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Background: Since the inception of the Coronavirus Disease-2019 (COVID-19) pandemic caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARSCoV-2) several methods were developed to identify and diagnose the disease such as rapid Polymerase Chain Reaction (PCR) test, rapid antibody test, and rapid antigen test. In Iraq, no study had evaluated the accuracy of the rapid antibody test before introducing it into the field. Objective: To assess the validity of the rapid test (Dutch-made Biozek) used in Iraq through calculating the sensitivity, specificity, positive and negative predictive values on a sample of suspected COVID-19 cases. Materials and Methods: A descriptive cross-sectional study conducted at two Primary Healthcare Centers (PHCs); 1000 individuals were included either because of the classical symptom of the disease and attended the PHC for testing or they were healthy individuals with close contact with a confirmed case at home or work. A structured questionnaire was filled in through direct interviews with the participants. Both rapid antibody test and PCR test were done simultaneously. The sensitivity, specificity, positive and negative predictive values were calculated. Results: Around 85% aged 20-60 years with almost equal gender distribution. About 78% were symptomatic, and 32.6% had history of contact with a confirmed case. The sensitivity was 14% for Immunoglobin (Ig) G, 3.2% for IgM and 5.7% for both, compared to specificity which was 74.5% for IgG, 95.1% for IgM and 91.3% for both. While the Positive Predictive Value (PPV) was 32.8% for IgG, 36.6% for IgM, and 37% for both, and the Negative Predictive Value (NPV) was 49.3% for IgG, 52.5% for IgM and 52.1% for both. Conclusion: Rapid antibody test used in this study which is not generally recommended for the early diagnosis of COVID-19 patients or in the screening programs. However, it can be used for epidemiological surveys purposes. [ABSTRACT FROM AUTHOR]

The extent of the SARS-CoV-2 circulation and the COVID-19 epidemic in Tunisia three months after virus circulation was unknown. The aim of this study was to determine the extent of SARS-CoV-2 infection among household contacts of confirmed COVID-19 cases living in Hot spot areas of Great Tunis, Tunisia by estimating the seroprevalence of antibodies anti SARS-CoV-2 and to identify factors associated to seroprevalence at the first stage of the pandemic in order to guide decision making and to constitute a baseline for further longitudinal analysis of protective immunity to SARS-CoV-2. The National Observatory of New and Emerging Diseases (ONMNE), Ministry of Health Tunisia (MoH), with the support of the Office of the World Health Organization Representative in Tunisia and the WHO Regional Office for the Eastern Mediterranean (EMRO)), conducted a household cross-sectional survey on April 2020 in Great Tunis (Tunis, Ariana, Manouba and Ben Arous). The study was based on the WHO seroepidemiological investigation protocol for SARS-CoV-2 infection. SARS-CoV-2 specific antibodies (IgG and IgM) were qualitatively detected using a lateral immunoassay that detect SARS-CoV-2 nucleocapsid protein and administered by the interviewers. The included subjects were confirmed COVID-19 cases and their households contacts resided in hot spot areas (cumulative incidence rate ≥ 10 cases/100,000 inhabitants) of Great Tunis. Results: In total, 1165 subjects were enrolled: 116 confirmed COVID-19 cases (43 active cases and 73 convalescents cases) and 1049 household contacts resided in 291 households. The median age of participants was 39.0 with 31 years’ interquartile range (Min = 8 months; Max = 96 years). The sex ratio (M/F) was 0.98. Twenty-nine per cent of participants resided in Tunis. The global crude seroprevalence among household contacts was 2.5% (26/1049); 95% CI 1.6–3.6%, 4.8%; 95% CI 2.3–8.7% in Ariana governorate and 0.3%; 95% CI 0.01%–1.8% in Manouba governorate. In multivariate analysis, the associated factors independently related to seroprevalence were age ≥25 years (aOR = 5.1; 95% CI 1.2–22.0), history of travel outside Tunisia since January 2020 (aOR = 4.6; 95% CI 1.7–12.9), symptomatic illness in the previous four months (aOR = 3.5; 95% CI 1.4–9.0) and governorate of residence (p = 0.02). The low seroprevalence estimated among household contacts in Great Tunis reflect the effect of public health measures early taken (national lockdown, borders closed, remote work), the respect of non-pharmaceutical interventions and the efficacy of COVID-19 contact-tracing and case management at the first stage of the pandemic in Tunisia.

Over the last three years, after the outbreak of the COVID-19 pandemic, an unprecedented number of novel diagnostic tests have been developed. Assays to evaluate the immune response to SARS-CoV-2 have been widely considered as part of the control strategy. The lateral flow immunoassay (LFIA), to detect both IgM and IgG against SARS-CoV-2, has been widely studied as a point-of-care (POC) test. Compared to laboratory tests, LFIAs are faster, cheaper and user-friendly, thus available also in areas with low economic resources. Soon after the onset of the pandemic, numerous kits for rapid antibody detection were put on the market with an emergency use authorization. However, since then, scientists have tried to better define the accuracy of these tests and their usefulness in different contexts. In fact, while during the first phase of the pandemic LFIAs for antibody detection were auxiliary to molecular tests for the diagnosis of COVID-19, successively these tests became a tool of seroprevalence surveillance to address infection control policies. When in 2021 a massive vaccination campaign was implemented worldwide, the interest in LFIA reemerged due to the need to establish the extent and the longevity of immunization in the vaccinated population and to establish priorities to guide health policies in low-income countries with limited access to vaccines. Here, we summarize the accuracy, the advantages and limits of LFIAs as POC tests for antibody detection, highlighting the efforts that have been made to improve this technology over the last few years.

