Clinical usefulness of testing for severe acute respiratory syndrome coronavirus 2 antibodies.

In the COVID-19 pandemic era, antibody testing against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has proven an invaluable tool and herein we highlight some of the most useful clinical and/or epidemiological applications of humoral immune responses recording. Anti-spike circulating IgGs and SARS-CoV-2 neutralizing antibodies can serve as predictors of disease progression or disease prevention, whereas anti-nucleocapsid antibodies can help distinguishing infection from vaccination. Also, in the era of immunotherapies we address the validity of anti-SARS-CoV-2 antibody monitoring post-infection and/or vaccination following therapies with the popular anti-CD20 monoclonals, as well as in the context of various cancers or autoimmune conditions such as rheumatoid arthritis and multiple sclerosis. Additional crucial applications include population immunosurveillance, either at the general population or at specific communities such as health workers. Finally, we discuss how testing of antibodies in cerebrospinal fluid can inform us on the neurological complications that often accompany COVID-19.

Second Booster BNT162b2 Restores SARS-CoV-2 Humoral Response in Patients With Multiple Myeloma, Excluding Those Under Anti-BCMA Therapy.

COVID-19 vaccination leads to a less intense humoral response in patients with multiple myeloma (MM) compared with healthy individuals, whereas the SARS-CoV-2-specific immunity fades over time. The purpose of this study was to explore the kinetics of SARS-CoV-2 neutralizing antibodies (NAbs) in patients with MM after vaccination with the BNT162b2 mRNA vaccine, focusing on their response before (B4D) and at 1 month after the fourth vaccination (M1P4D). Overall, 201 patients with a median age of 67 years were included, whereas 114 (56.7%) were men. The median NAbs levels B4D were 80.0% (±3.5%) and at M1P4D they increased to a median value of 96.1% (±3.7%). The NAb values at M1P4D were similar to those at 1 month post the third dose and superior to all previous timepoints. At M1P4D, the NAbs levels of all the treatment groups increased, apart from the anti-BCMA group. A significant increase in median NAbs values was observed for those receiving CD38-based treatment (n = 43, from 71.0% B4D to 96.0% at M1P4D) and those who did not receive CD38- or BCMA-targeted therapy (n = 137, from 89.6% B4D to 96.3% at M1P4D). Regarding the patients under BCMA-based therapy (n = 21), there was no remarkable increase in NAbs values following the second booster shot (from 3.0% B4D to 4.0% at M1P4D). In conclusion, booster vaccination with the BNT162b2 results in a substantially improved humoral response against SARS-CoV-2 in patients with MM. Anti-BCMA treatment remains an adverse predictive factor for NAbs response; thus, tailored prevention measures should be considered for this patient subgroup.

Adverse effects of COVID-19 mRNA vaccines: the spike hypothesis.

Vaccination is a major tool for mitigating the coronavirus disease 2019 (COVID-19) pandemic, and mRNA vaccines are central to the ongoing vaccination campaign that is undoubtedly saving thousands of lives. However, adverse effects (AEs) following vaccination have been noted which may relate to a proinflammatory action of the lipid nanoparticles used or the delivered mRNA (i.e., the vaccine formulation), as well as to the unique nature, expression pattern, binding profile, and proinflammatory effects of the produced antigens - spike (S) protein and/or its subunits/peptide fragments - in human tissues or organs. Current knowledge on this topic originates mostly from cell-based assays or from model organisms; further research on the cellular/molecular basis of the mRNA vaccine-induced AEs will therefore promise safety, maintain trust, and direct health policies.

Anti-SARS-CoV-2 Antibodies Within IVIg Preparations: Cross-Reactivities With Seasonal Coronaviruses, Natural Autoimmunity, and Therapeutic Implications.

