Asymptomatic SARS-CoV-2 infection: A systematic review and meta-analysis.
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ABSTRACT:
SUBMITTER: Sah P
PROVIDER: S-EPMC8403749 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description: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.
| S-EPMC9863678 | biostudies-literature
Project description: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.
| S-EPMC7855302 | biostudies-literature
Project description:PurposeThe short- and long-term andrological effects of coronavirus disease 2019 (COVID-19) have not been clarified. Our aim is to evaluate the available evidence regarding possible andrological consequences of COVID-19 either on seminal or hormonal parameters. The safety of the COVID-19 vaccines in terms of sperm quality was also investigated.MethodsAll prospective and retrospective observational studies reporting information on severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) mRNA semen and male genitalia tract detection (n = 19), as well as those reporting data on semen analysis (n = 5) and hormonal parameters (n = 11) in infected/recovered patients without any arbitrary restriction were included.ResultsOut of 204 retrieved articles, 35 were considered, including 2092 patients and 1138 controls with a mean age of 44.1 ± 12.6 years, and mean follow-up 24.3 ± 18.9 days. SARS-CoV-2 mRNA can be localized in male genitalia tracts during the acute phase of the disease. COVID-19 can result in short-term impaired sperm and T production. Available data cannot clarify long-term andrological effects. Low T observed in the acute phase of the disease is associated with an increased risk of being admitted to the Intensive Care Unit or death. The two available studies showed that the use of mRNA COVID-19 vaccines does not affect sperm quality.ConclusionsThe results of our analysis clearly suggest that each patient recovering from COVID-19 should be monitored to rule out sperm and T abnormalities. The specific contribution of reduced T levels during the acute phase of the infection needs to be better clarified.
| S-EPMC9080963 | biostudies-literature
Project description:BackgroundUnderstanding the level and characteristics of protection from past SARS-CoV-2 infection against subsequent re-infection, symptomatic COVID-19 disease, and severe disease is essential for predicting future potential disease burden, for designing policies that restrict travel or access to venues where there is a high risk of transmission, and for informing choices about when to receive vaccine doses. We aimed to systematically synthesise studies to estimate protection from past infection by variant, and where data allow, by time since infection.MethodsIn this systematic review and meta-analysis, we identified, reviewed, and extracted from the scientific literature retrospective and prospective cohort studies and test-negative case-control studies published from inception up to Sept 31, 2022, that estimated the reduction in risk of COVID-19 among individuals with a past SARS-CoV-2 infection in comparison to those without a previous infection. We meta-analysed the effectiveness of past infection by outcome (infection, symptomatic disease, and severe disease), variant, and time since infection. We ran a Bayesian meta-regression to estimate the pooled estimates of protection. Risk-of-bias assessment was evaluated using the National Institutes of Health quality-assessment tools. The systematic review was PRISMA compliant and was registered with PROSPERO (number CRD42022303850).FindingsWe identified a total of 65 studies from 19 different countries. Our meta-analyses showed that protection from past infection and any symptomatic disease was high for ancestral, alpha, beta, and delta variants, but was substantially lower for the omicron BA.1 variant. Pooled effectiveness against re-infection by the omicron BA.1 variant was 45·3% (95% uncertainty interval [UI] 17·3-76·1) and 44·0% (26·5-65·0) against omicron BA.1 symptomatic disease. Mean pooled effectiveness was greater than 78% against severe disease (hospitalisation and death) for all variants, including omicron BA.1. Protection from re-infection from ancestral, alpha, and delta variants declined over time but remained at 78·6% (49·8-93·6) at 40 weeks. Protection against re-infection by the omicron BA.1 variant declined more rapidly and was estimated at 36·1% (24·4-51·3) at 40 weeks. On the other hand, protection against severe disease remained high for all variants, with 90·2% (69·7-97·5) for ancestral, alpha, and delta variants, and 88·9% (84·7-90·9) for omicron BA.1 at 40 weeks.InterpretationProtection from past infection against re-infection from pre-omicron variants was very high and remained high even after 40 weeks. Protection was substantially lower for the omicron BA.1 variant and declined more rapidly over time than protection against previous variants. Protection from severe disease was high for all variants. The immunity conferred by past infection should be weighed alongside protection from vaccination when assessing future disease burden from COVID-19, providing guidance on when individuals should be vaccinated, and designing policies that mandate vaccination for workers or restrict access, on the basis of immune status, to settings where the risk of transmission is high, such as travel and high-occupancy indoor settings.FundingBill & Melinda Gates Foundation, J Stanton, T Gillespie, and J and E Nordstrom.
