Project description:Amidst the COVID-19 pandemic, clinicians have been plagued with dilemmas related to the uncertainty about diagnostic testing for the virus. It has become commonplace for a patient under investigation (PUI) to repeatedly test negative but have imaging findings that are consistent with COVID-19. This raises the question of when the treating team should entertain alternative diagnoses. We present such a case to help provide a framework for how to weigh repeatedly negative test results in clinical decision making when there is ongoing concern for COVID-19.
Project description:BackgroundCOVID-19 is a multi-system infection with emerging evidence-based antiviral and anti-inflammatory therapies to improve disease prognosis. However, a subset of patients with COVID-19 signs and symptoms have repeatedly negative RT-PCR tests, leading to treatment hesitancy. We used comparative serology early in the COVID-19 pandemic when background seroprevalence was low to estimate the likelihood of COVID-19 infection among RT-PCR negative patients with clinical signs and/or symptoms compatible with COVID-19.MethodsBetween April and October 2020, we conducted serologic testing of patients with (i) signs and symptoms of COVID-19 who were repeatedly negative by RT-PCR ('Probables'; N = 20), (ii) signs and symptoms of COVID-19 but with a potential alternative diagnosis ('Suspects'; N = 15), (iii) no signs and symptoms of COVID-19 ('Non-suspects'; N = 43), (iv) RT-PCR confirmed COVID-19 patients (N = 40), and (v) pre-pandemic samples (N = 55).ResultsProbables had similar seropositivity and levels of IgG and IgM antibodies as propensity-score matched RT-PCR confirmed COVID-19 patients (60.0% vs 80.0% for IgG, p-value = 0.13; 50.0% vs 72.5% for IgM, p-value = 0.10), but multi-fold higher seropositivity rates than Suspects and matched Non-suspects (60.0% vs 13.3% and 11.6% for IgG; 50.0% vs 0% and 4.7% for IgM respectively; p-values < 0.01). However, Probables were half as likely to receive COVID-19 treatment than the RT-PCR confirmed COVID-19 patients with similar disease severity.ConclusionsFindings from this study indicate a high likelihood of acute COVID-19 among RT-PCR negative with typical signs/symptoms, but a common omission of COVID-19 therapies among these patients. Clinically diagnosed COVID-19, independent of RT-PCR positivity, thus has a potential vital role in guiding treatment decisions.
Project description:BackgroundA false-negative case of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is defined as a person with suspected infection and an initial negative result by reverse transcription-polymerase chain reaction (RT-PCR) test, with a positive result on a subsequent test. False-negative cases have important implications for isolation and risk of transmission of infected people and for the management of coronavirus disease 2019 (COVID-19). We aimed to review and critically appraise evidence about the rate of RT-PCR false-negatives at initial testing for COVID-19.MethodsWe searched MEDLINE, EMBASE, LILACS, as well as COVID-19 repositories, including the EPPI-Centre living systematic map of evidence about COVID-19 and the Coronavirus Open Access Project living evidence database. Two authors independently screened and selected studies according to the eligibility criteria and collected data from the included studies. The risk of bias was assessed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. We calculated the proportion of false-negative test results using a multilevel mixed-effect logistic regression model. The certainty of the evidence about false-negative cases was rated using the GRADE approach for tests and strategies. All information in this article is current up to July 17, 2020.ResultsWe included 34 studies enrolling 12,057 COVID-19 confirmed cases. All studies were affected by several risks of bias and applicability concerns. The pooled estimate of false-negative proportion was highly affected by unexplained heterogeneity (tau-squared = 1.39; 90% prediction interval from 0.02 to 0.54). The certainty of the evidence was judged as very low due to the risk of bias, indirectness, and inconsistency issues.ConclusionsThere is substantial and largely unexplained heterogeneity in the proportion of false-negative RT-PCR results. The collected evidence has several limitations, including risk of bias issues, high heterogeneity, and concerns about its applicability. Nonetheless, our findings reinforce the need for repeated testing in patients with suspicion of SARS-Cov-2 infection given that up to 54% of COVID-19 patients may have an initial false-negative RT-PCR (very low certainty of evidence).Systematic review registrationProtocol available on the OSF website: https://tinyurl.com/vvbgqya.
Project description:Infection of mouse bone marrow Flts3L-derived dendritic cells (FL-DCs) with chimeric human T cell leukemia virus type 1 (HTLV-1) results in the upregulation as well as selective downregulation of various DC-specific genes.
Project description:Early case detection and isolation of infected individuals are critical to controlling coronavirus disease 2019 (COVID-19). Reverse transcription polymerase chain reaction (RT-PCR) is considered the gold standard for the diagnosis of severe acute respiratory syndrome coronavirus 2 infection, but false negatives do occur. We built a user-friendly online tool to estimate the probability of having COVID-19 with negative RT-PCR results and thus avoid preventable transmission.
