False-negative RT-PCR Results Research Articles

The Compatibility of Chest CT Scan with RT-PCR in Suspected COVID-19 Patients

Background: Thoracic CT scan plays a role in detecting and assessing the progression of COVID-19. It can evaluate the response to the therapy given. In diagnosis, the CT scan of the chest may complement the limitations of RT-PCR. Several recent studies have discussed the importance of CT scans in COVID-19 patients with false-negative RT-PCR results. The sensitivity of chest CT scan in the diagnosis of COVID-19 is reportedly around 98%. This study aimed to determine the compatibility of CT scan of the thorax with RT-PCR in suspected COVID-19 patients.
 Materials and methods: This research was conducted in the Radiology Department of the Wahidin Sudirohusodo Hospital Makassar from April to December 2020 with 350 patients. The method used was a 2x2 table diagnostic test.
 Results: The study included 188 male patients (53.7%) and 162 female patients (46.2%). The most common age group was 46–65 years (35.4%). The most common types of lesions were GGO (163 cases), consolidation (128 cases), and fibrosis (124 cases), mostly found in the inferior lobe with a predominantly peripheral or subpleural distribution. The sensitivity of the CT scan to the PCR examination was 86%, and the specificity was 91%.
 Conclusions: Thoracic CT scan was a good modality in establishing the diagnosis of COVID-19. CT scan of the chest with abnormalities could confirm the diagnosis in 88% of cases based on RT-PCR examination. It excluded the diagnosis in 91% based on the RT-PCR examination. The accuracy of the thoracic CT scan was 88% with RT-PCR as the reference value.

RT- PCR testing of upper respiratory tract samples for diagnosis of SARS-CoV-2: Between justification and overestimation, a multi-center international study

BackgroundIt has been found that patients recovered from COVID 19 may still test Reverse Transcriptase- Polymerase Chain Reaction (RT- PCR) positive without being infectious; the reasons are unclear. The occurrence of false-negative results of RT- PCR interferes with a proper diagnosis. The objectives of that work were to determine factors associated with persistently detectable SARS-CoV-2 RNA among recovered hospitalized patients and to determine the incidence of false-negative RT-PCR results and associated factors. MethodsRelevant data were collected from 482 COVID 19 patients hospitalized in six referral centers from four countries. ResultsThe median duration of RT- PCR conversion to negative was 20 days. Out of 482 studied patients, 8.7% tested positive after more than four weeks and were considered prolonged convertors. Binary logistic regression analysis revealed headache as an independent risk factor for short conversion time while fever, hypertension, chronic obstructive pulmonary disease, lymphopenia, elevated erythrocyte sedimentation rate, and the number of lobes affected, and bilateralism were found to be independent risk factors for prolonged positivity. Eighteen patients had initial negative results then turned positive after 24–48 h. Associated factors and outcomes were identified. ConclusionIdentifying patients with a high likelihood of COVID-19 despite a negative RT-PCR is critical for effective clinical care. However, patient isolation resumption depending on positive RT-PCR despite clinical and radiological recovery is an overrating that greatly burdens the health sector.

Meta-analysis of the robustness of COVID-19 diagnostic kit performance during the early pandemic

BackgroundAccurate detection of SARS-CoV-2 is necessary to mitigate the COVID-19 pandemic. However, the test reagents and assay platforms are varied and may not be sufficiently robust to diagnose COVID-19.MethodsWe reviewed...

Increasing False Negative RT-PCR Test in COVID-19 Patients Admitted at Tertiary Care Hospital: A Retrospective Cross-Sectional Study

