COVID-19/transmission , Models, Biological , Pandemics , SARS-CoV-2 , Asymptomatic Infections/epidemiology , COVID-19/epidemiology , COVID-19/prevention & control , Computational Biology , Computer Simulation , Contact Tracing , Databases, Factual , Disease Susceptibility , Humans , Kenya/epidemiology , Masks , Pandemics/prevention & control , Pandemics/statistics & numerical data , Physical Distancing , Reinfection/epidemiology , Reinfection/transmission , SARS-CoV-2/immunology
14.
Medicine (Baltimore) ; 100(30): e26748, 2021 Jul 30.
Article in English | MEDLINE | ID: covidwho-1475911

ABSTRACT

ABSTRACT: The aim of this study was to retrospectively analyze the clinical data of COVID-19 patients with different severity during February 2020 in Wuxi, China.The present retrospective study included a total of 60 cases who were diagnosed as COVID-19 patients and hospitalized in the Wuxi Fifth People's Hospital during February 2020 to March 2020. Among all patients 14 cases were asymptomatic, 25 cases were with mild stage, 13 cases were with moderate stage, and 8 cases were with severe stage. Basic clinical data as well as clinical characteristics, including temperature, respiratory rate, heart rate, blood gas analysis data, whole blood test data, and the prognosis condition, were collected and analyzed. Statistical analysis was conducted in different severity stage patients.Among the patients, the median temperature gradually increased from the asymptomatic to the severe patients and the median age increased from the mild to the severe patients with statistical difference. The hospitalization duration was the highest in severe patients. Higher heart rate, as well as lower oxygen partial pressure and oxygenation index were observed in severe patients than the other groups. Besides, higher CRP and globulin levels after admission were found in severe patients, and were gradually increased from the asymptomatic patients to the severe patients. On the contrary, the lymphocyte ratio and count was significant lower in severe patients. We also observed higher D-Dimer levels in the severe patients and the difference was statistical. Among all patients, 2 cases (3.33%) died and other patients were all cured after treatment.Statistical difference was mainly found mainly in age, hospitalization duration, temperature, CRP levels, O2 partial pressure and oxygenation index, globulin, lymphocyte ratio, and D-Dimer in patients with different severity. The higher CRP levels, lower O2 partial pressure and oxygenation index, higher globulin, lower lymphocyte ratio, and higher D-Dimer might be associated with the patients' severity.


Subject(s)
COVID-19/pathology , Adolescent , Adult , Aged , Asymptomatic Infections/epidemiology , COVID-19/epidemiology , COVID-19/therapy , Child , Child, Preschool , China/epidemiology , Female , Heart Rate , Humans , Male , Middle Aged , Oxygen/blood , Retrospective Studies , Severity of Illness Index , Young Adult
15.
Nat Commun ; 12(1): 6032, 2021 10 15.
Article in English | MEDLINE | ID: covidwho-1469967

ABSTRACT

Vaccine breakthrough SARS-CoV-2 infection has been monitored in 3720 healthcare workers receiving 2 doses of BNT162b2. SARS-CoV-2 infection is detected in 33 subjects, with a 100-day cumulative incidence of 0.93%. Vaccine protection against acquisition of SARS-CoV-2 infection is 83% (95%CI: 58-93%) in the overall population and 93% (95%CI: 69-99%) in SARS-CoV-2-experienced subjects, when compared with a non-vaccinated control group from the same Institution, in which SARS-CoV-2 infection occurs in 20/346 subjects (100-day cumulative incidence: 5.78%). The infection is symptomatic in 16 (48%) vaccinated subjects vs 17 (85%) controls (p = 0.01). All analyzed patients, in whom the amount of viral RNA was sufficient for genome sequencing, results infected by the alpha variant. Antibody and T-cell responses are not reduced in subjects with breakthrough infection. Evidence of virus transmission, determined by contact tracing, is observed in two (6.1%) cases. This real-world data support the protective effect of BNT162b2 vaccine. A triple antigenic exposure, such as two-dose vaccine schedule in experienced subjects, may confer a higher protection.