The extent of the SARS-CoV-2 circulation and the COVID-19 epidemic in Tunisia three months after virus circulation was unknown. The aim of this study was to determine the extent of SARS-CoV-2 infection among household contacts of confirmed COVID-19 cases living in Hot spot areas of Great Tunis, Tunisia by estimating the seroprevalence of antibodies anti SARS-CoV-2 and to identify factors associated to seroprevalence at the first stage of the pandemic in order to guide decision making and to constitute a baseline for further longitudinal analysis of protective immunity to SARS-CoV-2. The National Observatory of New and Emerging Diseases (ONMNE), Ministry of Health Tunisia (MoH), with the support of the Office of the World Health Organization Representative in Tunisia and the WHO Regional Office for the Eastern Mediterranean (EMRO)), conducted a household cross-sectional survey on April 2020 in Great Tunis (Tunis, Ariana, Manouba and Ben Arous). The study was based on the WHO seroepidemiological investigation protocol for SARS-CoV-2 infection. SARS-CoV-2 specific antibodies (IgG and IgM) were qualitatively detected using a lateral immunoassay that detect SARS-CoV-2 nucleocapsid protein and administered by the interviewers. The included subjects were confirmed COVID-19 cases and their households contacts resided in hot spot areas (cumulative incidence rate ≥ 10 cases/100,000 inhabitants) of Great Tunis. Results: In total, 1165 subjects were enrolled: 116 confirmed COVID-19 cases (43 active cases and 73 convalescents cases) and 1049 household contacts resided in 291 households. The median age of participants was 39.0 with 31 years' interquartile range (Min = 8 months; Max = 96 years). The sex ratio (M/F) was 0.98. Twenty-nine per cent of participants resided in Tunis. The global crude seroprevalence among household contacts was 2.5% (26/1049); 95% CI 1.6–3.6%, 4.8%; 95% CI 2.3–8.7% in Ariana governorate and 0.3%; 95% CI 0.01%–1.8% in Manouba governorate. In multivariate analysis, the associated factors independently related to seroprevalence were age ≥25 years (aOR = 5.1; 95% CI 1.2–22.0), history of travel outside Tunisia since January 2020 (aOR = 4.6; 95% CI 1.7–12.9), symptomatic illness in the previous four months (aOR = 3.5; 95% CI 1.4–9.0) and governorate of residence (p = 0.02). The low seroprevalence estimated among household contacts in Great Tunis reflect the effect of public health measures early taken (national lockdown, borders closed, remote work), the respect of non-pharmaceutical interventions and the efficacy of COVID-19 contact-tracing and case management at the first stage of the pandemic in Tunisia. [ABSTRACT FROM AUTHOR]

Over the last three years, after the outbreak of the COVID-19 pandemic, an unprecedented number of novel diagnostic tests have been developed. Assays to evaluate the immune response to SARS-CoV-2 have been widely considered as part of the control strategy. The lateral flow immunoassay (LFIA), to detect both IgM and IgG against SARS-CoV-2, has been widely studied as a point-of-care (POC) test. Compared to laboratory tests, LFIAs are faster, cheaper and user-friendly, thus available also in areas with low economic resources. Soon after the onset of the pandemic, numerous kits for rapid antibody detection were put on the market with an emergency use authorization. However, since then, scientists have tried to better define the accuracy of these tests and their usefulness in different contexts. In fact, while during the first phase of the pandemic LFIAs for antibody detection were auxiliary to molecular tests for the diagnosis of COVID-19, successively these tests became a tool of seroprevalence surveillance to address infection control policies. When in 2021 a massive vaccination campaign was implemented worldwide, the interest in LFIA reemerged due to the need to establish the extent and the longevity of immunization in the vaccinated population and to establish priorities to guide health policies in low-income countries with limited access to vaccines. Here, we summarize the accuracy, the advantages and limits of LFIAs as POC tests for antibody detection, highlighting the efforts that have been made to improve this technology over the last few years. [ABSTRACT FROM AUTHOR]

Initial diagnosis of human T cell lymphotropic virus (HTLV) infections is mainly based by detecting antibodies in plasma or serum using laboratory-based methods. The aim of this study was to develop and evaluate a rapid screening test for HTLV-I antibodies. Our rapid screening test uses HTLV-I p24 antigen conjugated to gold nanoparticles and an anti-human IgG antibody immobilized to a nitrocellulose strip to detect human HTLV-I p24-specific IgG antibodies via immunochromatography. Performance of the rapid screening test for HTLV-I was conducted on a total of 118 serum specimens collected in Salvador, Bahia, the epicenter for HTLV-1 infection in Brazil. Using a Western blot test as the comparator, 55 serum specimens were HTLV-I positive, 5 were HTLV-I and HTLV-II positive, and 58 were negative. The sensitivity of the rapid screening test for HTLV-1 was 96.7% and the specificity was 100%. The rapid screening test did not show cross-reaction with serum specimens from individuals with potentially interfering infections including those caused by HTLV-II, HIV-I, HIV-II, hepatitis A virus, hepatitis B virus, hepatitis C virus, herpes simplex virus, Epstein–Barr virus, SARS-CoV-2, Chlamydia trachomatis, Neisseria gonorrhoeae, Treponema pallidum, Toxoplasma gondii, and Plasmodium falciparum. The rapid screening test also did not show cross-reaction with potentially interfering substances. Strategies for HTLV diagnosis in non- and high-endemic areas can be improved with low-cost, rapid screening tests. [ABSTRACT FROM AUTHOR]

