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1.
Artículo en Inglés | MEDLINE | ID: mdl-34066512

RESUMEN

Increasing evidence shows that many infections of COVID-19 are asymptomatic, becoming a global challenge, since asymptomatic infections have the same infectivity as symptomatic infections. We developed a probabilistic model for estimating the proportion of undetected asymptomatic COVID-19 patients in the country. We considered two scenarios: one is conservative and the other is nonconservative. By combining the above two scenarios, we gave an interval estimation of 0.0001-0.0027 and in terms of the population, 5200-139,900 is the number of undetected asymptomatic cases in South Korea as of 2 February 2021. In addition, we provide estimates for total cases of COVID-19 in South Korea. Combination of undetected asymptomatic cases and undetected symptomatic cases to the number of confirmed cases (78,844 cases on 2 February 2021) shows that 0.17-0.42% (89,244-218,744) of the population have COVID-19. In conclusion, to control and understand the true ongoing reality of the pandemic, it is of outermost importance to focus on the ratio of undetected asymptomatic cases in the total population.


Asunto(s)
Infecciones Asintomáticas/epidemiología , Humanos , Modelos Estadísticos , Pandemias , República de Corea/epidemiología
2.
Pan Afr Med J ; 38: 217, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34046123

RESUMEN

Introduction: severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2); the causative agent of coronavirus disease 2019 (COVID-19), pandemics has remained to be a public health emergency of international concern. This ongoing pandemic has resulted in the death of millions of people globally. About one and a half thousand people have died due to this illness in Ethiopia. The clinical presentations of the disease vary with geography and populations. We therefore aimed at investigating the clinical characteristics of patients infected with SARS-CoV-2 in North-East Ethiopia. Methods: real time polymerase chain reaction (PCR) was conducted for 18,112 individuals suspected of SARS-CoV-2 infection during June 27 to October 20, 2020, at Woldia university COVID-19 testing center. Recorded data of 372 Ethiopians who tested positive for SARS-CoV-2 infection at Woldia university COVID-19 testing center were retrospectively extracted and analyzed using SPSS v25.0. A P-value of < 0.05 was considered statistically significant. Results: nearly 2.1% of the screened participants were found positive for SARS-CoV-2 infection. Among them, three fourth of SARS-CoV-2 infected patients were male, with an overall median age of 30 years. About 85% of the patients were asymptomatic. The most common clinical manifestations were cough (14.2%), followed by fever (11.0%) and headache (8.6%), whereas hypertension (1.6%), human immunodeficiency virus (HIV) (1.6%) diabetes mellitus (1.1%), and chronic respiratory diseases (1.1%) were relatively the most common comorbidities noted. The case-fatality ratio was found at 1.6%. Age and underlying comorbidities had a statistically significant association with severity and poor outcome of patients (P < 0.001). Conclusion: the finding from this study indicated that older age and people with underlying comorbidities are at high risk of having the severe disease and poor outcomes. Hence, appropriate care and priority should be given to these people to decrease the morbidity and mortality caused by this illness. The presence of higher asymptomatic infection is the possible indicator of potential asymptomatic transmissions within the community. This highlights the need for widespread testing, and contact tracing to flatten the transmission curve.


Asunto(s)
Infecciones Asintomáticas/epidemiología , /epidemiología , Adolescente , Adulto , Factores de Edad , Anciano , Anciano de 80 o más Años , /fisiopatología , Niño , Preescolar , Trazado de Contacto , Etiopía/epidemiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Reacción en Cadena en Tiempo Real de la Polimerasa , Estudios Retrospectivos , Factores de Riesgo , Índice de Severidad de la Enfermedad , Adulto Joven
3.
mSphere ; 6(3)2021 05 19.
Artículo en Inglés | MEDLINE | ID: mdl-34011679

RESUMEN

Information regarding the infectivity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in asymptomatic carriers is scarce. In order to determine the duration of infectivity and its correlation with reverse transcription-PCR (RT-PCR) results and time since initial positive PCR test in this population, we evaluated SARS-CoV-2 cell infectivity in nasopharyngeal samples longitudinally obtained from asymptomatic carriers who disembarked from a cruise ship during a COVID-19 outbreak. Of 166 nasopharyngeal samples collected from 39 asymptomatic carriers every 48 h until two consecutive negative PCR test results were obtained, SARS-CoV-2 was successfully isolated from 9 PCR-positive samples which were obtained from 7 persons (18%; 7/39). Viable viruses were isolated predominantly within 7 days after the initial positive PCR test, except for one person who shed viable virus until day 15. The median crossing point (Cp) value of RT-PCR of culture-positive samples was 24.6 (interquartile range [IQR], 20.4 to 25.8; range, 17.9 to 30.3), and Cp values were significantly associated with isolation of viable virus (odds ratio, 0.496; 95% confidence interval [CI], 0.329 to 0.747; P value, 0.001), which was consistent with existing data for symptomatic patients. Genome sequence analysis of SARS-CoV-2 samples consecutively obtained from a person who shed viable virus for 15 days identified the emergence of two novel single nucleotide variants (C8626T transition and C18452T transition) in the sample collected on day 15, with the latter corresponding to an amino acid substitution in nonstructural protein 14. The impact of these mutations on prolonged viable-virus shedding is unclear. These findings underscore the potential role of asymptomatic carriers in transmission.IMPORTANCE A growing number of studies suggest the potential role of asymptomatic SARS-CoV-2 carriers as a major driver of the COVID-19 pandemic; however, virological assessment of asymptomatic infection has largely been limited to reverse transcription-PCR (RT-PCR), which can be persistently positive without necessarily indicating the presence of viable virus (e.g., replication-competent virus). Here, we evaluated the infectivity of asymptomatic SARS-CoV-2 carriers by detecting SARS-CoV-2-induced cytopathic effects on Vero cells using longitudinally obtained nasopharyngeal samples from asymptomatic carriers. We show that asymptomatic carriers can shed viable virus until 7 days after the initial positive PCR test, with one outlier shedding until day 15. The crossing point (Cp) value of RT-PCR was the leading predictive factor for virus viability. These findings provide additional insights into the role of asymptomatic carriers as a source of transmission and highlight the importance of universal source control measures, along with isolation policy for asymptomatic carriers.


