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Frontiers in Public Health 2020Asymptomatic cases of SARS-CoV-2 can be unknown carriers magnifying the transmission of COVID-19. This study appraised the frequency of asymptomatic individuals and... (Meta-Analysis)
Meta-Analysis
Asymptomatic cases of SARS-CoV-2 can be unknown carriers magnifying the transmission of COVID-19. This study appraised the frequency of asymptomatic individuals and estimated occurrence by age group and gender by reviewing the existing published data on asymptomatic people with COVID-19. Three electronic databases, PubMed, Embase, and Web of Science (WoS), were used to search the literature following the guidelines of Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). The study population for this review included asymptomatic individuals infected with SARS-CoV-2 reported in original articles published up to 30 April 2020. A random effects model was applied to analyze pooled data on the prevalence of asymptomatic cases among all COVID-19 patients and also by age and gender. From the meta-analysis of 16 studies, comprising 2,788 SARS-CoV-2 infected patients, the pooled prevalence according to the random effect size of asymptomatic cases was 48.2% (95% CI, 30-67%). Of the asymptomatic cases, 55.5% (95% CI, 43.6-66.8%) were female and 49.6% (95% CI, 20.5-79.1%) were children. Children and females were more likely to present as asymptomatic COVID-19 cases and could act as unknown carriers of SARS-CoV-2. Symptom-based screening might fail to identify all SARS-CoV-2 infections escalating the threat of global spread and impeding containment. Therefore, a mass surveillance system to track asymptomatic cases is critical, with special attention to females and children.
Topics: Age Factors; COVID-19; Carrier State; Humans; Mass Screening; SARS-CoV-2; Sex Factors
PubMed: 33553089
DOI: 10.3389/fpubh.2020.587374 -
Medicina (Kaunas, Lithuania) Sep 2023Asymptomatic bacteriuria (ASB) is prevalent in kidney transplant recipients (KTRs) and is hypothesized to heighten the risk of subsequent urinary tract infections... (Meta-Analysis)
Meta-Analysis Review
Asymptomatic bacteriuria (ASB) is prevalent in kidney transplant recipients (KTRs) and is hypothesized to heighten the risk of subsequent urinary tract infections (UTIs). Whether antibiotic treatment of ASB in KTRs is beneficial has not been elucidated. We carried out a systematic review and meta-analysis of all randomized controlled trials (RCTs) and quasi-RCTs that examined the merits of managing asymptomatic bacteriuria in KTRs. The primary outcomes were rates of symptomatic urinary tract infections (UTIs) and antimicrobial resistance. : Five studies encompassing 566 patients were included. No significant difference in symptomatic UTI rates was found between antibiotics and no treatment groups (relative risk (RR) 1.05, 95% confidence interval (CI) = 0.78-1.41), with moderate heterogeneity (I = 36%). Antibiotic treatment was found to present an uncertain risk for the development of drug-resistant strains (RR = 1.51, 95% CI = 0.95-2.40, I = 0%). In all trials, no significant difference between study arms was demonstrated regarding patient and graft outcomes, such as graft function, graft loss, hospitalization due to UTI, all-cause mortality, or acute rejection. : The practice of screening and treating kidney transplant patients for asymptomatic bacteriuria does not curtail the incidence of future symptomatic UTIs, increase antimicrobial resistance, or affect graft outcomes. Whether early treatment of ASB after kidney transplantation (<2 months) is beneficial requires more RCTs.
Topics: Humans; Bacteriuria; Kidney Transplantation; Randomized Controlled Trials as Topic; Anti-Bacterial Agents; Hospitalization
PubMed: 37763718
DOI: 10.3390/medicina59091600 -
Epidemiology (Cambridge, Mass.) Nov 2015The fraction of persons with influenza virus infection, who do not report any signs or symptoms throughout the course of infection is referred to as the asymptomatic... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
The fraction of persons with influenza virus infection, who do not report any signs or symptoms throughout the course of infection is referred to as the asymptomatic fraction.
METHODS
We conducted a systematic review and meta-analysis of published estimates of the asymptomatic fraction of influenza virus infections. We found that estimates of the asymptomatic fraction were reported from two different types of studies: first, outbreak investigations with short-term follow-up of potentially exposed persons and virologic confirmation of infections; second, studies conducted across epidemics typically evaluating rates of acute respiratory illness among persons with serologic evidence of infection, in some cases adjusting for background rates of illness from other causes.