| S-EPMC9998097 | biostudies-literature
Project description:BackgroundAsymptomatic infections are potential sources of transmission for coronavirus disease 2019, especially during the epidemic of the SARS-CoV-2 Omicron variant. We aimed to assess the percentage of asymptomatic infections among SARS-CoV-2 Omicron variant-positive individuals detected by gene sequencing or specific polymerase chain reaction (PCR).MethodsWe searched PubMed, EMBASE, and Web of Science from 26 November 2021 to 13 April 2022. This meta-analysis was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and was registered with PROSPERO (CRD42022327894). Three researchers independently extracted data and two researchers assessed quality using pre-specified criteria. The pooled percentage with 95% confidence interval (CI) of asymptomatic infections of SARS-CoV-2 Omicron was estimated using random-effects models.ResultsOur meta-analysis included eight eligible studies, covering 7640 Omicron variant-positive individuals with 2190 asymptomatic infections. The pooled percentage of asymptomatic infections was 32.40% (95% CI: 25.30-39.51%) among SARS-CoV-2 Omicron variant-positive individuals, which was higher in the population in developing countries (38.93%; 95% CI: 19.75-58.11%), with vaccine coverage ≥ 80% (35.93%; 95% CI: 25.36-46.51%), with a travel history (40.05%; 95% CI: 7.59-72.51%), community infection (37.97%; 95% CI: 10.07-65.87%), and with a median age < 20 years (43.75%; 95% CI: 38.45-49.05%).ConclusionIn this systematic review and meta-analysis, the pooled percentage of asymptomatic infections was 32.40% among SARS-CoV-2 Omicron variant-positive individuals. The people who were vaccinated, young (median age < 20 years), had a travel history, and were infected outside of a clinical setting (community infection) had higher percentages of asymptomatic infections. Screening is required to prevent clustered epidemics or sustained community transmission caused by asymptomatic infections of Omicron variants, especially for countries and regions that have successfully controlled SARS-CoV-2.
| S-EPMC9321237 | biostudies-literature
Project description:Healthcare workers (HCWs) remain on the front line of the battle against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and coronavirus disease 2019 (COVID-19) infection and are among the highest groups at risk of infection during this raging pandemic. We conducted a systematic review and meta-analysis to assess the incidence of postvaccination SARS-CoV-2 infection among vaccinated HCWs. We searched multiple databases from inception through August 2021 to identify studies that reported on the incidence of postvaccination SARS-CoV-2 infection among HCWs. Meta-analysis was performed to determine pooled proportions of COVID-19 infection in partially/fully vaccinated as well as unvaccinated individuals. Eighteen studies with 228 873 HCWs were included in the final analysis. The total number of partially vaccinated, fully vaccinated, and unvaccinated HCWs were 132 922, 155 673, and 17 505, respectively. Overall pooled proportion of COVID-19 infections among partially/fully vaccinated and unvaccinated HCWs was 2.1% (95% confidence interval [CI] 1.2-3.5). Among partially vaccinated, fully vaccinated and unvaccinated HCWs, pooled proportion of COVID-19 infections was 2.3% (CI 1.2-4.4), 1.3% (95% CI 0.6-2.9), and 10.1% (95% CI 4.5-19.5), respectively. Our analysis shows the risk of COVID-19 infection in both partially and fully vaccinated HCWs remains exceedingly low when compared to unvaccinated individuals. There remains an urgent need for all frontline HCWs to be vaccinated against SARS-CoV-2 infection.
| S-EPMC8661690 | biostudies-literature
Project description:Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread rapidly throughout the world since the first cases of coronavirus disease 2019 (COVID-19) were observed in December 2019 in Wuhan, China. It has been suspected that infected persons who remain asymptomatic play a significant role in the ongoing pandemic, but their relative number and effect have been uncertain. The authors sought to review and synthesize the available evidence on asymptomatic SARS-CoV-2 infection. Asymptomatic persons seem to account for approximately 40% to 45% of SARS-CoV-2 infections, and they can transmit the virus to others for an extended period, perhaps longer than 14 days. Asymptomatic infection may be associated with subclinical lung abnormalities, as detected by computed tomography. Because of the high risk for silent spread by asymptomatic persons, it is imperative that testing programs include those without symptoms. To supplement conventional diagnostic testing, which is constrained by capacity, cost, and its one-off nature, innovative tactics for public health surveillance, such as crowdsourcing digital wearable data and monitoring sewage sludge, might be helpful.