Asunto(s)
Infecciones Asintomáticas/epidemiología , Esparcimiento de Virus/fisiología , Adolescente , Adulto , Anciano , Animales , Línea Celular , Niño , Chlorocebus aethiops , Femenino , Genoma Viral/genética , Humanos , Masculino , Persona de Mediana Edad , Nasofaringe/virología , Células Vero , Secuenciación Completa del Genoma , Adulto Joven
4.
Sci Rep ; 11(1): 9545, 2021 05 05.
Artículo en Inglés | MEDLINE | ID: mdl-33953243

RESUMEN

A novel coronavirus (SARS-CoV-2) has spread worldwide and led to high disease burden around the world. This study aimed to explore the key parameters of SARS-CoV-2 infection and to assess the effectiveness of interventions to control the coronavirus disease 2019 (COVID-19). A susceptible-exposed-infectious-asymptomatic-recovered (SEIAR) model was developed for the assessment. The information of each confirmed case and asymptomatic infection was collected from Ningbo Center for Disease Control and Prevention (CDC) to calculate the key parameters of the model in Ningbo City, China. A total of 157 confirmed COVID-19 cases (including 51 imported cases and 106 secondary cases) and 30 asymptomatic infections were reported in Ningbo City. The proportion of asymptomatic infections had an increasing trend. The proportion of elder people in the asymptomatic infections was lower than younger people, and the difference was statistically significant (Fisher's Exact Test, P = 0.034). There were 22 clusters associated with 167 SARS-CoV-2 infections, among which 29 cases were asymptomatic infections, accounting for 17.37%. We found that the secondary attack rate (SAR) of asymptomatic infections was almost the same as that of symptomatic cases, and no statistical significance was observed (χ2 = 0.052, P = 0.819) by Kruskal-Wallis test. The effective reproduction number (Reff) was 1.43, which revealed that the transmissibility of SARS-CoV-2 was moderate. If the interventions had not been strengthened, the duration of the outbreak would have lasted about 16 months with a simulated attack rate of 44.15%. The total attack rate (TAR) and duration of the outbreak would increase along with the increasing delay of intervention. SARS-CoV-2 had moderate transmissibility in Ningbo City, China. The proportion of asymptomatic infections had an increase trend. Asymptomatic infections had the same transmissibility as symptomatic infections. The integrated interventions were implemented at different stages during the outbreak, which turned out to be exceedingly effective in China.


Asunto(s)
/epidemiología , /transmisión , Control de Infecciones/métodos , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Infecciones Asintomáticas/epidemiología , Número Básico de Reproducción , Niño , Preescolar , China/epidemiología , Ciudades , Femenino , Humanos , Incidencia , Lactante , Masculino , Persona de Mediana Edad , Modelos Teóricos , Adulto Joven
5.
JAMA Netw Open ; 4(5): e218824, 2021 05 03.
Artículo en Inglés | MEDLINE | ID: mdl-33938934