RESULTS
Most point estimates from studies of outbreak investigations fell in the range 4%-28% with low heterogeneity (I = 0%) with a pooled mean of 16% (95% confidence interval = 13%, 19%). Estimates from the studies conducted across epidemics without adjustment were very heterogeneous (point estimates 0%-100%; I = 97%), while estimates from studies that adjusted for background illnesses were more consistent with point estimates in the range 65%-85% and moderate heterogeneity (I = 58%). Variation in estimates could be partially explained by differences in study design and analysis, and inclusion of mild symptomatic illnesses as asymptomatic in some studies.
CONCLUSIONS
Estimates of the asymptomatic fraction are affected by the study design, and the definitions of infection and symptomatic illness. Considerable differences between the asymptomatic fraction of infections confirmed by virologic versus serologic testing may indicate fundamental differences in the interpretation of these two indicators.
Topics: Asymptomatic Infections; Disease Outbreaks; Epidemics; Humans; Influenza, Human
PubMed: 26133025
DOI: 10.1097/EDE.0000000000000340 -
BMJ Clinical Evidence Sep 2008Postoperative pulmonary infections are associated with cough, phlegm, shortness of breath, chest pain, temperature above 38 degrees C, and pulse rate above 100 a minute.... (Review)
Review
INTRODUCTION
Postoperative pulmonary infections are associated with cough, phlegm, shortness of breath, chest pain, temperature above 38 degrees C, and pulse rate above 100 a minute. Up to half of people may have asymptomatic chest signs after surgery, and up to a quarter develop symptomatic disease. The main risk factor is the type of surgery, with higher risks associated with surgery to the chest, abdomen, and head and neck compared with other operations. Other risk factors include age over 50 years, chronic obstructive pulmonary disease (COPD), smoking, hypoalbuminemia, and being functionally dependent.
METHODS AND OUTCOMES
We conducted a systematic review and aimed to answer the following clinical question: What are the effects of interventions to prevent postoperative pulmonary infections? We searched: Medline, Embase, The Cochrane Library, and other important databases up to May 2007 (BMJ Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).
RESULTS
We found 17 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.
CONCLUSIONS
In this systematic review we present information relating to the effectiveness and safety of the following interventions: advice to stop smoking preoperatively, anaesthesia, lung expansion techniques, and postoperative nasogastric decompression.
Topics: Abdomen; Humans; Lung Diseases; Postoperative Complications; Postoperative Period; Risk Factors; Smoking
PubMed: 19445796
DOI: No ID Found -
Travel Medicine and Infectious Disease 2021COVID-19 can be asymptomatic in a substantial proportion of patients. The assessment and management of these patients constitute a key element to stop dissemination.
BACKGROUND
COVID-19 can be asymptomatic in a substantial proportion of patients. The assessment and management of these patients constitute a key element to stop dissemination.
AIM
To describe the assessment and treatment of asymptomatic infection in patients with a confirmed diagnosis of COVID-19.
METHODS
We searched five databases and search engines for preprints/preproofs, up to August 22, 2020. We included cohort, cross-sectional, and case series studies, reporting the assessment and management of asymptomatic individuals. We extracted data on total discharges with negative PCR, length of hospitalization, treatment, and number of patients who remained asymptomatic. A random-effects model with inverse variance method was used to calculate the pooled prevalence.
RESULTS
41 studies (nine cross-sectional studies, five retrospective studies and 27 reports/case series; 647 asymptomatic individuals), were included, of which 47% were male (233/501). The age of patients was between 1month and 73 years. In patients who became symptomatic, length of hospitalization mean was 13.6 days (SD 6.4). Studies used lopinavir/ritonavir, hydroxychloroquine plus ritonavir/lopinavir, hydroxychloroquine with and without azithromycin, ribavirin plus interferon and interferon alfa. The proportion of individuals who remained asymptomatic was 91% (463/588 patients; 95%CI: 78.3%-98.7%); and asymptomatic individuals discharged with negative PCR was 86% (102/124 individuals; 95%CI: 58.4%-100%).