Project description:Background:Prolonged nucleic acid conversion and false-negative real-time polymerase chain reaction (RT-PCR) results might occur in COVID-19 patients rather than infection recurrence. Presentation of cases:We reported four cases who had negative RT-PCR results, in addition to the last two consecutive negative results. Patient-1 had negative RT-PCR results twice (the 6th and 8th) from a total of 11 swabs. Patient-2 had negative RT-PCR results once (the 5th) from a total of 8 swabs. Patient-3 showed negative results of RT-PCR twice (the 4th and 6th) from a total of 11 swabs. Patient-4 had negative RT-PCR results twice (the 2nd and 10th) from a total of 14 swabs. Discussion:The fluctuating trend of our RT-PCR results in our cases might be due to insufficient viral material in the specimen, laboratory errors during sampling, restrictions on sample transportation, or mutations in the primary and probe target regions in the SARS-CoV-2 genome. Several factors might affect the occurrence of prolonged nucleic acid conversion, including older age, comorbidities, such as diabetes and hypertension, and impaired immune function. Conclusion:Here, we confirmed the occurrence of prolonged nucleic acid conversion and the possibility of false negative RT-PCR results in COVID-19 patients.
Project description:Worldwide, the infectivity and disease burden of the H1N1 pandemic were overestimated because of limited clinical experience concerning patient presentation and outcome of those infected with the novel H1N1 virus.This study aimed to compare the epidemiologic clinical data among H1N1 RT-PCR-positive and RT-PCR-negative pneumonic patients during the 2009-2010 pandemic in Mansoura University Hospitals, Egypt.A record-based, case-control study was conducted for 43 adult patients admitted to the chest department isolation unit with community-acquired pneumonia during the 2009-2010 H1N1 pandemic after reviewing of 198 suspected and confirmed H1N1 hospitalized cases. Of these patients, 20 cases were confirmed to be H1N1-positive using an RT-PCR detection technique. The remaining 23 patients were RT-PCR-negative. Demographic, clinical, laboratory and radiological data were collected and analyzed using spss version 11.A review of 198 hospital case records for revealed one main peak of H1N1 influenza during the last week of December 2009. Pneumonic patients who were H1N1-positive were more likely to present with sore throat (P = 0·005), dyspnea (P = 0·002), and gastrointestinal (GIT) complaints (vomiting and diarrhea P = 0·02) when compared to the H1N1-negative group. Also, complications were significantly more frequent (P = 0·01) in the H1N1-confirmed group than in the non-confirmed group. However, no significant differences were found between the groups regarding length of hospital stay, intensive care unit (ICU), and admission or mortality.Sore throat, dyspnea, and presence of GIT complaints increase the suspicion of H1N1 positivity in pneumonia acquired during an H1N1 pandemic. However, H1N1 did not worsen the disease burden of pneumonia.
Project description:There is a need for understanding and establishment of the most appropriate testing algorithm for COVID-19 diagnosis in asymptomatic high-risk groups. Here, we present a retrospective analysis of RT-PCR results obtained from 412 cases tested negative for coronavirus disease 2019 (COVID-19) by rapid antigen testing method. Among 178 (43.2%) asymptomatic individuals, 44.9% of the high risk contacts, 12.2% of police custody individuals, 22.22% of the pregnant women and 33.33% of individuals hospitalised for preoperative or other medical conditions showed RT-PCR positivity. Our results suggest a need for focussed and intensive (multi-modality) testing in groups at high risk for SARS-CoV-2 infection.
Project description:The current COVID-19 pandemic demands massive testing by Real-time RT-PCR (Reverse Transcription Polymerase Chain Reaction), which is considered the gold standard diagnostic test for the detection of the SARS-CoV-2 virus. However, the virus continues to evolve with mutations that lead to phenotypic alterations as higher transmissibility, pathogenicity or vaccine evasion. Another big issue are mutations in the annealing sites of primers and probes of RT-PCR diagnostic kits leading to false-negative results. Therefore, here we identify mutations in the N (Nucleocapsid) gene that affects the use of the GeneFinder COVID-19 Plus RealAmp Kit. We sequenced SARS-CoV-2 genomes from 17 positive samples with no N gene detection but with RDRP (RNA-dependent RNA polymerase) and E (Envelope) genes detection, and observed a set of three different mutations affecting the N detection: a deletion of 18 nucleotides (Del28877-28894), a substitution of GGG to AAC (28881-28883) and a frameshift mutation caused by deletion (Del28877-28878). The last one cause a deletion of six AAs (amino acids) located in the central intrinsic disorder region at protein level. We also found this mutation in 99 of the 14,346 sequenced samples by the Sao Paulo state Network for Pandemic Alert of Emerging SARS-CoV-2 variants, demonstrating the circulation of the mutation in Sao Paulo, Brazil. Continuous monitoring and characterization of mutations affecting the annealing sites of primers and probes by genomic surveillance programs are necessary to maintain the effectiveness of the diagnosis of COVID-19.