RESUMEN

Importance: Schools were closed intermittently across Hong Kong to control the COVID-19 outbreak, which led to significant physical and psychosocial problems among children and youths. Objective: To compare the clinical characteristics and sources of infection among children and youths with COVID-19 during the 3 waves of outbreaks in Hong Kong in 2020. Design, Setting, and Participants: This cross-sectional study involved children and youths aged 18 years or younger with COVID-19 in the 3 waves of outbreaks from January 23 through December 2, 2020. Data were analyzed from December 2020 through January 2021. Main Outcomes and Measures: Demographic characteristics, travel and contact histories, lengths of hospital stay, and symptoms were captured through the central electronic database. Individuals who were infected without recent international travel were defined as having domestic infections. Results: Among 397 children and youths confirmed with COVID-19 infections, the mean (SD) age was 9.95 (5.34) years, 220 individuals (55.4%) were male, and 154 individuals (38.8%) were asymptomatic. There were significantly more individuals who were infected without symptoms in the second wave (59 of 118 individuals [50.0%]) and third wave (94 of 265 individuals [35.5%]) than in the first wave (1 of 14 individuals [7.1%]) (P = .001). Significantly fewer individuals who were infected in the second and third waves, compared with the first wave, had fever (first wave: 10 individuals [71.4%]; second wave: 22 individuals [18.5%]; third wave: 98 individuals [37.0%]; P < .001) or cough (first wave: 6 individuals [42.9%]; second wave: 15 individuals [12.7%]; third wave: 52 individuals [19.6%]; P = .02). Among all individuals, 394 individuals (99.2%) had mild illness. One patient developed chilblains (ie, COVID toes), 1 patient developed multisystem inflammatory syndrome in children, and 1 patient developed post-COVID-19 autoimmune hemolytic anemia. In all 3 waves, 204 patients with COVID-19 (51.4%) had domestic infections. Among these individuals, 186 (91.2%) reported having a contact history with another individual with COVID-19, of which most (183 individuals [90.0%]) were family members. In the third wave, 18 individuals with domestic infections had unknown contact histories. Three schoolmates were confirmed with COVID-19 on the same day and were reported to be close contacts. Conclusions and Relevance: This cross-sectional study found that nearly all children and youths with COVID-19 in Hong Kong had mild illness. These findings suggest that household transmission was the main source of infection for children and youths with domestic infections and that the risk of being infected at school was small.


Asunto(s)
Infecciones Asintomáticas/epidemiología , Trazado de Contacto , Evaluación de Síntomas , Adolescente , /terapia , Niño , Trazado de Contacto/métodos , Trazado de Contacto/estadística & datos numéricos , Estudios Transversales , Transmisión de Enfermedad Infecciosa/prevención & control , Transmisión de Enfermedad Infecciosa/estadística & datos numéricos , Composición Familiar , Femenino , Hong Kong/epidemiología , Hospitalización/estadística & datos numéricos , Humanos , Masculino , Índice de Severidad de la Enfermedad , Evaluación de Síntomas/métodos , Evaluación de Síntomas/estadística & datos numéricos , Enfermedad Relacionada con los Viajes
6.
Lancet ; 397(10287): 1819-1829, 2021 05 15.
Artículo en Inglés | MEDLINE | ID: mdl-33964222

RESUMEN

BACKGROUND: Following the emergency use authorisation of the Pfizer-BioNTech mRNA COVID-19 vaccine BNT162b2 (international non-proprietary name tozinameran) in Israel, the Ministry of Health (MoH) launched a campaign to immunise the 6·5 million residents of Israel aged 16 years and older. We estimated the real-world effectiveness of two doses of BNT162b2 against a range of SARS-CoV-2 outcomes and to evaluate the nationwide public-health impact following the widespread introduction of the vaccine. METHODS: We used national surveillance data from the first 4 months of the nationwide vaccination campaign to ascertain incident cases of laboratory-confirmed SARS-CoV-2 infections and outcomes, as well as vaccine uptake in residents of Israel aged 16 years and older. Vaccine effectiveness against SARS-CoV-2 outcomes (asymptomatic infection, symptomatic infection, and COVID-19-related hospitalisation, severe or critical hospitalisation, and death) was calculated on the basis of incidence rates in fully vaccinated individuals (defined as those for whom 7 days had passed since receiving the second dose of vaccine) compared with rates in unvaccinated individuals (who had not received any doses of the vaccine), with use of a negative binomial regression model adjusted for age group (16-24, 25-34, 35-44, 45-54, 55-64, 65-74, 75-84, and ≥85 years), sex, and calendar week. The proportion of spike gene target failures on PCR test among a nationwide convenience-sample of SARS-CoV-2-positive specimens was used to estimate the prevelance of the B.1.1.7 variant. FINDINGS: During the analysis period (Jan 24 to April 3, 2021), there were 232 268 SARS-CoV-2 infections, 7694 COVID-19 hospitalisations, 4481 severe or critical COVID-19 hospitalisations, and 1113 COVID-19 deaths in people aged 16 years or older. By April 3, 2021, 4 714 932 (72·1%) of 6 538 911 people aged 16 years and older were fully vaccinated with two doses of BNT162b2. Adjusted estimates of vaccine effectiveness at 7 days or longer after the second dose were 95·3% (95% CI 94·9-95·7; incidence rate 91·5 per 100 000 person-days in unvaccinated vs 3·1 per 100 000 person-days in fully vaccinated individuals) against SARS-CoV-2 infection, 91·5% (90·7-92·2; 40·9 vs 1·8 per 100 000 person-days) against asymptomatic SARS-CoV-2 infection, 97·0% (96·7-97·2; 32·5 vs 0·8 per 100 000 person-days) against symptomatic COVID-19, 97·2% (96·8-97·5; 4·6 vs 0·3 per 100 000 person-days) against COVID-19-related hospitalisation, 97·5% (97·1-97·8; 2·7 vs 0·2 per 100 000 person-days) against severe or critical COVID-19-related hospitalisation, and 96·7% (96·0-97·3; 0·6 vs 0·1 per 100 000 person-days) against COVID-19-related death. In all age groups, as vaccine coverage increased, the incidence of SARS-CoV-2 outcomes declined. 8006 of 8472 samples tested showed a spike gene target failure, giving an estimated prevalence of the B.1.1.7 variant of 94·5% among SARS-CoV-2 infections. INTERPRETATION: Two doses of BNT162b2 are highly effective across all age groups (≥16 years, including older adults aged ≥85 years) in preventing symptomatic and asymptomatic SARS-CoV-2 infections and COVID-19-related hospitalisations, severe disease, and death, including those caused by the B.1.1.7 SARS-CoV-2 variant. There were marked and sustained declines in SARS-CoV-2 incidence corresponding to increasing vaccine coverage. These findings suggest that COVID-19 vaccination can help to control the pandemic. FUNDING: None.


