Analytical performance evaluation of Lumipulse® SARS-CoV-2 antigen assay in 392 asymptomatic patients.

INTRODUCTION: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is one of the current public health care challenges. The main strategy adopted to prevent the spread of infection is the rapid identification of COVID-19-positive subjects. The aim of this study was to compare the performance of Lumipulse® antigen immunoassay with the real-time RT-PCR, the gold standard for the diagnosis of SARS-CoV-2 infection, in a strictly selected asymptomatic population. MATERIALS AND METHODS: A total of 392 consecutive oro-nasopharyngeal swabs were collected from patients with no symptoms related to COVID-19 at the Emergency Department of AORN Sant'Anna e San Sebastiano, Caserta, Italy to evaluate the analytical performance of Lumipulse® SARS-CoV-2 antigen compared to qualitative real-time RT-PCR in asymptomatic patients. RESULTS: Lumipulse® SARS-CoV-2 antigen assay shows an overall agreement rate of 97% with a sensitivity of 96% and a specificity of 98%, with a PPV and NPV of 97%. The sensitivity varies according to the cycle threshold (Ct )-value reaching 100% and 86% with 15 < Ct < 25 and Ct ≥ 25, respectively. The ROC analysis yielded an AUC value of 0.98, suggesting that the antigen test may accurately detect SARS-CoV-2. CONCLUSION: Our data showed that Lumipulse® SARS-CoV-2 antigen assay might be an efficient tool in the identification and limitation of SARS-CoV-2 transmission in large asymptomatic populations.

Durability of Humoral Immune Responses to SARS-CoV-2 in Citizens of Ariano Irpino (Campania, Italy): A Longitudinal Observational Study With an 11.5-Month Follow-Up.

As of November 17, 2021, SARS-CoV-2 (Severe Acute Respiratory Syndrome CoronaVirus 2), the causative agent of COVID-19 (COronaVIrus Disease 19), has infected ~250 million people worldwide, causing around five million deaths. Titers of anti-SARS-CoV-2 neutralizing antibodies were relatively stable for at least 9 months in a population-based study conducted in Wuhan, China, both in symptomatic and in asymptomatic individuals. In the mass screening campaign conducted in the town of Ariano Irpino (Avellino, Italy) in May, 2020, 5.7% (95% CI: 5.3-6-1) of the 13,444 asymptomatic citizens screened were positive for anti-nucleocapsid antibodies against SARS-CoV-2. Among these, 422 citizens were re-tested for anti SARS-CoV-2 antibodies in January, 2021 and/or in April, 2021 and enrolled in this longitudinal observational study. Median (interquartile range) age of the study cohort was 46 years (29-59), with 47 (11.1%) participants of minor age, while 217 (51.4%) participants were females. There was no evidence of re-infection in any of the subjects included. Presence of anti-nuclear antibodies antibodies (Elecysis, Roche) was reported in 95.7 and 93.7% of evaluable participants in January and April, 2021. Multiple logistic regression analysis used to explore associations between age, sex and seroprevalence showed that adults vs. minors had significantly lower odds of having anti-S1 antibodies (Biorad) both in January, 2021 and in April, 2021. Our findings showed that antibodies remained detectable at least 11.5 months after infection in >90% of never symptomatic cases. Further investigation is required to establish duration of immunity against SARS-CoV-2.

Clinical Outcome Prediction in COVID-19 Patients by Lymphocyte Subsets Analysis and Monocytes' iTNF-α Expression.

In December 2019, a novel coronavirus, "SARS-CoV-2", was recognized as the cause of coronavirus disease 2019 (COVID-19). Several studies have explored the changes and the role of inflammatory cells and cytokines in the immunopathogenesis of the disease, but until today, the results have been controversial. Based on these premises, we conducted a retrospective assessment of monocyte intracellular TNF-α expression (iTNF-α) and on the frequencies of lymphocyte sub-populations in twenty-five patients with moderate/severe COVID-19. We found lymphopenia in all COVID-19 infected subjects compared to healthy subjects. On initial observation, in patients with favorable outcomes, we detected a high absolute eosinophil count and a high CD4+/CD8+ T lymphocytes ratio, while in the Exitus Group, we observed high neutrophil and CD8+ T lymphocyte counts. During infection, in patients with favorable outcomes, we observed a rise in the lymphocyte count, in the monocyte and in Treg lymphocyte counts, and in the CD4+ and in CD8+ T lymphocytes count but a reduction in the CD4+/CD8+ T lymphocyte ratio. Instead, in the Exitus Group, we observed a reduction in the Treg lymphocyte counts and a decrease in iTNF-α expression. Our preliminary findings point to a modulation of the different cellular mediators of the immune system, which probably play a key role in the outcomes of COVID-19.