Since March 2020, Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) infection has been around in Indonesia with a case fatality rate was 4.7% on August, 1th 2020. So far, the Real-Time Polymerase Chain Reaction (RT-PCR) method is the gold standard for the SARS-CoV-2 infection diagnosis. This method, however, has some limitations where it has a long turnaround time, complicated operations, and high prices. Hence, the rapid test kits are now readily available to identify the SARS-CoV-2 patients. The purpose of this study is to measure the diagnostic performance, including sensitivity, specificity, positive and negative predictive value, likelihood ratio or LR of antibody rapid test if compared with RT-PCR for the SARS-CoV-2 suspected patients in Bethesda Hospital Yogyakarta. This research was analytical observational research with a cross-sectional design approach, in which data were collected retrospectively. The instruments used in this study included e-medical record (ERM), Laboratory Information System (LIS) data from patients with suspected SARS-CoV-2 infection in Bethesda Hospital Yogyakarta. We collected demographic data of patients, RT-PCR results, antibody rapid test results using Standard Q COVID-19 IgM/IgG Combo. The data were obtained from 50 patients. The results showed that the Rapid test kit has a 100% sensitivity value, 74.4% specificity value, 38.9% positive and 100% negative predictive value, 3906 positive likelihood ratio compared with the RT-PCR results.

Introduction: Assessing patient history is solely insufficient to identify the asymptomatic Covid-19 cases in pregnancy. Therefore, regular laboratory examinations should be deemed to find the actual case. However, this strategy might be more challenging for a limited-resource area. Hence, finding the most effective laboratory screening is beneficial. This study aimed to collate the effectiveness of rapid antibody and universal reverse transcriptase-polymerase chain reaction (RT-PCR) for asymptomatic Covid-19 testing among pregnant women in low-resource settings. Methods: We performed a study using one-year retrospective data of asymptomatic Covid-19 cases among pregnant women admitted in Dr. Soetomo General Academic Hospital Surabaya, conducted with the paired rapid antibody test and RT-PCR SARS-CoV-2 result. Results: Of 265 cases included, 217 samples had a reactive rapid antibody test (81.89%). There was a significant association between rapid antibody test and RT-PCR (p=0.026) with sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were 89%, 22%, 38%, and 79%, respectively. Thus, it can identify more asymptomatic cases compared to identification by history and symptoms only. This study also revealed a higher significant efficiency cost (p<0.001) by reducing the overall expense up to IDR 36,180,000 (USD 2,514) or 15% lower than the universal RT-PCR SARS-CoV-2 testing strategy. Conclusion: This study suggests that implementing a rapid antibody test has favour in identifying more asymptomatic Covid-19 cases in pregnancy and evince more cost-effective than universal PCR testing. [ABSTRACT FROM AUTHOR]

Objectives: Due to the number of asymptomatic infections and limited access to high-performance antibody tests, the true prevalence and seropositivity of SARS-CoV-2 infection remains unknown. To fill this gap, the clinical performance of a point-of-care SARS-CoV-2 Rapid Antibody Assay, a chromatographic immunoassay for detecting IgM/IgG antibodies, in near patient settings was assessed. Methods: Forty-two anti-SARS-Cov-2 positive (CoV+) and 92 anti-SARS-Cov-2 negative (CoV–) leftover samples from before December 2019 were assessed; the Elecsys® Anti-SARS-CoV-2 was used as the reference assay. Analytical specificity was tested using leftover samples collected before December 2019 from patients with common cold symptoms. Results: The SARS-CoV-2 Rapid Antibody Test was 100.0% (95% CI 91.59–100.0) sensitive and 96.74% (95% CI 90.77–99.32) specific, with 0.00% assay failure rate. No cross-reactivity was observed against the common cold panel. Method comparison was additionally conducted by two external laboratories, using 100 CoV+ and 275 CoV– samples, also comparing whole blood versus plasma matrix. The comparison demonstrated 96.00% positive and 96.36% negative percent agreement for plasma with the Elecsys Anti-SARS-CoV-2 and 99.20% percent overall agreement between whole blood and EDTA plasma. Conclusion: The SARS-CoV-2 Rapid Antibody Test demonstrated similar performance to the manufacturer’s data and a centralised automated immunoassay, with no cross-reactivity with common cold panels.