Background: COVID-19 Pandemic has caused a lot of havoc for the human race, as the urgent need to detect the virus early and fight back stronger, scientists came up with the test RT-PCR, which later on was declared as the gold standard. But lately, an exponential increase in false-negative rates was observed, which calls for an accuracy check of the test and the statistical analysis of the reasons leading false-positive results. With the advent of the COVID-19 Pandemic, RT-PCR testing has become the gold standard for laboratory diagnosis of SARS-CoV-2 infection. But the second wave of COVID-19 in India has reported a high number of false-negative RT-PCR results. This calls for the need to measure the accuracy of the test in diagnosing infection, especially considering rise in variant strains each with its own virulence and infectivity. Imaging methods like HRCT and biochemical tests such as CRP, D-Dimer are being used increasingly by doctors to support the serological diagnostic method of Covid and draft further treatment protocols
 Objectives: To measure the false negative rates of RT-PCR in COVID-19 Patients. To find the epidemiology of the root cause.
 Methodology: For this Retrospective Cross-sectional study, sample size of 1998 with prevalence of 7894/million population and confidence interval of 95% we would be analysing patients of Datta Meghe Institute of Medical Sciences TCH admitted in the months of April to June 2021 with suspected COVID-19 Infection.
 Results: Increasing cases of false negative RT-PCR reports would be found.
 Conclusion: There is an urgent need for the reality check on efficacy of RT-PCR Test Reports.

Short-term outcomes of pregnant women with convalescent COVID-19 and factors associated with false-negative polymerase chain reaction test: A prospective cohort study.

AimTo evaluate the clinical factors associated with false‐negative RT‐PCR results and to report the outcome of a cohort of pregnant women with COVID‐19.MethodsThis cohort study was conducted in a tertiary referral pandemic hospital and included 56 pregnant women. A study including pregnant women with either a laboratory or clinical diagnosis for COVID‐19 were included in the study. The primary outcome was clinical factors associated with false‐negative RT‐PCR results defined as a positive immunoglobulin M assessed by rapid testing in clinically diagnosed patients. Clinical outcomes of laboratory diagnosed patients were also reported.ResultsIn total, 56 women with either RT‐PCR or clinical COVID‐19 diagnosis were included in the study. Forty‐three women either had RT‐PCR positivity or IgM positivity. The clinical outcome of these pregnancies was as follows: mean maternal age 27.7, immunoglobulin M positive patients 76.7%, RT‐PCR positive patients 55.8%, maternal comorbidities 11.5%, complications in patients below 20 weeks 34.8%, complications in patients above 20 weeks 65.1%, elevated CRP 83.7%, lymphopenia 30.2%, time from hospital admission to final follow‐up days 37 and stillbirth 8.3%. The proportion of women who tested positive for SARS‐CoV‐2 immunoglobulin M was 100% in the RT‐PCR positive group and 56.5% in the clinical diagnosis group (P = .002). The symptom onset to RT‐PCR testing interval longer than a week (risk ratio: 2.72, 95% CI: 1.14‐5.40, P = .003) and presence of dyspnoea (risk ratio: 0.38, 95% CI: 0.14‐0.89, P = .035) were associated with false‐negative RT‐PCR tests. The area under the curve of these parameters predicting false‐negative RT‐PCR was 0.73 (95% CI: 0.57‐0.89).ConclusionsSymptomatic women with a negative RT‐PCR should not be dismissed as potential COVID‐19 patients, especially in the presence of prolonged symptom onset‐test interval and in women without dyspnoea.

Estimate False-Negative RT-PCR Rates for SARS-CoV-2: A Systematic Review and Meta-Analysis

Molecular-based tests used to identify symptomatic or asymptomatic patients infected by SARS-CoV-2 are characterized by high specificity but scarce sensibility, generating false negative results with important implications for the correct identification of infected patients and subsequent repercussions on the entire community. We aimed to estimate, through a systematic review of the literature, the rate of RT-PCR false-negatives at initial testing for COVID-19. We systematically searched Pubmed, Embase, and CENTRAL as well as a list of reference literature. We included observational studies enrolling subject collected samples from respiratory tract to detect SARS-CoV-2 RNA using RT-PCR, reporting the number of false negative subjects and the number of final patients with a COVID-19 diagnosis. Reported rates of false negatives were pooled in a meta-analysis as appropriate. We assessed the risk of bias of included studies and graded the quality of evidence according to the GRADE method. All information in this article is current up to February 2021. We included 32 studies, enrolling more than 18,000 patients infected by SARS-CoV-2. The overall false negative rate was of 0.12 (95%CI from 0.10 to 0.14) with very low certainty of evidence. The impact of misdiagnoses was estimated according to disease prevalence; a range between 2 –58/1,000 subjects could be misdiagnosed with a disease prevalence of 10%,increasing to 290/1,000 misdiagnosed subjects with a disease prevalence of 50%. This systematic review showed that up to 58% of COVID-19 patients may have initial false-negative RT-PCR results, suggesting the need to implement a correct diagnostic strategy to correctly identify suspected cases, thereby reducing false negative results and decreasing the disease burden among the population.Funding: None to declare. Declaration of Interest: None to declare.