Asunto(s)
/prevención & control , Vacunación Masiva , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Infecciones Asintomáticas/epidemiología , /mortalidad , Femenino , Hospitalización/estadística & datos numéricos , Humanos , Incidencia , Israel/epidemiología , Masculino , Persona de Mediana Edad , Pandemias , Vigilancia de la Población , ARN Mensajero , Adulto Joven
7.
Proc Natl Acad Sci U S A ; 118(21)2021 05 25.
Artículo en Inglés | MEDLINE | ID: mdl-33972412

RESUMEN

We analyze data from the fall 2020 pandemic response efforts at the University of Colorado Boulder, where more than 72,500 saliva samples were tested for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) using qRT-PCR. All samples were collected from individuals who reported no symptoms associated with COVID-19 on the day of collection. From these, 1,405 positive cases were identified. The distribution of viral loads within these asymptomatic individuals was indistinguishable from what has been previously observed in symptomatic individuals. Regardless of symptomatic status, ∼50% of individuals who test positive for SARS-CoV-2 seem to be in noninfectious phases of the disease, based on having low viral loads in a range from which live virus has rarely been isolated. We find that, at any given time, just 2% of individuals carry 90% of the virions circulating within communities, serving as viral "supercarriers" and possibly also superspreaders.


Asunto(s)
/virología , Portador Sano/virología , Infecciones Asintomáticas/epidemiología , /epidemiología , Portador Sano/diagnóstico , Portador Sano/epidemiología , Portador Sano/transmisión , Colorado/epidemiología , Hospitalización/estadística & datos numéricos , Humanos , Tamizaje Masivo/estadística & datos numéricos , /aislamiento & purificación , Saliva/virología , Universidades , Carga Viral , Virión
8.
Signal Transduct Target Ther ; 6(1): 181, 2021 05 10.
Artículo en Inglés | MEDLINE | ID: mdl-33972497

RESUMEN

Over 40% of the coronavirus disease 2019 (COVID-19) COVID-19 patients were asymptomatically infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the immune responses of these asymptomatic individuals is a critical factor for developing the strategy to contain the COVID-19 pandemic. Here, we determined the viral dynamics and antibody responses among 143 asymptomatic individuals identified in a massive screening of more than 5 million people in eight districts of Wuhan in May 2020. Asymptomatic individuals were admitted to the government-designated centralized sites in accordance with policy. The incidence rate of asymptomatic infection is ~2.92/100,000. These individuals had low viral copy numbers (peaked at 315 copies/mL) and short-lived antibody responses with the estimated diminish time of 69 days. The antibody responses in individuals with persistent SARS-CoV-2 infection is much longer with the estimated diminish time of 257 days. These results imply that the immune responses in the asymptomatic individuals are not potent enough for preventing SARS-CoV-2 re-infection, which has recently been reported in recovered COVID-19 patients. This casts doubt on the efficacy of forming "herd-immunity" through natural SARS-CoV-2 infection and urges for the development of safe and effective vaccines.


Asunto(s)
Anticuerpos Antivirales/inmunología , Infecciones Asintomáticas/epidemiología , Inmunidad/inmunología , Anciano , Anticuerpos Antivirales/sangre , Anticuerpos Antivirales/genética , /fisiopatología , China/epidemiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Pandemias , /patogenicidad
10.
Medicine (Baltimore) ; 100(15): e25230, 2021 Apr 16.
Artículo en Inglés | MEDLINE | ID: mdl-33847620