• Timely, cost-effective determination of SARS-CoV-2 Ab could help pandemic migration. • iRapid self-test and professional measure neutralizing Ab in a semi-quantitative scale. • Both iRapid had good overall agreements of 95.1% and 95.9% for detecting minimum protection thresholds. • iRapid performances differ on the basis of the comparative reference assay. Performance of two disposable devices for identifying subjects with low anti-SARS-CoV-2 protection was compared with that of automated enzyme-linked immunosorbent (ELISA) and chemiluminescent (CLIA) assay. In July 2021, 123 healthcare workers (HCW), twice vaccinated by BNT162b2/Comirnaty mRNA (BioNTech-Pfizer), underwent Ab iRapid COVID-19 Quant "Neutralizing" Self - test (iRapid Self-test) and "Neutralizing" Professional-use (iRapid pro) (DIESSE, Diagnostica Senese, Siena, Italy). Simultaneously, serum Ab were determined by Maglumi 2000 plus (anti S-RBD CLIA assay, Snibe Diagnostics, Shenzhen, China) and SARS-CoV-2 "Neutralizing" Ab Chorus ELISA (DIESSE, Siena, Italy). Results were evaluated against two "protective-thresholds", 90 kBAU/L and 506 kBAU/L. HCW mean age, 46.2 (±12.6) years; 26 (20.5%), males, 101 (79.5%), females. The mean time interval (and standard deviation) between the first vaccine dose and Ab determination was 129.5 (±36.4) days and was neither gender (p = 0.879) nor age (p = 0.341) related. With Maglumi, 114 (89.7%) and 43 (33.8%) HCW presented Ab ≥ 90 kBAU/L and Ab ≥ 506 kBAU/L, respectively; with Chorus, 96 (75.6%) presented Ab values ≥506 kBAU/L. CLIA and ELISA agreement was 56.7%. At 90 kBAU/L, iRapid self-test and Pro sensitivities were 98.2% (95% CI: 92.7–99.8), specificity 69.2% (95% CI: 38.6–90.9%) and 76.9% (46.2–95%), respectively. At 506 kBAU/L, iRapid sensitivities were 58.1–91.6%, and specificities, 89–96.6%. On evaluating Ab at <4 and ≥4 months, protective titers had decreased. iRapid semi-quantitative devices had very good overall agreements of 95.1% and 95.9% for detecting individuals with low anti-SARS-CoV-2 protection. [ABSTRACT FROM AUTHOR]

Background and Objectives: The safety and effectiveness of vaccines are among the key priorities in COVID-19 pandemic management. Moreover, evidence-based data regarding vaccine safety and immunogenicity can play an important role in building the trust of the community regarding vaccination. The aim of this study was to investigate the safety and immunogenicity of Pfizer-BioNTech vaccine among healthcare workers in one hospital, 21 days after first dose. Materials and Methods: This study was conducted in the Hospital of the Lithuanian University of Health Sciences between February and March 2021. Hospital employees who arrived to receive the second dose of the Pfizer-BioNTech vaccine 21 days after the first one were invited to participate in the study: they were asked to complete an anonymous adverse events questionnaire and were offered a SARS-CoV-2 IgG/IgM rapid test. The study was performed at a single point, 21 days after the first dose of the vaccine. Results: Data of 4181 vaccine recipients were analysed. The first vaccine dose was associated with a 53.6% incidence of adverse events, mainly local reactions. Adverse events occurred more frequently in younger participants and women. Moderate adverse events were experienced by 1.4% of the vaccine recipients; 6.2% were incapacitated. Of the 3439 participants who performed a rapid IgG test, 94.5% were positive for IgG antibodies after the first vaccine dose. Seroconversion rates were lower in participants older than 47 years. Conclusions: Despite 1.4% moderate adverse events, no safety concerns or anaphylaxis were identified. The Pfizer-BioNTech vaccine induced an immune response in the overwhelming majority of recipients after a single dose. Younger participants experienced adverse events and were positive for IgG antibodies more frequently than older counterparts. It is important to mention that this study specifically considered short-term safety and reactions following vaccination and that long-term adverse effects were not investigated in the study. Thus, future research into both long-term adverse reactions and immune system programming is essential. [ABSTRACT FROM AUTHOR]

Objective:This study aims to assess the effectivity of a rapid antibody test on detecting the occupational exposure in healthcare professionals who have been working in a pandemic hospital since the initial cases were seen in our country.Methods:Prevention of Coronavirus disease 2019 (COVID-19) in our institution was managed according to the Republic of Turkey (T.C.) Ministry of Health recommendations. Between 20.04.2020 and 05.05.2020, 376 high-risk professionals (triage, emergency room, COVID-19 outpatient unit, COVID-19 clinic and intensive care unit) were screened by rapid antibody test for COVID-19. Positive cases were retrospectively examined in terms of COVID-19 diagnosis or potential symptoms of COVID-19 infection (fever, perspiration, debility, cough, myalgia, sour throat, nasal flow, diarrhea, loss of smell/taste sensation).Results:The mean age was 32.7±8.9 years, 222 patients were female and 154 were male. Positive rapid antibody test was detected in 27 (7.2%) patients: 24 of those had COVID-19 diagnosis or potential symptoms of COVID-19 infection, where 3 patients had no signs or symptoms of the disease.Conclusion:During pandemic, the reliability of rapid antibody tests has become under question due to validation issues. However, rapid antibody test may be feasible for COVID-19 screening among healthcare professionals in order to assess the precautions and prevent nosocomial infection.