Algorithms for testing COVID-19 focused on use of RT-PCR and high-affinity serological testing: A consensus statement from a panel of Latin American experts

The COVID-19 pandemic has caused an unprecedented public health, social, and economic crisis. Improving understanding on available tests for detecting COVID-19 is critical for effective management of the pandemic. We proposed that a multidisciplinary expert panel can establish recommendations on ideal use of diagnostic tools, with a focus on RT-PCR and serological high-affinity antibodies (both IgM and IgG) tests for the Latin America region. Study designA collaborative multidisciplinary panel of 5 recognized experts in Latin America (an infectious disease specialist, three pathologists, and an immunologist) was convened and supported by Roche Diagnostics to develop standard guidelines and an evidence-based document of best practices on the use of diagnostic tools for COVID-19. ResultsThe authors reached consensus on the applicability of diagnostic tools to provide testing algorithms for the use of RT-PCR and serological high-affinity antibodies (both IgM and IgG) tests in three settings: 1) For asymptomatic subjects exposed to a SARS-CoV-2 infected person; 2) For epidemiological purposes and; 3) For symptomatic subjects. ConclusionThe serological high-affinity SARS-CoV-2 antibodies (both IgM and IgG) tests play a key role in COVID-19 diagnosis. These tests can be applied for suspected false-negative RT-PCR results and for individual determination of response. The use of these tests can also contribute greatly to public health strategies, such as population screening and supporting vaccination planning. Serological status for high-affinity antibodies (both IgM and IgG) should be performed ideally 21 days after potential infectious contact, given that the majority of exposed individuals will have seroconverted.

Clinical performance of four immunoassays for antibodies to SARS-CoV-2, including a prospective analysis for the diagnosis of COVID-19 in a real-life routine care setting.

The aim of the present study was to evaluate the clinical performance of four SARS-CoV-2 immunoassays and their contribution in routine care for the diagnosis of COVID-19, in order to benefit of robust data before their extensive use. The clinical performance of Euroimmun ELISA SARS-CoV-2 IgG, Abbott SARS-CoV-2 IgG, Wantai SARS-CoV-2 Ab ELISA, and DiaPro COVID-19 IgG confirmation were evaluated in the context of both a retrospective and a prospective analysis of COVID-19 patients. The retrospective analysis included plasma samples from 63 COVID-19 patients and 89 control (pre-pandemic) patients. The prospective study included 203 patients who tested either negative (n = 181) or positive (n = 22) by RT-PCR before serology sampling. The specificity was 92.1 %, 98.9 %, 100 % and 98.9 % and the sensitivity 14 days after onset of symptoms was 95.6 %, 95.6 %, 97.8 % and 95.6 % for Euroimmun IgG, Abbott IgG, Wantai Ab, and DiaPro IgG confirmation SARS-CoV-2 immunoassays, respectively. The low specificity of Euroimmun IgG (for ratio <5) was not confirmed in routine care setting (98.5 % negative agreement). Serology was complementary to RT-PCR in routine care and lead to identification of false positive (Ct>38, <2 targets detected) and false negative RT-PCR results (>1 month post onset of symptoms). Serology was complementary to RT-PCR for the diagnosis of COVID-19 at least 14 days after onset of symptoms. First line serology testing can be performed with Wantai Ab or Abbott IgG assays, while DiaPro IgG confirmation assay can be used as an efficient confirmation assay.