RESUMEN

ABSTRACT: Pediatric cases of coronavirus disease 2019 (COVID-19) have been reported. This meta-analysis was aimed at describing the clinical, laboratory, and imaging characteristics of children with COVID-19 based on published data of pediatric COVID-19 cases.Search of PubMed, Embase, Web of Sciences, Science Direct, and Google Scholar for articles published until December 14, 2020, that described the clinical, laboratory, and imaging features of children with COVID-19. Data were extracted independently by 2 authors. Random-effects meta-analysis models were used to report pooled results.Clinical data from 2874 children with COVID-19 from 37 articles were finally included for quantitative analyses. Fever (48.5%, 95% CI: 41.4%-55.6%) and cough (40.6%, 95% CI: 33.9%-47.5%) were the most common symptoms; asymptomatic infection and severe cases, respectively, accounted for 27.7% (95% CI: 19.7%-36.4%) patients and 1.1% of the 1933 patients included. Laboratory tests showed 5.5% (95% CI: 2.8%-8.9%) of the patients had lymphopenia. The pooled prevalence of leukopenia was 7.3% (95% CI: 3.4%-12.2%), and the C-reactive protein level was high in 14.0% (95% CI: 6.8%-22.8%). Chest computed tomography showed unilateral and bilateral lesions, and ground-glass opacity in 29.4% (95% CI: 24.8%-34.3%) and 24.7% (95% CI: 18.2%-31.6%), and 32.9% (95% CI: 25.3%-40.9%), respectively, and normal in approximately 36.0% (95% CI: 27.7%-44.7%).We found that children with COVID-19 had relatively mild disease, with quite a lot of asymptomatic infections and low rate of severe illness. Data from more regions are needed to determine the prevention and treatment strategies for children with COVID-19.


Asunto(s)
/métodos , Diagnóstico por Imagen/métodos , Evaluación de Síntomas/métodos , Infecciones Asintomáticas/epidemiología , /epidemiología , Niño , Salud Global/estadística & datos numéricos , Humanos , Pediatría , Índice de Severidad de la Enfermedad
11.
Int J Biol Sci ; 17(4): 1119-1124, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33867834

RESUMEN

With ongoing research, it was found that asymptomatic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection was widespread in coronavirus disease 2019 (COVID-19) populations. Studies have confirmed asymptomatic patients with COVID-19 have potential infectivity, and most of the transmission occurred before symptoms appear. Asymptomatic infection rates varied widely in different countries and regions. Identifying the asymptomatic infected persons and cutting off the infection source is an effective way to prevent the spread of this disease. However, asymptomatic patients have hidden clinical symptoms, and screening based only on the clinical symptoms of COVID-19 can easily lead to a missed diagnosis. Therefore, determining asymptomatic infection patients by SARS-CoV-2 nucleic acid testing is the gold standard. A series of prevention and control measures adopted by the Chinese government, especially the "Four Early" policy, have achieved outstanding achievements, which are worth learning from by other countries.


Asunto(s)
Infecciones Asintomáticas/epidemiología , /epidemiología , Infecciones Asintomáticas/terapia , /virología , China/epidemiología , Humanos , /patogenicidad
12.
Epidemiol Infect ; 149: e86, 2021 04 05.
Artículo en Inglés | MEDLINE | ID: mdl-33814022

RESUMEN

In this paper, we present a method to estimate the risk of reopening of schools illustrated with the case of the State of São Paulo, Brazil. The model showed that, although no death of children would result from the reopening of the schools in the three cities analysed, the risk of asymptomatic and symptomatic cases and secondary cases among teachers, school staff and relatives of the children is not negligible. Although the epidemic hit different regions with different intensities, our model shows that, for regions where the incidence profile is similar to the cities analysed, the risk of reopening of schools is still too high. This in spite of the fact that incidences in these cities were declining in the period of the time considered. Therefore, although we cannot extend the result to the entire country, the overall conclusion is valid for regions with a declining incidence and it is even more valid for regions where incidence is increasing. We assumed a very conservative level of infection transmissibility of children of just 10% as that of adults. In spite of the very low level of transmissibility is assumed, the number of secondary cases caused by infected children among teachers, school staff and relatives varied from 2 to 85. It is, therefore, too soon to have any degree of confidence that reopening of schools before the advent of a vaccine is the right decision to take. The purpose of our model and simulations is to provide a method to estimate the risk of school reopening, although we are sure it could be applied as a guide to public health strategies.


Asunto(s)
/epidemiología , Instituciones Académicas , Estudiantes/estadística & datos numéricos , Adulto , Infecciones Asintomáticas/epidemiología , Brasil/epidemiología , Niño , Preescolar , Brotes de Enfermedades/prevención & control , Familia , Humanos , Incidencia , Lactante , Modelos Teóricos , Maestros , Población Urbana
13.
Artículo en Inglés, Español | MEDLINE | ID: mdl-33858679

RESUMEN

INTRODUCTION: Due to its high transmissibility, measures aimed at reducing the spread of SARS CoV2 have become mandatory. Different organizations have recommended performing polymerase chain reaction tests (PCR) as part of the preoperative screening of surgical patients. We aimed to determine the performance of PCR testing to detect asymptomatic carriers. METHODS: Observational study carried out at a tertiary care center. We compared the results of preoperative real-time reverse-transcription-PCR test (RT-PCR) performed on a cohort of patients pending surgery with the results we would have expected assuming the epidemiological data released by government offices. RESULTS: We registered no positives in the 2,722 preoperative RT-PCR tests performed in our health care area between epidemiological Weeks 18 to 21, meaning a cumulative incidence trending to zero. Assuming public epidemiological data, the probabilistic projection of potential asymptomatic individuals ranged from 0.27*10e -4 (according to official data of new cases diagnosed by PCR) to 4.69*10e -4 if we assumed cases confirmed by IgG test in our province. Assuming a RT-PCR sensitivity of 95%, to obtain a positive result we should perform 38,461 and 2,028 tests respectively. CONCLUSIONS: In scenarios of very low prevalence and despite high sensitivity scores, indiscriminate preoperative RT-PCR screening is of a questionable effectiveness for detecting asymptomatic carriers. Our findings evidence the difficulty of establishing reliable predictive models for the episodic and rapidly evolving incidence of infections such as has characterized the SARS CoV2 pandemic.