• The rapid test for antibodies to SARS-COV-2 was 90.1% sensitive and 100% specific. • This is comparable to reference antibody tests for prior infection with COVID-19. • It could support clinical decision-making for patients with >10 days of symptoms. • It would be useful in settings where vaccination is not widespread. • And where PCR tests are not widely available. [ABSTRACT FROM AUTHOR]

Initial diagnosis of human T cell lymphotropic virus (HTLV) infections is mainly based by detecting antibodies in plasma or serum using laboratory-based methods. The aim of this study was to develop and evaluate a rapid screening test for HTLV-I antibodies. Our rapid screening test uses HTLV-I p24 antigen conjugated to gold nanoparticles and an anti-human IgG antibody immobilized to a nitrocellulose strip to detect human HTLV-I p24-specific IgG antibodies via immunochromatography. Performance of the rapid screening test for HTLV-I was conducted on a total of 118 serum specimens collected in Salvador, Bahia, the epicenter for HTLV-1 infection in Brazil. Using a Western blot test as the comparator, 55 serum specimens were HTLV-I positive, 5 were HTLV-I and HTLV-II positive, and 58 were negative. The sensitivity of the rapid screening test for HTLV-1 was 96.7% and the specificity was 100%. The rapid screening test did not show cross-reaction with serum specimens from individuals with potentially interfering infections including those caused by HTLV-II, HIV-I, HIV-II, hepatitis A virus, hepatitis B virus, hepatitis C virus, herpes simplex virus, Epstein–Barr virus, SARS-CoV-2, Chlamydia trachomatis, Neisseria gonorrhoeae, Treponema pallidum, Toxoplasma gondii, and Plasmodium falciparum. The rapid screening test also did not show cross-reaction with potentially interfering substances. Strategies for HTLV diagnosis in non- and high-endemic areas can be improved with low-cost, rapid screening tests.

Objective: We aimed to use SARS-CoV-2 antibody tests to assess the asymptomatic seroprevalence of individuals in high-risk hospital cohorts who's previous COVID-19 exposure is unknown; staff, and patients requiring haemodialysis or chemotherapy after the first wave.Methods: In a single Center, study participants had five SARS-CoV-2 antibody tests done simultaneously; one rapid diagnostic test (RDT) (Superbio Colloidal Gold IgM/IgG), and four laboratory tests (Roche Elecsys® Anti-SARS-CoV-2 IgG [RE], Abbott Architect i2000SR IgG [AAr], Abbott Alinity IgG [AAl], and Abbott Architect IgM CMIA). To determine seroprevalence, only positive test results on laboratory assay were considered true positives.Results: There were 157 participants, of whom 103 (65.6%) were female with a median age of 50 years (range 19–90). The IgG component of the RDT showed a high number of false positives (n = 18), was inferior to the laboratory assays (p < 0.001 RDT vs. AAl/AAr, p < 0.001 RDT vs. RE), and had reduced specificity (85.5% vs. AAl/AAr, 87.2% vs. RE). Sero-concordance was 97.5% between IgG laboratory assays (RE vs. AAl/AAr). Specificity of the IgM component of the RDT compared to Abbott IgM CMIA was 95.4%. Ten participants had positivity in at least one laboratory assay, seven (9.9%) of which were seen in HCWs. Two (4.1%) hematology/oncology (H/O) patients and a single (2.7%) haemodialysis (HD) were asymptomatically seropositive. Asymptomatic seroprevalence of HCWs compared to patients was not significant (p = 0.105).Conclusion: HCWs (9.9%) had higher, although non-significant asymptomatic seroprevalence of SARS-CoV-2 antibodies compared to high-risk patients (H/O 4.1%, HD 2.7%). An IgM/IgG rapid diagnostic test was inferior to laboratory assays. Sero-concordance of 97.5% was found between IgG laboratory assays, RE vs. AAl/AAr.

Background: The usability of laboratory tests related to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is critically important for the world undergoing the COVID-19 pandemic. The present study aimed to assess the diagnostic usability of rapid tests for the detection of antibody against SARS-CoV-2 through comparison of their results with the results of reverse transcription polymerase chain reaction (RT-PCR) test for the detection of SARS-CoV-2 genomic RNA and with the results of a quantitative test for antibody detection. Methods: Serum samples were collected from 18 patients undergoing RT-PCR testing for SARS-CoV-2. Twelve patients were RT-PCR positive while six were negative. A quantitative test based on chemiluminescent immunoassay and three rapid tests based on immunochromatography were performed to detect anti-SARS-CoV-2 IgG and IgM. Results: All the antibody tests exhibited poor sensitivity at the timing of initial RT-PCR diagnosis. IgG responses occurring prior to or simultaneously with IgM responses were observed through not only the quantitative test but also the three rapid tests. Based on concordance with the quantitative test results, the large variance among the three rapid tests was revealed. Conclusions: All antibody tests were unsatisfactory to replace RT-PCR for the early diagnosis of COVID-19. Rapid antibody tests as well as a quantitative antibody test were useful in the assessment of immune responses in COVID-19. The obvious variance among the three rapid tests suggested limited accuracy and difficult standardization. Diagnostic usability of rapid antibody tests for COVID-19 should be investigated rigorously. [ABSTRACT FROM AUTHOR]