Antibody tests for identification of current and past infection with SARS-CoV-2.

Antibody tests for identification of current and past infection with SARS-CoV-2.

The usual course of thorax CT findings of COVID-19 infection and when to perform control thorax CT scan

COVID-19 infection, a highly contagious disease caused by the SARS-CoV virus, and the World Health Organization declared this increasingly spreading disease as a global public health emergency (pandemic). In the diagnosis of COVID-19, the polymerase chain reaction (RT-PCR) is considered as the reference standard test. In the early stages, thorax CT findings could be present even before the onset of symptoms, thorax CT has quite high sensitivity in COVID-19 patients with false negative RT-PCR results, and it has a great importance not only in diagnosis but also in follow up. We think that it might be beneficial for our radiologist colleagues in the early diagnosis of the imaging features of this disease, by sharing the experiences we have gained by evaluating the typical and relatively atypical CT findings regarding the natural course of the tomographic findings of COVID-19 and when to control CT.

Real-time reverse-transcription PCR in the diagnosis of influenza A (H1N1)v in intensive care unit adult patients

Regarding the interesting article on novel influenza A (H1N1)v infection in intensive care adult patients with severe respiratory failure recently published in Critical Care [1], we should like to make the following comments. The authors found that real-time RT-PCR for novel influenza A (H1N1)v virus in nasopharyngeal swabs on intensive care unit (ICU) admission was negative in four patients (12.5%) who later had a positive PCR result in respiratory secretions obtained at intubation, and concluded that 'a negative PCR result at admission should not exclude influenza A (H1N1)v due to the presence of false negative results in at least 10% cases' [1]. We of course understand what the authors meant. In our opinion, however, this assumption is formally inaccurate, and is somewhat misleading, as it might be inferred that real-time RT-PCR gives at least 10% of false negative results in patients with overt symptomatic influenza requiring ICU admission. The negative results reported by the authors cannot be considered true false negative RT-PCR results, as samples were not tested in parallel by a different assay yielding a positive result - in fact, RT-PCR, which was used at participating centers, is currently the standard method for the diagnosis of influenza. Optimal sensitivity of RT-PCR and rapid antigen tests is achieved when upper tract respiratory specimens are collected within the first few days after the onset of symptoms, as appeared to be the case for the above-mentioned patients. Inappropriate sampling or specimen processing or suboptimal sensitivity of the PCR assay used most probably accounted for the negative results. No speculation on this matter can be made because the microbiological information given to the readers was rather scarce. The possibility of false negative RT-PCR results for influenza A (H1N1)v in severely ill patients requiring admission to ICUs is a very important issue that must be further investigated.

Detection of four apple viruses by multiplex RT-PCR assays with coamplification of plant mRNA as internal control

Two multiplex RT-PCR assays with specific coamplification of plant mRNA as an internal control from total nucleic acids are described for the parallel detection of Apple chlorotic leaf spot virus, Apple stem pitting virus, Apple mosaic virus and Apple stem grooving virus. All are important economically and common pathogens in commercial apple and pear cultivars, except for Apple mosaic virus. Four virus specific primer pairs and one primer pair which allows the specific amplification of mRNA of the mitochondrial nad5 gene are described. Specificity of all primer pairs was confirmed by sequencing the RT-PCR products. A range of different virus isolates from various geographic origins could be detected by these multiplex RT-PCR assays all year round. Viruses were detected reliably in composite extracts at a ratio of one part total nucleic acid extract from an infected sample mixed with 39 parts of extract from healthy samples. The use of the internal control minimizes the risk of obtaining false negative RT-PCR results, which is desirable for routine testing, and avoids the need to eliminate contaminating DNA in extracts. To our knowledge, this is the first report on the use of a specific internal RNA control from total nucleic acids. The multiplex RT-PCR assays described are reliable, rapid and sensitive methods for the detection of these viruses, and may replace techniques need commonly like indexing by woody indicators or ELISA.