Subject(s)
Asymptomatic Infections/epidemiology , COVID-19 Vaccines/administration & dosage , COVID-19/diagnosis , Health Personnel/statistics & numerical data , SARS-CoV-2/pathogenicity , Antibodies, Viral/blood , COVID-19/epidemiology , COVID-19/prevention & control , COVID-19/virology , COVID-19 Nucleic Acid Testing/statistics & numerical data , Case-Control Studies , Female , Humans , Immunization Schedule , Incidence , Male , Prospective Studies , RNA, Viral/genetics , RNA, Viral/isolation & purification , SARS-CoV-2/genetics , SARS-CoV-2/immunology , SARS-CoV-2/isolation & purification , Severity of Illness Index
16.
JAMA Netw Open ; 4(10): e2128757, 2021 10 01.
Article in English | MEDLINE | ID: covidwho-1460118

ABSTRACT

Importance: Recent data suggest a relatively low incidence of COVID-19 among children. The possible role that children attending primary school may play in the transmission of SARS-CoV-2 remains poorly understood. Objective: To gain a better understanding of the possible role of children in the transmission of SARS-CoV-2. Design, Setting, and Participants: This prospective cohort study was conducted from September 21 to December 31, 2020, in a primary school in Liège, Belgium, among a volunteer sample of 181 children, parents, and school employees. Exposures: Participants were tested for SARS-CoV-2 infection once a week for 15 weeks through throat washing, performed with 5 mL of saline and collected in a sterile tube after approximately 30 seconds of gargling. Quantitative reverse transcription-polymerase chain reaction was performed to detect SARS-CoV-2 infection. Main Outcomes and Measures: In case of test positivity, participants were asked to complete a questionnaire aimed at determining the timing of symptom onset and symptom duration. SARS-CoV-2 genetic sequencing was also performed. Confirmed cases were linked based on available information on known contacts and viral sequences. Results: A total of 181 individuals participated in this study, including 63 children (34 girls [54.0%]; mean [SD] age, 8.6 [1.9] years [range, 5-13 years]) and 118 adults (75 women [63.6%]; mean [SD] age, 42.5 [5.7] years [range, 30-59 years]). Forty-five individuals (24.9%) tested positive: 13 children (20.6%; 95% CI, 10.6%-30.6%) and 32 adults (27.1%; 95% CI, 19.1%-35.7%) (P = .34). Children were more often asymptomatic compared with adults (6 [46.2%; 95% CI, 19.1%-73.3%] vs 4 of 31 [12.9%; 95% CI, 1.3%-24.5%]; P = .04). The median duration of symptoms was shorter in children than in adults (0.00 days [IQR, 0.00-1.00 days] vs 15.00 days [IQR, 7.00-22.00 days]). A reconstruction of the outbreak revealed that most transmission events occurred between teachers and between children within the school. Of the observed household transmission events, most seemed to have originated from a child or teacher who acquired the infection at school. Conclusions and Relevance: Despite the implementation of several mitigation measures, the incidence of COVID-19 among children attending primary school in this study was comparable to that observed among teachers and parents. Transmission tree reconstruction suggests that most transmission events originated from within the school. Additional measures should be considered to reduce the transmission of SARS-CoV-2 at school, including intensified testing.


Subject(s)
COVID-19 Testing , COVID-19/prevention & control , COVID-19/transmission , Mass Screening , Adolescent , Adult , Asymptomatic Infections/epidemiology , Belgium/epidemiology , COVID-19/diagnosis , COVID-19/epidemiology , Child , Child, Preschool , Contact Tracing , Disease Outbreaks , Female , Humans , Incidence , Logistic Models , Male , Middle Aged , Prospective Studies , School Teachers , Schools
18.
PLoS One ; 16(9): e0257452, 2021.
Article in English | MEDLINE | ID: covidwho-1440988

ABSTRACT

OBJECTIVES: A few studies on antibody testing have focused on asymptomatic or mild coronavirus disease 2019 (COVID-19) patients with low initial anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody responses. Anti-SARS-CoV-2 antibody-testing performance was evaluated using blood samples from asymptomatic or mild COVID-19 patients. METHODS: Blood samples were collected from 143 COVID-19 patients during an outbreak on a cruise ship 3 weeks after diagnosis. Simultaneously, a follow-up SARS-CoV-2 genetic test was performed. Samples stored before the COVID-19 pandemic were also used to evaluate the lateral flow immunochromatographic assay (LFA) and electrochemiluminescence immunoassay (ECLIA). Titers of anti-SARS-CoV-2 IgM and IgG antibodies against the nucleocapsid and spike proteins were measured using the enzyme-linked immunosorbent assay to confirm which antibodies were influenced on LFA- and ECLIA- false-negative result in crew-member samples. RESULTS: Sensitivity, specificity, positive-predictive, and negative-predictive values of LFA-detected IgM antibodies were 0.231, 1.000, 1.000, and 0.613, respectively; those of LFA-detected IgG antibodies were 0.483, 0.989, 0.972, and 0.601, respectively; and those of ECLIA-detected total antibodies were 0.783, 1.000, 1.000, and 0.848, respectively. All antibody titers measured using ELISA were significantly lower in blood samples with negative results than in those with positive results in both LFA and ECLIA. In the patients with negative results from the follow-up genetic testing, IgM-, IgG-, and total-antibody positivity rates were 22.9%, 47.6%, and 72.4%, respectively. CONCLUSIONS: These findings suggest that anti-SARS-CoV-2 antibody testing has lower performance in asymptomatic or mild COVID-19 patients than required in the guidelines.