Asunto(s)
Infecciones Asintomáticas/epidemiología , /diagnóstico , Pandemias , Cuidados Preoperatorios , /estadística & datos numéricos , Humanos , Incidencia , Estudios Retrospectivos , Sensibilidad y Especificidad
14.
JAMA Netw Open ; 4(4): e217498, 2021 04 01.
Artículo en Inglés | MEDLINE | ID: mdl-33885771

RESUMEN

Importance: Acute ischemic stroke (AIS) is a known neurological complication in patients with respiratory symptoms of COVID-19 infection. However, AIS has not been described as a late sequelae in patients without respiratory symptoms of COVID-19. Objective: To assess AIS experienced by adults 50 years or younger in the convalescent phase of asymptomatic COVID-19 infection. Design, Setting, and Participants: This case series prospectively identified consecutive male patients who received care for AIS from public health hospitals in Singapore between May 21, 2020, and October 14, 2020. All of these patients had laboratory-confirmed asymptomatic COVID-19 infection based on a positive SARS-CoV-2 serological (antibodies) test result. These patients were individuals from South Asian countries (India and Bangladesh) who were working in Singapore and living in dormitories. The total number of COVID-19 cases (54 485) in the worker dormitory population was the population at risk. Patients with ongoing respiratory symptoms or positive SARS-CoV-2 serological test results confirmed through reverse transcriptase-polymerase chain reaction nasopharyngeal swabs were excluded. Main Outcomes and Measures: Clinical course, imaging, and laboratory findings were retrieved from the electronic medical records of each participating hospital. The incidence rate of AIS in the case series was compared with that of a historical age-, sex-, and ethnicity-matched national cohort. Results: A total of 18 male patients, with a median (range) age of 41 (35-50) years and South Asian ethnicity, were included. The median (range) time from a positive serological test result to AIS was 54.5 (0-130) days. The median (range) National Institutes of Health Stroke Scale score was 5 (1-25). Ten patients (56%) presented with a large vessel occlusion, of whom 6 patients underwent intravenous thrombolysis and/or endovascular therapy. Only 3 patients (17%) had a possible cardiac source of embolus. The estimated annual incidence rate of AIS was 82.6 cases per 100 000 people in this study compared with 38.2 cases per 100 000 people in the historical age-, sex-, and ethnicity-matched cohort (rate ratio, 2.16; 95% CI, 1.36-3.48; P < .001). Conclusions and Relevance: This case series suggests that the risk for AIS is higher in adults 50 years or younger during the convalescent period of a COVID-19 infection without respiratory symptoms. Acute ischemic stroke could be part of the next wave of complications of COVID-19, and stroke units should be on alert and use serological testing, especially in younger patients or in the absence of traditional risk factors.


Asunto(s)
Infecciones Asintomáticas/epidemiología , Trombectomía/métodos , Terapia Trombolítica/métodos , Adulto , /diagnóstico , /métodos , Convalecencia , Registros Electrónicos de Salud/estadística & datos numéricos , Procedimientos Endovasculares/métodos , Humanos , Incidencia , /etnología , Masculino , Persona de Mediana Edad , Evaluación de Procesos y Resultados en Atención de Salud , Factores de Riesgo , /patogenicidad , Singapur/epidemiología , Migrantes/estadística & datos numéricos
15.
JAMA Netw Open ; 4(4): e217097, 2021 04 01.
Artículo en Inglés | MEDLINE | ID: mdl-33890990

RESUMEN

Importance: A significant proportion of COVID-19 transmission occurs silently during the presymptomatic and asymptomatic stages of infection. Children, although important drivers of silent transmission, are not included in the current COVID-19 vaccination campaigns. Objective: To estimate the benefits of identifying silent infections among children as a proxy for their vaccination. Design, Setting, and Participants: This study used an age-structured disease transmission model, parameterized with census data and estimates from published literature, to simulate the estimated synergistic effect of interventions in reducing attack rates during the course of 1 year among a synthetic population representative of the US demographic composition. The population included 6 age groups of 0 to 4, 5 to 10, 11 to 18, 19 to 49, 50 to 64, and 65 years or older based on US census data. Data were analyzed from December 12, 2020, to February 26, 2021. Exposures: In addition to the isolation of symptomatic cases within 24 hours of symptom onset, vaccination of adults was implemented to reach a 40% to 60% coverage during 1 year with an efficacy of 95% against symptomatic and severe COVID-19. Main Outcomes and Measures: The combinations of proportion and speed for detecting silent infections among children that would suppress future attack rates to less than 5%. Results: In the base-case scenarios with an effective reproduction number Re = 1.2, a targeted approach that identifies 11% of silent infections among children within 2 days and 14% within 3 days after infection would bring attack rates to less than 5% with 40% vaccination coverage of adults. If silent infections among children remained undetected, achieving the same attack rates would require an unrealistically high vaccination coverage (≥81%) of this age group, in addition to 40% vaccination coverage of adults. The estimated effect of identifying silent infections was robust in sensitivity analyses with respect to vaccine efficacy against infection and reduced susceptibility of children to infection. Conclusions and Relevance: In this simulation modeling study of a synthetic US population, in the absence of vaccine availability for children, a targeted approach to rapidly identify silent COVID-19 infections in this age group was estimated to significantly mitigate disease burden. These findings suggest that without measures to interrupt transmission chains from silent infections, vaccination of adults is unlikely to contain the outbreaks in the near term.


