Longitudinal waning of mRNA vaccine-induced neutralizing antibodies against SARS-CoV-2 detected by an LFIA rapid test

While mRNA vaccines against SARS-CoV-2 were highly efficacious against severe illness and hospitalization, they seem to be less effective in preventing infection months after vaccination, especially with the Delta variant. Breakthrough infections might be due to higher infectivity of the variants, relaxed protective measures by the general public in “COVID-19 fatigue”, and/or waning immunity post-vaccination. Determining the neutralizing antibody levels in a longitudinal manner may address this issue, but technical complexity of classic assays precludes easy detection and quick answers. We developed a lateral flow immunoassay NeutraXpress™ (commercial name of the test kit by Antagen Diagnostics, Inc.), and tested fingertip blood samples of subjects receiving either Moderna or Pfizer vaccines at various time points. With this device, we confirmed the reported clinical findings that mRNA vaccine-induced neutralizing antibodies quickly wane after 3–6 months. Thus, using rapid tests to monitor neutralizing antibody status could help identify individuals at risk, prevent breakthrough infections and guide social behavior to curtail the spread of COVID-19. Statement of Significance. Mounting evidence suggests that mRNA vaccine-induced neutralizing antibody titres against SARS-CoV-2 wane in 3–6 months. Quick identification of fully vaccinated persons with high risk of breakthrough infections is key to control the COVID-19 pandemic. The described LFIA device having a control/sample dual-lane design serves this purpose with successful field-test data.

Aptamer-Based Lateral Flow Assays: Current Trends in Clinical Diagnostic Rapid Tests

The lateral flow assay (LFA) is an extensively used paper-based platform for the rapid and on-site detection of different analytes. The method is user-friendly with no need for sophisticated operation and only includes adding sample. Generally, antibodies are employed as the biorecognition elements in the LFA. However, antibodies possess several disadvantages including poor stability, high batch-to-batch variation, long development time, high price and need for ethical approval and cold chain. Because of these limitations, aptamers screened by an in vitro process can be a good alternative to antibodies as biorecognition molecules in the LFA. In recent years, aptamer-based LFAs have been investigated for the detection of different analytes in point-of-care diagnostics. In this review, we summarize the applications of aptamer technology in LFAs in clinical diagnostic rapid tests for the detection of biomarkers, microbial analytes, hormones and antibiotics. Performance, advantages and drawbacks of the developed assays are also discussed.

Comparison of enzyme-linked immunosorbent assay and Fassisi® bovine immunoglobulin G (IgG) immunoassay for quantification of bovine IgG in neonatal calf serum

Background and Aim: Rapid tests are routinely used to estimate serum immunoglobulin G (IgG) concentrations in diagnosing a failure of passive transfer (FPT) in calves. The study aimed to compare the Fassisi® Bovine IgG (FB-IgG) immunoassay and an enzyme-linked immunosorbent assay for quantifying bovine IgG in neonatal calf serum. Materials and Methods: A total of 277 calves of 1-10 days of age were used in this study. Blood samples were obtained, and serum was extracted by centrifuging the samples at 2740× g for 5 min at 20°C. The serum was analyzed using the FB-IgG according to the manufacturer's specifications. Serum IgG concentrations were also determined by enzyme-linked immunosorbent assay (ELISA-IgG). FPT was defined as a serum IgG concentration <10 mg/mL. Results: The mean ELISA-IgG serum concentration was 8.40 mg/mL (SD=7.02, range=0.10-47.50 mg/mL). FPT prevalence based on the ELISA measurements was 66.8%. The prevalence of partial and full FPT based on the FB-IgG was 54.5%. The ELISA-IgG and FB-IgG results were subjected to correlation and regression analysis. Overall sensitivity and specificity of the FB-IgG were 61.1% and 58.7%, respectively. A statistically significant dependence on age was identified in the results. Conclusion: Our findings suggest that the FB-IgG rapid method is less accurate and provides no other advantages over established methods.

