ABSTRACT
Objectives Rapid and accurate severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) diagnostic tests are crucial for controlling the spread of infections in emergency settings. This study evaluated the diagnostic accuracy of a point-of-care (POC) test based on loop-mediated isothermal amplification (LAMP) that produces rapid results within 30 min. Methods We prospectively included adult patients (age >19 years) who were diagnosed with SARS-CoV-2 infection within the last 3 days and symptomatic patients who had visited the emergency room. Posterior nasopharyngeal (PNP) swabs and throat swabs collected by physicians were used to test the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), accuracy, and Cohen's Kappa coefficient (k) of the POC index and reference reverse transcription quantitative polymerase chain reaction (RT-qPCR) test devices. Results Of the 352 participants, 102 (29.0%) tested positive via the RT-PCR-based reference test device;the RT-LAMP-based POC test had a sensitivity of 70.6% and specificity of 98.0%, with 93.5% PPV, 89.1% NPV, 35.5% PLR, and 3.4% NLR. Cohen's k correlation of results from the two devices was 0.74. The cycle threshold value between the positive and negative POC test results differed (17.6 vs. 24.6, p < 0.001). Conclusions The RT-LAMP POC test in the emergency medical setting has a fair predictive value in high viral load cases in terms of infectivity.
ABSTRACT
Environmental surface testing was performed to search for evidence of severe acute respiratory coronavirus virus 2 (SARS-CoV-2) environmental contamination by an asymptomatic SARS-CoV-2 carrier with persistently high viral loads under isolation. No evidence of environmental contamination was found. Further studies are needed to measure environmental contamination by SARS-CoV-2 carriers and to determine reasonable isolation periods.
Subject(s)
Asymptomatic Infections , Betacoronavirus/isolation & purification , Clinical Laboratory Techniques , Coronavirus Infections/diagnosis , Fomites/virology , Pneumonia, Viral/diagnosis , Quarantine/methods , Viral Load , Adult , COVID-19 , COVID-19 Testing , Child , Coronavirus Infections/prevention & control , Coronavirus Infections/transmission , Coronavirus Infections/virology , Female , Humans , Pandemics/prevention & control , Patients' Rooms , Pneumonia, Viral/prevention & control , Pneumonia, Viral/transmission , Pneumonia, Viral/virology , Quarantine/standards , SARS-CoV-2Subject(s)
COVID-19/diagnosis , Q Fever/diagnosis , Adult , Antibodies, Bacterial/blood , Antibodies, Viral/blood , COVID-19/virology , Coinfection/diagnosis , Coxiella burnetii/isolation & purification , Enzyme-Linked Immunosorbent Assay , Humans , Immunoglobulin G/blood , Male , Oropharynx/virology , Q Fever/microbiology , SARS-CoV-2/genetics , SARS-CoV-2/isolation & purificationABSTRACT
On-site severe acute respiratory syndrome coronavirus 2 (SARS CoV-2) serological assays allow for timely in-field decisions to be made regarding patient status, also enabling population-wide screening to assist in controlling the coronavirus disease 2019 (COVID-19) pandemic. Here we propose a rapid microfluidic serological assay with two unique functions of nanointerstice filling and digitized flow control, which enable the fast/robust filling of the sample fluid as well as precise regulation of duration and volume of immune reaction. Developed microfluidic assay showed enhanced limit of detection, and 91.67% sensitivity and 100% specificity (n = 152) for clinical samples of SARS CoV-2 patients. The assay enables daily monitoring of IgM/IgG titers and patterns, which could be crucial parameters for convalescence from COVID-19 and provide important insight into how the immune system responds to SARS CoV-2. The developed on-site microfluidic assay presented the mean time for IgM and IgG seroconversions, indicating that these titers plateaued days after seroconversion. The mean duration from day 0 to PCR negativity was 19.4 days (median 20 d, IQR 16-21 d), with higher IgM/IgG titres being observed when PCR positive turns into negative. Simple monitoring of these titres promotes rapid on-site detection and comprehensive understanding of the immune response of COVID-19 patients.
Subject(s)
Biosensing Techniques , COVID-19 , Antibodies, Viral , Humans , Immunoassay , Immunoglobulin G , Immunoglobulin M , SARS-CoV-2 , Sensitivity and Specificity , Serologic TestsABSTRACT
To compare the standardized severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) seroprevalence of high epicenter region with non-epicenter region, serological studies were performed with a total of 3,268 sera from Daegu City and 3,981 sera from Chungbuk Province. Indirect immunofluorescence assay (IFA) for SARS-CoV-2 IgG results showed a high seroprevalence rate in the Daegu City (epicenter) compared with a non-epicenter area (Chungbuk Province) (1.27% vs. 0.91%, P = 0.0358). It is noteworthy that the highest seroprevalence in Daegu City was found in elderly patients (70's) whereas young adult patients (20's) in Chungbuk Province showed the highest seroprevalence. Neutralizing antibody (NAb) titers were found in three samples from Daegu City (3/3, 268, 0.09%) while none of the samples from Chungbuk Province were NAb positive. These results demonstrated that even following the large outbreak, the seropositive rate of SARS-CoV-2 in the general population remained low in South Korea.