The ongoing coronavirus disease 2019 (COVID‐19) epidemic has made a huge impact on health, economies, and societies all over the world. Although reverse transcription‐polymerase chain reaction (RT‐PCR)‐based nucleic acid detection has been primarily used in the diagnosis of COVID‐19, it is time‐consuming with limited application scenarios and must be operated by qualified personnel. Antibody test, particularly point‐of‐care antibody testing, is a suitable complement to nucleic acid test as it provides rapid, portable, and cost‐effective detection of infections. In this study, a Rapid Antibody Test Kit was developed based on fluorescence immunochromatography for the sensitive, accurate, and automated detection of immunoglobulin M (IgM) and IgG antibodies against severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) in human serum, plasma, and whole blood samples within 10 min. The sensitivity, specificity, precision, and stability of the test kit were of good performance. No cross‐activity and no interference was observed. In the multiple‐center parallel study, 223 samples from hospitalized patients were used to evaluate the clinical specificity of the test. Both SARS‐CoV‐2 IgM and IgG achieved a clinical specificity of 98.21%. The clinical sensitivities of SARS‐CoV‐2 IgM and IgG were 79.54% and 87.45%, respectively, among 733 reverse transcription‐polymerase chain reaction (RT‐PCR) confirmed SARS‐CoV‐2 samples. For the combined IgM and IgG assays, the sensitivity and specificity were 89.22% and 96.86%, respectively. Our results demonstrate that the combined use of IgM and IgG could serve as a more suitable alternative detection method for patients with COVID‐19, and the developed kit is of great public health significance for the prevention and control of the COVID‐19 pandemic. Highlights: We developed a rapid SARS‐CoV‐2 IgM and IgG test, which could be easy‐use and automatic for prevention and control of the COVID‐19 pandemic.The test showed good performance in evaluation of sensitivity, specificity, precision, and stability, and no cross‐activity and interference was observed.The combined use of IgM and IgG showed could be more suitable for COVID‐19 patients. [ABSTRACT FROM AUTHOR]

• The Rapid Antibody Test was 100% sensitive in detecting 42 of 42 SARS-CoV-2 positive samples. • The SARS-CoV-2 Rapid Antibody Test was 96.86% (155 of 159) specific at 10-minute readout time. • Cold-like-symptom samples had no cross-reactivity with the Rapid Antibody Test. Due to the number of asymptomatic infections and limited access to high-performance antibody tests, the true prevalence and seropositivity of SARS-CoV-2 infection remains unknown. To fill this gap, the clinical performance of a point-of-care SARS-CoV-2 Rapid Antibody Assay, a chromatographic immunoassay for detecting IgM/IgG antibodies, in near patient settings was assessed. Forty-two anti-SARS-Cov-2 positive (CoV+) and 92 anti-SARS-Cov-2 negative (CoV–) leftover samples from before December 2019 were assessed; the Elecsys® Anti-SARS-CoV-2 was used as the reference assay. Analytical specificity was tested using leftover samples collected before December 2019 from patients with common cold symptoms. The SARS-CoV-2 Rapid Antibody Test was 100.0% (95% CI 91.59–100.0) sensitive and 96.74% (95% CI 90.77–99.32) specific, with 0.00% assay failure rate. No cross-reactivity was observed against the common cold panel. Method comparison was additionally conducted by two external laboratories, using 100 CoV+ and 275 CoV– samples, also comparing whole blood versus plasma matrix. The comparison demonstrated 96.00% positive and 96.36% negative percent agreement for plasma with the Elecsys Anti-SARS-CoV-2 and 99.20% percent overall agreement between whole blood and EDTA plasma. The SARS-CoV-2 Rapid Antibody Test demonstrated similar performance to the manufacturer's data and a centralised automated immunoassay, with no cross-reactivity with common cold panels. [ABSTRACT FROM AUTHOR]

Background and Objectives: The safety and effectiveness of vaccines are among the key priorities in COVID-19 pandemic management. Moreover, evidence-based data regarding vaccine safety and immunogenicity can play an important role in building the trust of the community regarding vaccination. The aim of this study was to investigate the safety and immunogenicity of Pfizer-BioNTech vaccine among healthcare workers in one hospital, 21 days after first dose. Materials and Methods: This study was conducted in the Hospital of the Lithuanian University of Health Sciences between February and March 2021. Hospital employees who arrived to receive the second dose of the Pfizer-BioNTech vaccine 21 days after the first one were invited to participate in the study: they were asked to complete an anonymous adverse events questionnaire and were offered a SARS-CoV-2 IgG/IgM rapid test. The study was performed at a single point, 21 days after the first dose of the vaccine. Results: Data of 4181 vaccine recipients were analysed. The first vaccine dose was associated with a 53.6% incidence of adverse events, mainly local reactions. Adverse events occurred more frequently in younger participants and women. Moderate adverse events were experienced by 1.4% of the vaccine recipients; 6.2% were incapacitated. Of the 3439 participants who performed a rapid IgG test, 94.5% were positive for IgG antibodies after the first vaccine dose. Seroconversion rates were lower in participants older than 47 years. Conclusions: Despite 1.4% moderate adverse events, no safety concerns or anaphylaxis were identified. The Pfizer-BioNTech vaccine induced an immune response in the overwhelming majority of recipients after a single dose. Younger participants experienced adverse events and were positive for IgG antibodies more frequently than older counterparts. It is important to mention that this study specifically considered short-term safety and reactions following vaccination and that long-term adverse effects were not investigated in the study. Thus, future research into both long-term adverse reactions and immune system programming is essential.

