Analysis of humoral and cellular immunity after SARS-CoV-2 vaccination in patients with multiple sclerosis treated with immunomodulatory drugs.

We analyzed immune response to SARS-CoV-2 vaccination by measuring specific IgG titers and T-cell reactivity to different SARS-CoV-2 peptides in multiple sclerosis patients taking different disease-modifying treatments. Of the 88 patients included, 72 developed any kind of immune response after vaccination. Although DMTs such as fingolimod and anti-CD20+ treatments prevented patients from developing a robust humoral response to the vaccine, most of them were still able to develop a cellular response, which could be crucial for long-term immunity. It is probably advisable that all MS patients take additional/booster doses to increase their humoral and/or cellular immune response to SARS-CoV-2.

Development of an Effective Immune Response in Adults With Down Syndrome After Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Vaccination.

BACKGROUND: Immune dysregulation in individuals with Down syndrome (DS) leads to an increased risk for hospitalization and death due to coronavirus disease 2019 (COVID-19) and may impair the generation of protective immunity after vaccine administration. METHODS: The cellular and humoral responses of 55 individuals with DS who received a complete SARS-CoV-2 vaccination regime at 1 to 3 (visit [V 1]) and 6 (V2) months were characterized. RESULTS: SARS-CoV-2-reactive CD4+ and CD8+ T lymphocytes with a predominant Th1 phenotype were observed at V1 and increased at V2. Likewise, an increase in SARS-CoV-2-specific circulating Tfh (cTfh) cells and CD8+ CXCR5+ PD-1hi lymphocytes was already observed at V1 after vaccine administration. Specific immunoglobulin G (IgG) antibodies against SARS-CoV-2 S protein were detected in 96% and 98% of subjects at V1 and V2, respectively, although IgG titers decreased significantly between both time points. CONCLUSIONS: Our findings show that DS individuals develop an effective immune response to usual regimes of SARS-CoV-2 vaccination.

Evaluation of two RT-PCR techniques for SARS-CoV-2 RNA detection in serum for microbiological diagnosis.

Presence of SARS-CoV-2 RNA in serum (viremia) of COVID-19 patients has been related to poor prognosis and death. The aim of this study was to evaluate both the ability to detect viremia in COVID-19 patients of two commercial reverse real-time-PCR (rRT-PCR) tests, Cobas® and TaqPath™, comparing them with a gold standard method, and their implementation in microbiology laboratories. This retrospective cohort study included 303 adult patients (203 diagnosed with COVID-19 and 100 non-COVID-19 patients) admitted to a tertiary hospital, with at least one serum sample collected within the first 48 h from admission. A total of 365 serum samples were included: 100 from non-COVID patients (pre-pandemic and pandemic control groups) and 265 from COVID-19 patients. Serum samples were considered positive when at least one target was detected. All patients in control groups showed negative viremia. Cobas® and TaqPath™ tests showed specificity and Positive Predictive Value over 96%. Nevertheless, sensitivity (53.72 and 73.63, respectively) and Negative Predictive Value (64.78 and 75) were lower. Viremia difference between ICU and non-ICU patients was significant (p ≤ 0.001) for both techniques. Consequently, SARS-CoV-2 viremia detection by both rRT-PCR tests should be considered a good tool to stratify COVID-19 patients and could be implemented in microbiology laboratories.

Evaluation of diagnostic accuracy of 10 serological assays for detection of SARS-CoV-2 antibodies.

Antibody detection is essential to establish exposure, infection, and immunity to SARS-CoV-2, as well as to perform epidemiological studies. The worldwide urge for new diagnostic tools to control the pandemic has led to a quick incorporation in clinical practice of the recently developed serological assays. However, as only few comparative studies have been published, there is a lack of data about the diagnostic accuracy of currently available assays. We evaluated the diagnostic accuracy to detect Ig G, Ig M+A, and/or IgA anti SARS-CoV-2 of 10 different assays: lateral flow card immunoassays, 4 enzyme-linked immunosorbent assay (ELISA), and 3 chemiluminescent particle immunoassays (CMIA). Using reverse transcriptase polymerase chain reaction (RT-PCR) for COVID-19 as gold standard, sensitivity, specificity, PPV, and NPV were determined. Each assay was tested in 2 groups, namely, positive control, formed by 50 sera from 50 patients with SARS-CoV-2 pneumonia with positive RT-PCR; and negative control, formed by 50 sera from 50 patients with respiratory infection non-COVID-19. Sensitivity range of the 10 assays evaluated for patients with positive COVID-19 RT-PCR was 40-77% (65-81% considering IgG plus IgM). Specificity ranged 83-100%. VPP and VPN were respectively 81-100% and 61.6-81%. Among the lateral flow immunoassays, the highest sensitivity and specificity results were found in Wondfo® SARS-CoV-2 Antibody Test. ELISA IgG and IgA from EUROIMMUN® were the most sensitive ELISA. However, poor results were obtained for isolated detection of IgG. We found similar sensitivity for IgG with SARS-CoV-2 for Architect by Abbott® and ELISA by Vircell®. Results obtained varied widely among the assays evaluated. Due to a better specificity, overall diagnostic accuracy of the assays evaluated was higher in case of positive result. On the other side, lack of antibody detection should be taken with care because of the low sensitivity described. Highest diagnostic accuracy was obtained with ELISA and CMIAs, but they last much longer.