Asunto(s)
Infecciones Asintomáticas/epidemiología , Número Básico de Reproducción/estadística & datos numéricos , Transmisión de Enfermedad Infecciosa , Cobertura de Vacunación/estadística & datos numéricos , Vacunación , Adulto , Anciano , /prevención & control , /provisión & distribución , Niño , Simulación por Computador , Transmisión de Enfermedad Infecciosa/prevención & control , Transmisión de Enfermedad Infecciosa/estadística & datos numéricos , Femenino , Humanos , Recién Nacido , Masculino , Estados Unidos/epidemiología , Vacunación/métodos , Vacunación/normas
16.
BMC Infect Dis ; 21(1): 388, 2021 Apr 26.
Artículo en Inglés | MEDLINE | ID: mdl-33902477

RESUMEN

BACKGROUND: One of the leading long-term complications of type 2 diabetes mellitus (T2DM) includes renal dysfunction and urinary tract infections (UTI) which are considered to be prevalent in uncontrolled diabetes. Moreover, physiological factors like age, gender, duration of diabetes, other diabetic complications like neuropathy, autonomic neuropathy and glycosuria are also considered as predisposing factors for increased prevalence of UTI in diabetes which can be symptomatic or asymptomatic. METHODS: This was a cross-sectional, multi-centre study including diabetic patients from 12 clinical sites spread across major cities of Pakistan. The inclusion criteria were adult Pakistani population of age between 18 to 75 years both genders and suffering from T2DM irrespective of duration. A detailed clinical history of the past 3 months was recorded and, biochemical investigations of blood samples were conducted. Urine culture analysis performed identified the type of pathogen present and was done only for asymptomatic patients. RESULTS: A total of 745 type 2 diabetic patients were initially screened, out of 545 patients considered for final analysis 501 (91.92%) were negative and the rest 44 (8.08%) had positive urine culture. Female gender had a significantly higher proportion of positive urine culture (77.27%, p-value< 0.001). Body mass index and mean age had insignificant distribution among the two groups of positive and negative urine culture, with age 40-59 years having higher proportion (70.45%) in the positive group. Escherichia coli was detected in most of the positive samples (52.3%). All bacterial samples were found resistant to Ciprofloxacin. CONCLUSION: Diabetic Pakistani muslim female patients are identified to be at high risk of suffering from asymptomatic UTI and age more than 40 years is an important risk factor. Escherichia coli was the most common causative organism among people living in this geographical area.


Asunto(s)
Infecciones Asintomáticas/epidemiología , Diabetes Mellitus Tipo 2/complicaciones , Infecciones por Escherichia coli/epidemiología , Infecciones por Escherichia coli/etiología , Escherichia coli/aislamiento & purificación , Islamismo , Infecciones Urinarias/epidemiología , Infecciones Urinarias/etiología , Adolescente , Adulto , Factores de Edad , Anciano , Estudios Transversales , Infecciones por Escherichia coli/microbiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Pakistán/epidemiología , Prevalencia , Factores de Riesgo , Factores Sexuales , Urinálisis , Infecciones Urinarias/microbiología , Infecciones Urinarias/orina , Adulto Joven
17.
Infect Dis Poverty ; 10(1): 56, 2021 Apr 26.
Artículo en Inglés | MEDLINE | ID: mdl-33902695

RESUMEN

BACKGROUND: As one of the non-pharmacological interventions to control the transmission of COVID-19, determining the quarantine duration is mainly based on the accurate estimates of the incubation period. However, patients with coarse information of the exposure date, as well as infections other than the symptomatic, were not taken into account in previously published studies. Thus, by using the statistical method dealing with the interval-censored data, we assessed the quarantine duration for both common and uncommon infections. The latter type includes the presymptomatic, the asymptomatic and the recurrent test positive patients. METHODS: As of 10 December 2020, information on cases have been collected from the English and Chinese databases, including Pubmed, Google scholar, CNKI (China National Knowledge Infrastructure) and Wanfang. Official websites and medias were also searched as data sources. All data were transformed into doubly interval-censored and the accelerated failure time model was applied. By estimating the incubation period and the time-to-event distribution of worldwide COVID-19 patients, we obtain the large percentiles for determining and suggesting the quarantine policies. For symptomatic and presymptomatic COVID-19 patients, the incubation time is the duration from exposure to symptom onset. For the asymptomatic, we substitute the date of first positive result of nucleic acid testing for that of symptom onset. Furthermore, the time from hospital discharge or getting negative test result to the positive recurrence has been calculated for recurrent positive patients. RESULTS: A total of 1920 laboratory confirmed COVID-19 cases were included. Among all uncommon infections, 34.1% (n = 55) of them developed symptoms or were identified beyond fourteen days. Based on all collected cases, the 95th and 99th percentiles were estimated to be 16.2 days (95% CI 15.5-17.0) and 22.9 days (21.7‒24.3) respectively. Besides, we got similar estimates based on merely symptomatic and presymptomatic infections as 15.1 days (14.4‒15.7) and 21.1 days (20.0‒22.2). CONCLUSIONS: There are a certain number of infected people who require longer quarantine duration. Our findings well support the current practice of the extended active monitoring. To further prevent possible transmissions induced and facilitated by such infectious outliers after the 14-days quarantine, properly prolonging the quarantine duration could be prudent for high-risk scenarios and in regions with insufficient test resources.