Tests used to diagnose Coronavirus Disease-2019 (COVID-19) disease; Polymerase Chain Reaction (PCR) test, Rapid Antibody Test (RAT) and Thorax Computed Tomography (CT) in patients with appropriate history, clinical and laboratory. The sensitivity of these tests changes during the course of the disease and it is difficult to diagnose if the appropriate test is not selected at the appropriate time. PCR test was applied to 3 cases who applied to our hospital and had findings suggesting COVID-19 in CT, and all tests were negative. Afterwards, 3 cases diagnosed with RAT and COVID-19 were treated appropriately. These 3 cases showed that PCR test negativity is not an adequate criterion to rule out the disease. Even if the PCR test is negative in patients with appropriate history and clinic, RAT and / or CT should be performed considering the time elapsed since the onset of the patient's symptoms. [ABSTRACT FROM AUTHOR]

Objective: This study aims to assess the effectivity of a rapid antibody test on detecting the occupational exposure in healthcare professionals who have been working in a pandemic hospital since the initial cases were seen in our country. Methods: Prevention of Coronavirus disease 2019 (COVID-19) in our institution was managed according to the Republic of Turkey (T.C.) Ministry of Health recommendations. Between 20.04.2020 and 05.05.2020, 376 high-risk professionals (triage, emergency room, COVID-19 outpatient unit, COVID-19 clinic and intensive care unit) were screened by rapid antibody test for COVID-19. Positive cases were retrospectively examined in terms of COVID-19 diagnosis or potential symptoms of COVID-19 infection (fever, perspiration, debility, cough, myalgia, sour throat, nasal flow, diarrhea, loss of smell/taste sensation). Results: The mean age was 32.7±8.9 years, 222 patients were female and 154 were male. Positive rapid antibody test was detected in 27 (7.2%) patients: 24 of those had COVID-19 diagnosis or potential symptoms of COVID-19 infection, where 3 patients had no signs or symptoms of the disease. Conclusion: During pandemic, the reliability of rapid antibody tests has become under question due to validation issues. However, rapid antibody test may be feasible for COVID-19 screening among healthcare professionals in order to assess the precautions and prevent nosocomial infection. [ABSTRACT FROM AUTHOR]

Initial diagnosis of human T cell lymphotropic virus (HTLV) infections is mainly based by detecting antibodies in plasma or serum using laboratory-based methods. The aim of this study was to develop and evaluate a rapid screening test for HTLV-I antibodies. Our rapid screening test uses HTLV-I p24 antigen conjugated to gold nanoparticles and an anti-human IgG antibody immobilized to a nitrocellulose strip to detect human HTLV-I p24-specific IgG antibodies via immunochromatography. Performance of the rapid screening test for HTLV-I was conducted on a total of 118 serum specimens collected in Salvador, Bahia, the epicenter for HTLV-1 infection in Brazil. Using a Western blot test as the comparator, 55 serum specimens were HTLV-I positive, 5 were HTLV-I and HTLV-II positive, and 58 were negative. The sensitivity of the rapid screening test for HTLV-1 was 96.7% and the specificity was 100%. The rapid screening test did not show cross-reaction with serum specimens from individuals with potentially interfering infections including those caused by HTLV-II, HIV-I, HIV-II, hepatitis A virus, hepatitis B virus, hepatitis C virus, herpes simplex virus, Epstein-Barr virus, SARS-CoV-2, Chlamydia trachomatis , Neisseria gonorrhoeae , Treponema pallidum , Toxoplasma gondii , and Plasmodium falciparum . The rapid screening test also did not show cross-reaction with potentially interfering substances. Strategies for HTLV diagnosis in non- and high-endemic areas can be improved with low-cost, rapid screening tests.

Abstract: Background: Excluding HIV infection among infants and young children in resource-poor settings where nucleic acid amplification tests (NAAT) are not routinely available remains a considerable challenge. Objectives: To assess the performance of two rapid HIV antibody tests (RT) used alone and in parallel for excluding HIV infection among acutely ill infants and children <18 months in comparison to NAAT in a region where maternal HIV prevalence was approximately 7%. Study Design: Infants and children ≥2<18 months admitted to hospital with an acute febrile illness had two rapid antibody tests in parallel, with single and parallel results subsequently compared against NAAT. Results: HIV prevalence among 1602 enrolled infants was 3.4%. All 1526 infants with 2 negative RT were HIV negative by NAAT. All 46 infants with 2 positive RT were HIV positive by NAAT. The overall specificity of two rapid tests for excluding HIV infection was 99.5%. Sensitivity and specificity were ≥99% and >98%, respectively, across all age brackets ≥2<18 months. Overall sensitivity and specificity for a single RT was 98.2% and 99%, respectively, for Determine, and 85.5% and 99.6%, respectively, for Capillus. Conclusions: In a setting with a maternal HIV prevalence rate of <10%, a single negative RT had excellent specificity and two negative RT performed in parallel had a perfect negative predictive value for HIV infection among acutely ill patients <18 months of age. In this and similar settings, RT could assist with excluding HIV infection with much lower complexity and cost than NAAT. [Copyright &y& Elsevier]