CONCLUSIONS
There is no standard treatment for asymptomatic COVID-19 individuals. There are no studies of adequate design to make this decision. It has been shown that most asymptomatic individuals who were followed have recovered, but this cannot be attributed to standard treatment.
Topics: Adolescent; Adult; Aged; Anti-Bacterial Agents; Antiviral Agents; Asymptomatic Infections; Azithromycin; COVID-19; COVID-19 Nucleic Acid Testing; Child; Child, Preschool; Drug Therapy, Combination; Female; Hospitalization; Humans; Hydroxychloroquine; Infant; Lopinavir; Male; Middle Aged; Reverse Transcriptase Polymerase Chain Reaction; Ritonavir; SARS-CoV-2; Young Adult; COVID-19 Drug Treatment
PubMed: 33838319
DOI: 10.1016/j.tmaid.2021.102058 -
PLoS Medicine May 2022Debate about the level of asymptomatic Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection continues. The amount of evidence is increasing and study... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Debate about the level of asymptomatic Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection continues. The amount of evidence is increasing and study designs have changed over time. We updated a living systematic review to address 3 questions: (1) Among people who become infected with SARS-CoV-2, what proportion does not experience symptoms at all during their infection? (2) What is the infectiousness of asymptomatic and presymptomatic, compared with symptomatic, SARS-CoV-2 infection? (3) What proportion of SARS-CoV-2 transmission in a population is accounted for by people who are asymptomatic or presymptomatic?
METHODS AND FINDINGS
The protocol was first published on 1 April 2020 and last updated on 18 June 2021. We searched PubMed, Embase, bioRxiv, and medRxiv, aggregated in a database of SARS-CoV-2 literature, most recently on 6 July 2021. Studies of people with PCR-diagnosed SARS-CoV-2, which documented symptom status at the beginning and end of follow-up, or mathematical modelling studies were included. Studies restricted to people already diagnosed, of single individuals or families, or without sufficient follow-up were excluded. One reviewer extracted data and a second verified the extraction, with disagreement resolved by discussion or a third reviewer. Risk of bias in empirical studies was assessed with a bespoke checklist and modelling studies with a published checklist. All data syntheses were done using random effects models. Review question (1): We included 130 studies. Heterogeneity was high so we did not estimate a mean proportion of asymptomatic infections overall (interquartile range (IQR) 14% to 50%, prediction interval 2% to 90%), or in 84 studies based on screening of defined populations (IQR 20% to 65%, prediction interval 4% to 94%). In 46 studies based on contact or outbreak investigations, the summary proportion asymptomatic was 19% (95% confidence interval (CI) 15% to 25%, prediction interval 2% to 70%). (2) The secondary attack rate in contacts of people with asymptomatic infection compared with symptomatic infection was 0.32 (95% CI 0.16 to 0.64, prediction interval 0.11 to 0.95, 8 studies). (3) In 13 modelling studies fit to data, the proportion of all SARS-CoV-2 transmission from presymptomatic individuals was higher than from asymptomatic individuals. Limitations of the evidence include high heterogeneity and high risks of selection and information bias in studies that were not designed to measure persistently asymptomatic infection, and limited information about variants of concern or in people who have been vaccinated.
CONCLUSIONS
Based on studies published up to July 2021, most SARS-CoV-2 infections were not persistently asymptomatic, and asymptomatic infections were less infectious than symptomatic infections. Summary estimates from meta-analysis may be misleading when variability between studies is extreme and prediction intervals should be presented. Future studies should determine the asymptomatic proportion of SARS-CoV-2 infections caused by variants of concern and in people with immunity following vaccination or previous infection. Without prospective longitudinal studies with methods that minimise selection and measurement biases, further updates with the study types included in this living systematic review are unlikely to be able to provide a reliable summary estimate of the proportion of asymptomatic infections caused by SARS-CoV-2.
REVIEW PROTOCOL
Open Science Framework (https://osf.io/9ewys/).
Topics: Asymptomatic Infections; COVID-19; Humans; Mass Screening; Prospective Studies; SARS-CoV-2
PubMed: 35617363
DOI: 10.1371/journal.pmed.1003987 -
BMC Infectious Diseases Sep 2023Although many studies on asymptomatic norovirus infection in outbreaks have been conducted globally, structured data (important for emergency management of outbreaks) on... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Although many studies on asymptomatic norovirus infection in outbreaks have been conducted globally, structured data (important for emergency management of outbreaks) on the prevalence of this epidemic are still not available. This study assessed the global prevalence of asymptomatic norovirus infection in outbreaks.