Introduction: Cross-reactivity to SARS-CoV-2 antigenic peptides has been detected on T-cells from pre-pandemic donors due to recognition of conserved protein fragments within members of the coronavirus's family. Further, preexisting antibodies recognizing SARS-CoV-2 with conserved epitopes in the spike region have been now seen in uninfected individuals. High-dose Intravenous Immunoglobulin (IVIg), derived from thousands of healthy donors, contains natural IgG antibodies against various antigens which can be detected both within the IVIg preparations and in the serum of IVIg-receiving patients. Whether IVIg preparations from pre-pandemic donors also contain antibodies against pre-pandemic coronaviruses or autoreactive antibodies that cross-react with SARS-CoV-2 antigenic epitopes, is unknown. Methods: 13 samples from 5 commercial IVIg preparations from pre-pandemic donors (HyQvia (Baxalta Innovations GmbH); Privigen (CSL Behring); Intratect (Biotest AG); IgVena (Kedrion S.p.A); and Flebogamma (Grifols S.A.) were blindly screened using a semi-quantitative FDA-approved and validated enzyme-linked immunosorbent assay (ELISA) (Euroimmun, Lubeck, Germany). Results: Nine of thirteen preparations (69.2%), all from two different manufactures, were antibody-positive based on the defined cut-off positivity (index of sample OD to calibrator OD > 1.1). From one manufacturer, 7/7 lots (100%) and from another 2/3 lots (67%), tested positive for cross-reacting antibodies. 7/9 of the positive preparations (77%) had titers as seen in asymptomatically infected individuals or recent COVID19-recovered patients, while 2/9 (23%) had higher titers, comparable to those seen in patients with active symptomatic COVID-19 infection (index > 2.2). Conclusion: Pre-pandemic IVIg donors have either natural autoantibodies or pre-pandemic cross-reactive antibodies against antigenic protein fragments conserved among the "common cold" - related coronaviruses. The findings are important in: (a) assessing true anti-SARS-CoV-2-IgG seroprevalence avoiding false positivity in IVIg-receiving patients; (b) exploring potential protective benefits in patients with immune-mediated conditions and immunodeficiencies receiving acute or chronic maintenance IVIg therapy, and (c) validating data from a recent controlled study that showed significantly lower in-hospital mortality in the IVIg- treated group.

Anti-SARS-CoV-2 antibodies in the CSF, blood-brain barrier dysfunction, and neurological outcome: Studies in 8 stuporous and comatose patients.

OBJECTIVE: To investigate the pathophysiologic mechanism of encephalopathy and prolonged comatose or stuporous state in severally ill patients with coronavirus disease 2019 (COVID-19). METHODS: Eight COVID-19 patients with signs of encephalopathy were tested for antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the serum and CSF using a Food and Drug Administration-approved and independently validated ELISA. Blood-brain barrier (BBB) integrity and immunoglobulin G (IgG) intrathecal synthesis were further tested using albumin and IgG indices. The CSF was also tested for autoimmune encephalitis antibodies and 14-3-3, a marker of ongoing neurodegeneration. RESULTS: All patients had anti-SARS-CoV-2 antibodies in their CSF, and 4 of 8 patients had high titers, comparable to high serum values. One patient had anti-SARS-CoV-2 IgG intrathecal synthesis, and 3 others had disruption of the blood-brain barrier. The CSF in 4 patients was positive for 14-3-3-protein suggesting ongoing neurodegeneration. In all patients, the CSF was negative for autoimmune encephalitis antibodies and SARS-CoV-2 by PCR. None of the patients, apart from persistent encephalopathic signs, had any focal neurologic signs or history or specific neurologic disease. CONCLUSIONS: High-titer anti-SARS-CoV-2 antibodies were detected in the CSF of comatose or encephalopathic patients demonstrating intrathecal IgG synthesis or BBB disruption. A disrupted BBB may facilitate the entry of cytokines and inflammatory mediators into the CNS enhancing neuroinflammation and neurodegeneration. The observations highlight the need for prospective CSF studies to determine the pathogenic role of anti-SARS-CoV-2 antibodies and identify early therapeutic interventions.