Background: The prompt detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is important in the therapeutic management of infected patients. Rapid diagnostic tests are widely used for this purpose. This study aimed to evaluate the clinical performance of four SARS-CoV-2 immunoglobulin IgG/IgM rapid diagnostic tests in the detection of SARS-CoV-2., Methods: Nasopharyngeal and oropharyngeal swabs and/or sputum were collected from 30 patients infected with SARS-CoV-2 and 30 healthy volunteers. All specimens were tested using four SARS-CoV-2 IgG/IgM rapid diagnostic tests and real-time polymerase chain reaction. We assessed the clinical sensitivity and specificity of the tests., Results: The clinical sensitivity of FREND™, SsmarTest™, BIOCREDIT™, and IVDLAB™ was 96.67%, 100.00%, 100.00%, and 96.67%, respectively, compared to real-time polymerase chain reaction. The clinical specificity was 96.67%, 100.00%, 86.67%, and 96.67%, respectively., Conclusion: These findings could expedite the detection of SARS-CoV-2 and thus reduce the risk of further transmission of the virus., (© 2022 The Authors. Journal of Clinical Laboratory Analysis published by Wiley Periodicals LLC.)

Background: Although the detection of viral particles by reverse transcription polymerase chain reaction (RT-PCR) is the gold standard diagnostic test for coronavirus disease 2019 (COVID-19), the false-negative results constitute a big challenge., Aim: To examine a group of patients diagnosed and treated as possible COVID-19 pneumonia whose multiple nasopharyngeal swab samples were negative for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by RT-PCR but then serological immunoglobulin M/immunoglobulin G (IgM/IgG) antibody against SARS-CoV-2 were detected by rapid antibody test., Methods: Eighty possible COVID-19 patients who had at least two negative consecutive COVID-19 RT-PCR test and were subjected to serological rapid antibody test were evaluated in this study., Results: The specific serological total IgM/IgG antibody against SARS-CoV-2 was detected in twenty-two patients. The mean age of this patient group was 63.2± 13.1-years-old with a male/female ratio of 11/11. Cough was the most common symptom (90.9%). The most common presenting chest computed tomography findings were bilateral ground glass opacities (77.2%) and alveolar consolidations (50.1%). The mean duration of time from appearance of first symptoms to hospital admission, to hospital admission, to treatment duration and to serological positivity were 8.6 d, 11.2 d, 7.9 d, and 24 d, respectively. Compared with reference laboratory values, serologically positive patients have shown increased levels of acute phase reactants, such as C-reactive protein, ferritin, and procalcitonin and higher inflammatory markers, such as erythrocyte sedimentation rate, lactate dehydrogenase enzyme, and fibrin end-products, such as D-dimer. A left shift on white blood cell differential was observed with increased neutrophil counts and decreased lymphocytes., Conclusion: Our study demonstrated the feasibility of a COVID-19 diagnosis based on rapid antibody test in the cases of patients whose RT-PCR samples were negative. Detection of antibodies against SARS-CoV-2 with rapid antibody test should be included in the diagnostic algorithm in patients with possible COVID-19 pneumonia., Competing Interests: Conflict-of-interest statement: All authors have contributed significantly, and that all authors are in agreement with the content and honesty of the manuscript. All authors declare that they have no conflict of interest., (©The Author(s) 2021. Published by Baishideng Publishing Group Inc. All rights reserved.)

Objective: We aimed to use SARS-CoV-2 antibody tests to assess the asymptomatic seroprevalence of individuals in high-risk hospital cohorts who's previous COVID-19 exposure is unknown; staff, and patients requiring haemodialysis or chemotherapy after the first wave. Methods: In a single Center, study participants had five SARS-CoV-2 antibody tests done simultaneously; one rapid diagnostic test (RDT) (Superbio Colloidal Gold IgM/IgG), and four laboratory tests (Roche Elecsys® Anti-SARS-CoV-2 IgG [RE], Abbott Architect i2000SR IgG [AAr], Abbott Alinity IgG [AAl], and Abbott Architect IgM CMIA). To determine seroprevalence, only positive test results on laboratory assay were considered true positives. Results: There were 157 participants, of whom 103 (65.6%) were female with a median age of 50 years (range 19-90). The IgG component of the RDT showed a high number of false positives ( n = 18), was inferior to the laboratory assays ( p < 0.001 RDT vs. AAl/AAr, p < 0.001 RDT vs. RE), and had reduced specificity (85.5% vs. AAl/AAr, 87.2% vs. RE). Sero-concordance was 97.5% between IgG laboratory assays (RE vs. AAl/AAr). Specificity of the IgM component of the RDT compared to Abbott IgM CMIA was 95.4%. Ten participants had positivity in at least one laboratory assay, seven (9.9%) of which were seen in HCWs. Two (4.1%) hematology/oncology (H/O) patients and a single (2.7%) haemodialysis (HD) were asymptomatically seropositive. Asymptomatic seroprevalence of HCWs compared to patients was not significant ( p = 0.105). Conclusion: HCWs (9.9%) had higher, although non-significant asymptomatic seroprevalence of SARS-CoV-2 antibodies compared to high-risk patients (H/O 4.1%, HD 2.7%). An IgM/IgG rapid diagnostic test was inferior to laboratory assays. Sero-concordance of 97.5% was found between IgG laboratory assays, RE vs. AAl/AAr., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 O'Kelly, McLaughlin, O'Doherty, Carroll, Murray, Dilworth, Corkery, Cotter, McGinty, Muldoon, Cullen, Avramovic, Sheehan, Sadlier, Higgins, O'Gorman, Doran, Inzitari, Holden, O'Meara, Ennis and Lambert.)