METHODS
We identified publications on asymptomatic infections from norovirus outbreaks by searching the PubMed, Embase, Cochrane Library, Medline, and Web of Science databases and screening references from the articles reviewed. Prevalence of asymptomatic norovirus infection in outbreaks was employed as the primary summary data. The random-effects model of the meta-analysis was fitted to generate estimates of the prevalence in the overall and subgroup populations.
RESULTS
In total, 44 articles with a sample size of 8,115 asymptomatic individuals were included. The estimated pooled prevalence of asymptomatic norovirus infection in outbreaks was 21.8% (95%CI, 17.4-27.3). The asymptomatic prevalence of norovirus GII (20.1%) was similar to that of GI (19.8%); however, the proportion prevalence of asymptomatic individuals involved in the former (33.36%) was significantly higher than that of in the latter (0.92%) and the former (93.18%) was reported much more frequently than the latter (15.91%) in the included articles. These studies had significant heterogeneity (I = 92%, τ = 0.4021, P < 0.01). However, the source of heterogeneity could not be identified even after subgroup analysis of 10 possible influencing factors (geographical area, outbreak settings, outbreak seasons, sample types, norovirus genotypes, transmission routes, subjects' occupations, subjects' age, per capita national income, and clear case definition). Meta-regression analysis of these 10 factors demonstrated that the geographical area could be partly responsible for this heterogeneity (P = 0.012).
CONCLUSIONS
The overall pooled asymptomatic prevalence of norovirus in outbreaks was high, with genome II dominating. Asymptomatic individuals may play an important role in norovirus outbreaks. This knowledge could help in developing control strategies and public health policies for norovirus outbreaks.
Topics: Humans; Asymptomatic Infections; Prevalence; Disease Outbreaks; Epidemics; Norovirus
PubMed: 37700223
DOI: 10.1186/s12879-023-08519-y -
Emerging Infectious Diseases Jun 2016Influenza infection manifests in a wide spectrum of severity, including symptomless pathogen carriers. We conducted a systematic review and meta-analysis of 55 studies... (Meta-Analysis)
Meta-Analysis Review
Influenza infection manifests in a wide spectrum of severity, including symptomless pathogen carriers. We conducted a systematic review and meta-analysis of 55 studies to elucidate the proportional representation of these asymptomatic infected persons. We observed extensive heterogeneity among these studies. The prevalence of asymptomatic carriage (total absence of symptoms) ranged from 5.2% to 35.5% and subclinical cases (illness that did not meet the criteria for acute respiratory or influenza-like illness) from 25.4% to 61.8%. Statistical analysis showed that the heterogeneity could not be explained by the type of influenza, the laboratory tests used to detect the virus, the year of the study, or the location of the study. Projections of infection spread and strategies for disease control require that we identify the proportional representation of these insidious spreaders early on in the emergence of new influenza subtypes or strains and track how this rate evolves over time and space.
Topics: Asymptomatic Infections; Humans; Influenza A virus; Influenza, Human; Population Surveillance; Prevalence; Publication Bias
PubMed: 27191967
DOI: 10.3201/eid2206.151080 -
The Cochrane Database of Systematic... Nov 2015Nasopharyngeal cancer is endemic in a few well-defined populations. The prognosis for advanced nasopharyngeal cancer is poor, but early-stage disease is curable and a... (Review)
Review
BACKGROUND
Nasopharyngeal cancer is endemic in a few well-defined populations. The prognosis for advanced nasopharyngeal cancer is poor, but early-stage disease is curable and a high survival rate can be achieved. Screening for early-stage disease could lead to improved outcomes. Epstein-Barr virus (EBV) serology and nasopharyngoscopy are most commonly used for screening. The efficacy and true benefit of screening remain uncertain due to potential selection, lead-time and length-time biases.
OBJECTIVES
To determine the effectiveness of screening of asymptomatic individuals by EBV serology and/or nasopharyngoscopy in reducing the mortality of nasopharyngeal cancer compared to no screening. To assess the impact of screening for nasopharyngeal cancer on incidence, survival, adverse effects, cost-effectiveness and quality of life.