| S-EPMC7281624 | biostudies-literature
Project description:BackgroundThere is disagreement about the level of asymptomatic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. We conducted a living systematic review and meta-analysis to address three questions: (1) Amongst people who become infected with SARS-CoV-2, what proportion does not experience symptoms at all during their infection? (2) Amongst people with SARS-CoV-2 infection who are asymptomatic when diagnosed, what proportion will develop symptoms later? (3) What proportion of SARS-CoV-2 transmission is accounted for by people who are either asymptomatic throughout infection or presymptomatic?Methods and findingsWe searched PubMed, Embase, bioRxiv, and medRxiv using a database of SARS-CoV-2 literature that is updated daily, on 25 March 2020, 20 April 2020, and 10 June 2020. Studies of people with SARS-CoV-2 diagnosed by reverse transcriptase PCR (RT-PCR) that documented follow-up and symptom status at the beginning and end of follow-up or modelling studies were included. 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 an adapted checklist for case series, and the relevance and credibility of modelling studies were assessed using a published checklist. We included a total of 94 studies. The overall estimate of the proportion of people who become infected with SARS-CoV-2 and remain asymptomatic throughout infection was 20% (95% confidence interval [CI] 17-25) with a prediction interval of 3%-67% in 79 studies that addressed this review question. There was some evidence that biases in the selection of participants influence the estimate. In seven studies of defined populations screened for SARS-CoV-2 and then followed, 31% (95% CI 26%-37%, prediction interval 24%-38%) remained asymptomatic. The proportion of people that is presymptomatic could not be summarised, owing to heterogeneity. The secondary attack rate was lower in contacts of people with asymptomatic infection than those with symptomatic infection (relative risk 0.35, 95% CI 0.10-1.27). Modelling studies fit to data found a higher proportion of all SARS-CoV-2 infections resulting from transmission from presymptomatic individuals than from asymptomatic individuals. Limitations of the review include that most included studies were not designed to estimate the proportion of asymptomatic SARS-CoV-2 infections and were at risk of selection biases; we did not consider the possible impact of false negative RT-PCR results, which would underestimate the proportion of asymptomatic infections; and the database does not include all sources.ConclusionsThe findings of this living systematic review suggest that most people who become infected with SARS-CoV-2 will not remain asymptomatic throughout the course of the infection. The contribution of presymptomatic and asymptomatic infections to overall SARS-CoV-2 transmission means that combination prevention measures, with enhanced hand hygiene, masks, testing tracing, and isolation strategies and social distancing, will continue to be needed.
| S-EPMC7508369 | biostudies-literature
Project description:SARS-CoV-2 Omicron variant seemed to cause milder disease compared to previous predominated variants. We aimed to conduct a meta-analysis to assess the pooled proportion of nonsevere disease and asymptomatic infection among COVID-19 patients infected with Omicron and Delta. We searched PubMed, Embase, Web of Science, and China National Knowledge Infrastructure (CNKI) databases. We included studies of SARS-CoV-2 Omicron infection from November 1, 2021, to April 18, 2022, and studies of Delta infection from October 1, 2020, to June 30, 2022. Studies without corresponding data, with less than 50 patients, or obviously biased concerning main outcome were excluded. Meta-analysis was performed in R 4.2.0 with the "meta" package. Subgroup analyses were conducted by study group and vaccination status. The pooled proportion of asymptomatic infection and nonsevere disease with Omicron were 25.5% (95% confidence interval [CI] 17.0%-38.2%) and 97.9% (95% CI 97.1%-98.7%), significantly higher than those of Delta with 8.4% (95% CI 4.4%-16.2%) and 91.4% (95% CI 87.0%-96.0%). During Omicron wave, children and adolescents had higher proportion of asymptomatic infection, SOTR and the elderly had lower proportion of nonsevere disease, vaccination of a booster dose contributed to higher proportion of both asymptomatic infection and nonsevere disease. This study estimates the pooled proportion of asymptomatic infection and nonsevere disease caused by SARS-CoV-2 Omicron compared to other predominant variants. The result has important implications for future policy making.
| S-EPMC9538850 | biostudies-literature
Project description:We conducted this meta-analysis to determine the proportion of co-infection with influenza viruses in SARS-CoV-2 positive patients and to investigate the severity of COVID-19 in these patients. We included studies with SARS-CoV-2 infection confirmed by qRT-PCR and influenza virus infection (A and/or B) by nucleic acid tests. The proportion of co-infection was compared between children and adults, and between critically ill or deceased patients compared to overall patients. Fifty-four articles were included. The overall proportion of co-infection was 0.7%, 95%CI = [0.4 - 1.3]. Most influenza co-infections were due to the influenza A virus (74.4%). The proportion of co-infection with influenza viruses among children (3.2%, 95% CI = [0.9 - 10.9]) was significantly higher than that in adult patients (0.3%, 95% CI = [0.1 - 1.2]), p-value <0.01. The proportion of co-infection with influenza viruses among critically ill patients tended to be higher than that in overall patients (2.2%, 95% CI = [0.3 - 22.4] versus 0.6%, 95% CI = [0.3 - 1.2], respectively, p-value = 0.22). Screening for pathogens in co-infection, particularly influenza viruses in patients infected with SARS-CoV-2, is necessary. This warrants close surveillance and investigation of the co-incidences and interactions of SARS-CoV-2 and other respiratory viruses, which is facilitated by the expansion of syndromic diagnosis approaches through the use of multiplex PCR assays.
| S-EPMC8349735 | biostudies-literature