Subject(s)
COVID-19 Serological Testing/methods , COVID-19/diagnosis , COVID-19/immunology , Adult , Antibodies, Viral/immunology , Asymptomatic Infections/epidemiology , COVID-19 Serological Testing/trends , COVID-19 Testing/methods , Disease Outbreaks/prevention & control , Enzyme-Linked Immunosorbent Assay/methods , Female , Humans , Immunoassay/methods , Immunoglobulin G/blood , Immunoglobulin M/blood , Male , Middle Aged , Retrospective Studies , SARS-CoV-2/immunology , Sensitivity and Specificity , Ships
19.
J Med Virol ; 93(10): 5873-5879, 2021 Oct.
Article in English | MEDLINE | ID: covidwho-1432420

ABSTRACT

Population-based immunoglobulin G (IgG) seroprevalence studies in asymptomatic individuals in Latin America are scarce. The objective of the study was to estimate the prevalence and geographic distribution of IgG antibodies induced by natural SARS-CoV-2 infection in asymptomatic adults, 5-8 months after the first case was reported in a northeastern state of Mexico. This was a population-based cross-sectional study carried out in Nuevo Leon during August-November 2020. Individuals ≥18 years with no previous diagnosis or symptoms suggestive of COVID-19 were consecutively screened in one of the busiest subway stations. Also, a search for eligible individuals was done from house-to-house, after selecting densely populated geographic sectors of each of the municipalities of the metropolitan area (n = 4495). The IgG antibodies to SARS-CoV-2 nucleocapsid protein were analyzed. The IgG antibody positivity rate was 27.1% (95% confidence interval [CI]: 25.8, 28.4); there were no differences by sex or age (p > 0.05). Analysis by month showed a gradual increase from 11.9% (August) to 31.9% (November); Week 39 had the highest positivity rate (42.2%, 95% CI: 34.2, 50.7). Most people did not have evidence of previous SARS-CoV-2 infection. Preventive measures and promotion of the COVID-19 vaccine should be strengthened.


Subject(s)
Antibodies, Viral/blood , Asymptomatic Infections/epidemiology , COVID-19/epidemiology , Immunoglobulin G/blood , SARS-CoV-2/immunology , Adult , COVID-19/diagnosis , Coronavirus Nucleocapsid Proteins/immunology , Cross-Sectional Studies , Female , Humans , Male , Mexico/epidemiology , Middle Aged , Phosphoproteins/immunology , Prevalence , Seroepidemiologic Studies
20.
Ghana Med J ; 54(4 Suppl): 16-22, 2020 Dec.
Article in English | MEDLINE | ID: covidwho-1436190

ABSTRACT

Introduction: COVID-19 is a new disease, knowledge on the mode of transmission and clinical features are still evolving, new tests are being developed with inherent challenges regarding interpretation of tests results. There is generally, a gap in knowledge on the virus globally as the pandemic evolves and in Ghana, there is dearth of information and documentation on the clinical characteristics of the virus. With these in mind, we set out to profile the initial cohort of COVID-19 patients who recovered in Ghana. Methods: We reviewed clinical records of all confirmed cases of COVID-19 who had recovered from the two main treatment centres in Accra, Ghana. Descriptive data analysis was employed and presented in simple and relational tables. Independent t-test and ANOVA were used to determine differences in the mean age of the sexes and the number of days taken for the first and second retesting to be done per selected patient characteristics. Results: Of the 146 records reviewed, 54% were male; mean age of patients was 41.9 ± 17.5 years, nearly half were asymptomatic, with 9% being severely ill. The commonest presenting symptoms were cough (22.6%), headache (13%) and sore throat (11%) while the commonest co-morbidities were hypertension (25.3%), diabetes mellitus (14%) and heart disease (3.4%). Conclusion: COVID-19 affected more males than females; nearly half of those infected were asymptomatic. Cough, headache and sore throat were the commonest symptoms and mean duration from case confirmation to full recovery was 19 days. Further research is required as pandemic evolves. Funding: None declared.


Subject(s)
Asymptomatic Infections/epidemiology , COVID-19/epidemiology , SARS-CoV-2 , Adult , Age Distribution , Analysis of Variance , COVID-19/virology , Cohort Studies , Cough/epidemiology , Cough/virology , Female , Ghana/epidemiology , Headache/epidemiology , Headache/virology , Humans , Male , Middle Aged , Pharyngitis/epidemiology , Pharyngitis/virology , Sex Distribution
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