SEARCH METHODS
The Cochrane Ear, Nose and Throat Disorders Group (CENTDG) Trials Search Co-ordinator searched the CENTDG Trials Register; Central Register of Controlled Trials (CENTRAL 2015, Issue 6); PubMed; EMBASE; CINAHL; Web of Science; Clinicaltrials.gov; ICTRP and additional sources for published and unpublished trials. The date of the search was 6 July 2015.
SELECTION CRITERIA
Randomised controlled trials (RCT) and controlled clinical trials (CCT) evaluating screening for nasopharyngeal cancer versus no screening. Randomisation either by clusters or individuals was acceptable.
DATA COLLECTION AND ANALYSIS
We used the standard methodological procedures expected by The Cochrane Collaboration. Our primary outcome measure was nasopharyngeal cancer-specific mortality. Secondary outcomes were incidence of nasopharyngeal cancer by stage and histopathological classification at diagnosis, survival (two-year, three-year, five-year and 10-year), harms of screening (physical and psychosocial), quality of life (via validated tools such as the SF-36 and patient satisfaction), cost-effectiveness and all-cause mortality.
MAIN RESULTS
We identified no trials that met the review inclusion criteria. We retrieved 31 full-text studies for further investigation following the search. However, none met the eligibility criteria for a RCT or CCT investigation on the efficacy of screening for nasopharyngeal cancer.
AUTHORS' CONCLUSIONS
No data from RCTs or CCTs are available to allow us to determine the efficacy of screening for nasopharyngeal cancer, or the cost-effectiveness and cost-benefit of a screening strategy. High-quality studies with long-term follow-up of mortality and cost-effectiveness are needed.
Topics: Asymptomatic Diseases; Carcinoma; Early Detection of Cancer; Endoscopy; Epstein-Barr Virus Infections; Herpesvirus 4, Human; Humans; Mass Screening; Nasopharyngeal Carcinoma; Nasopharyngeal Neoplasms
PubMed: 26544798
DOI: 10.1002/14651858.CD008423.pub2 -
International Journal of Environmental... Jan 2023Little is known about the long-term consequences of asymptomatic infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We aimed to review the... (Meta-Analysis)
Meta-Analysis Review
Little is known about the long-term consequences of asymptomatic infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We aimed to review the data available to explore the long-term consequences of asymptomatic SARS-CoV-2 infection in the real world. We searched observational cohort studies that described the long-term health effects of asymptomatic SARS-CoV-2 infections. Random-effects inverse-variance models were used to evaluate the pooled prevalence (PP) and its 95% confidence interval (CI) of long-term symptoms. Random effects were used to estimate the pooled odds ratios (OR) and its 95%CI of different long-term symptoms between symptomatic and asymptomatic infections. Five studies involving a total of 1643 cases, including 597 cases of asymptomatic and 1043 cases of symptomatic SARS-CoV-2 infection were included in this meta-analysis. The PPs of long-term consequences after asymptomatic SARS-CoV-2 infections were 17.13% (95%CI, 7.55−26.71%) for at least one symptom, 15.09% (95%CI, 5.46−24.73%) for loss of taste, 14.14% (95%CI, −1.32−29.61%) for loss of smell, and 9.33% (95%CI, 3.07−15.60) for fatigue. Compared with symptomatic SARS-CoV-2 infection, asymptomatic infection was associated with a significantly lower risk of developing COVID-19-related sequelae (p < 0.05), with 80% lower risk of developing at least one symptom (OR = 0.20, 95%CI, 0.09−0.45), 81% lower risk of fatigue (OR = 0.19, 95%CI, 0.08−0.49), 90% lower risk of loss of taste/smell (OR = 0.10, 95%CI, 0.02−0.58). Our results suggested that there were long-term effects of asymptomatic SARS-CoV-2 infection, such as loss of taste or smell, fatigue, cough and so on. However, the risk of developing long-term symptoms in asymptomatic SARS-CoV-2 infected persons was significantly lower than those in symptomatic SARS-CoV-2 infection cases.
Topics: Humans; COVID-19; SARS-CoV-2; Ageusia; Asymptomatic Infections; Fatigue
PubMed: 36674367
DOI: 10.3390/ijerph20021613