Analytical sensitivity of seven SARS-CoV-2 antigen-detecting rapid tests for Omicron variant

The emergence of novel SARS-CoV-2 variants of concern (VOCs) requires investigation of a potential impact on diagnostic performance, especially on Antigen-detecting rapid antigenic tests (Ag-RDT). Although anecdotal reports have been circulating that Omicron is in principle detected by several Ag-RDTs, no published data are a yet available for the newly emerged Omicron variant. Here, we have performed an analytical sensitivity testing with cultured virus in seven Ag-RDTs for their sensitivity to Omicron compared to data earlier obtained on VOCs Alpha, Beta Gamma and Delta and a pre-VOC isolate of SARS-CoV-2. Overall, we have found a tendency towards lower sensitivity for Omicron compared to pre-VOC SARS-CoV-2 and the other VOCs across tests. Importantly, while analytical testing with cultured virus may be a proxy for clinical sensitivity, is not a replacement for clinical evaluations which are urgently needed for Ag-RDT performance in Omicron-infected individuals.

Comparing the Performance of HIV Rapid Diagnostic Tests Used in Zambia: a Systematic Review of Clinical Data.

Objective: To investigate the performance of the HIV RDTs used in Zambia. Method: 2,564 participants aged between 15 and 95 years from two sites in Lusaka province years were tested on OraQuick ADVANCE, Abbot Determine, and then confirmed on Uni-Gold Recombigen. The data from the participants were analyzed using SPSS version 25.0. Results: The 3 RDTs when compared to the 4th generation Abbot Architect results had the following results: OraQuick ADVANCE, Alere Determine and Uni-Gold Ultra, at 95% CI had Sensitivities of: 91.8%, 93.3% and 92.5% respectively. The specificities of OraQuick ADVANCE and Uni-Gold were the same (100.0%; 95% CI: 98.8 -100.0) but slightly different from Alere Determine (99.8%). Positive predictive values at 95% CI were 100% for OraQuick ADVANCE and Uni-Gold and 98.4% for Alere Determine. Negative predictive values (at 95% CIs) were 99.1, 99.2 and 99.1 for OraQuick ADVANCE, Alere Determine, and Uni-Gold Ultra respectively. The results showed that these RDTs could only detect 12 out of every 13 HIV positive results. Conclusion: Third generation RDTs are not effective in detecting acute positive cases. Fourth generation Rapid Tests are required to capture the positive cases being missed out.

COVID-19 impact on testing, diagnosis and care of people with sexually transmitted infections in a low human development region, Minas Gerais, Brazil

This study aimed to analyze the impact of the COVID-19 pandemic on the care of people with Sexually Transmitted Infections (STIs) in a region of low human development, located in Minas Gerais, Brazil. Methods: The number of monthly procedures during pandemic period, January to December 2020, and comparison period, January to December 2019, in a SUS regional clinic, a reference for STIs, were analyzed. Visits were categorized into follow-up appointments, rapid tests, viral loads and first appointment due a recent diagnosis. Comparison between both periods was performed by frequency analysis, difference in the mean monthly attendances (DM) and prevalence ratios (PR), considering ratio between the proportion of attendances in the pandemic period/proportion of attendances in the comparative period. During the pandemic period, the average number of monthly consultations reduced for all consultations (DM = -105.25) and categories. Proportion of consultations reduced for rapid tests (PR = 0.46; 95% CI = 0.41-0.52) and first consultation due recent diagnosis (PR = 0.90; 95% CI = 0.65-1, 25), procedures that are usually scheduled by the user. There was an increase in the proportion of follow-up visits (PR = 1.18; 95% CI = 1.09-1.27) and viral load tests (PR = 1.41; 95% CI = 1.32-1, 88), monitoring procedures usually scheduled by the clinic. There was a trend to maintain risk exposure for STIs. Conclusion: These findings may guide better strategies to care for individuals with STIs.

DETERMINATION OF PAIN IN PATIENTS WITH ACUTE CALCULOUS CHOLECYSTITIS IN PATIENTS WITH CHRONIC HEPATITIS

The aim. To establish the diagnostic value of the scale for assessing the severity of pain by determining the intensity of pain in patients with acute calculous cholecystitis in patients with chronic viral hepatitis. Materials and methods of research. The study was conducted in the period from 2016 to 2021 in the Department of Emergency Surgery of the Military Medical Clinical Center. In the first stage, the diagnostic scheme included only surveys to identify potential risk factors for infection and anamnestic data on the presence of HCV diagnosed in the past. In the second stage, rapid tests for antigens and antibodies to HCV were introduced into the diagnostic scheme along with the survey. Research results. Patients respond differently to pain, and the sen sation of pain is individual and subjective. Conclusions. Quantitative assessment and registration of the inten sity of pain using a visual-analog scale can supplement the comprehensive information about the general condition of the patient, which is necessary to select the optimal treatment in emergency surgery.