Asunto(s)
/prevención & control , Cuarentena/métodos , /fisiología , Adolescente , Adulto , Anciano , Enfermedades Asintomáticas/epidemiología , Infecciones Asintomáticas/epidemiología , Portador Sano/epidemiología , Niño , Preescolar , Femenino , Humanos , Lactante , Recién Nacido , Periodo de Incubación de Enfermedades Infecciosas , Masculino , Persona de Mediana Edad , Modelos Estadísticos , Factores de Tiempo , Adulto Joven
18.
Cancer Treat Res Commun ; 27: 100346, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33756172

RESUMEN

OBJECTIVE: Several factors raise concern for increased risk of COVID-19 in cancer patients. While there is strong support for testing symptomatic patients. The benefit of routine testing of asymptomatic patients remains contentious. We aim to evaluate the prevalence of asymptomatic COVID-19 infection in cancer patients. METHODS: Between June 1 and September 3, 2020, we obtained nasopharyngeal swab from asymptomatic cancer patients who were visiting a single tertiary-care cancer center, and tested the specimen for the presence or absence of SARS-CoV-2 RNA. We performed a descriptive statistic of data RESULTS: We tested a total of 80 patients, of which 3 (3.75%) were found positive for COVID-19. A significant proportion of the tested patients were on active immunosuppressive or immunomodulatory treatment, cytotoxic chemotherapy (n = 34), and immunotherapy (n = 16). However, all three COVID-19 positive patients were only actively on hormonal therapy. All three patients observed a minimum of 2 weeks home quarantine. None of the patients developed symptoms upon follow up and no changes were required to their treatment plan. CONCLUSIONS: Despite published evidence that cancer patients may be at increased risk of severe COVID -19 infection, our data suggest that some infected cancer patients are asymptomatic. The overall prevalence of asymptomatic COVID-19 infection in this population of cancer patients was similar to that in the general population. Therefore, since asymptomatic infections are not uncommon in patients with cancer, we recommend universal COVID-19 testing to help guide treatment decisions and prevent the spread of the disease.


Asunto(s)
Infecciones Asintomáticas/terapia , Neoplasias/terapia , Centros de Atención Terciaria , Adulto , Anciano , Anciano de 80 o más Años , Infecciones Asintomáticas/epidemiología , /virología , Estudios Transversales , Femenino , Humanos , Masculino , Persona de Mediana Edad , Neoplasias/diagnóstico , Neoplasias/epidemiología , Ciudad de Nueva York/epidemiología , Pandemias , Prevalencia , Estudios Prospectivos , ARN Viral/análisis , ARN Viral/genética , /fisiología
19.
PLoS One ; 16(3): e0248273, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33725000

RESUMEN

The COVID-19 outbreak on the Diamond Princess (DP) cruise ship has provided empirical data to study the transmission potential of COVID-19 with the presence of pre/asymptomatic cases. We studied the changes in R0 on DP from January 21 to February 19, 2020 based on chain binomial models under two scenarios: no quarantine assuming a random mixing condition, and quarantine of passengers in cabins-passengers may get infected either by an infectious case in a shared cabin or by pre/asymptomatic crew who continued to work. Estimates of R0 at the beginning of the epidemic were 3.27 (95% CI, 3.02-3.54) and 3.78 (95% CI, 3.49-4.09) respectively for serial intervals of 5 and 6 days; and when quarantine started, with the reported asymptomatic ratio 0.505, R0 rose to 4.18 (95%CI, 3.86-4.52) and 4.73 (95%CI, 4.37-5.12) respectively for passengers who might be exposed to the virus due to pre/asymptomatic crew. Results confirm that the higher the asymptomatic ratio is, the more infectious contacts would happen. We find evidence to support a US CDC report that "a high proportion of asymptomatic infections could partially explain the high attack rate among cruise ship passengers and crew." Our study suggests that if the asymptomatic ratio is high, the conventional quarantine procedure may not be effective to stop the spread of virus.


Asunto(s)
Infecciones Asintomáticas/epidemiología , Modelos Estadísticos , /epidemiología , /virología , Brotes de Enfermedades , Humanos , Cuarentena , Navíos
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