Effectiveness of Anti-SARS-CoV-2 monoclonal antibodies in real-life: RNAemia and clinical outcomes in high-risk COVID-19 patients

Background Anti-SARS-CoV-2 neutralizing monoclonal antibodies (mAbs) have been shown to have clinical benefits in treating high-risk patients with mild-moderate COVID-19. SARS-CoV-2 RNA in serum (RNAemia), is usually associated with severe disease and deaths. This study evaluates real-life data on the effectiveness of mAbs therapies against SARS-CoV-2 infections by different viral variants, particularly in the presence of RNAemia, focusing on clinical outcomes. Methods From March 2021 to May 2022, high-risk patients with PCR-confirmed mild-moderate COVID-19 were enrolled at the Clinic of Infectious Diseases, San Paolo Hospital in Milan. Patients received Bamlanivimab/Bamlanivimab + Etesevimab/Casirivimab + Imdevimab/Sotrovimab based on Agenzia Italiana del Farmaco (AIFA) guidelines and prevalent SARS-CoV-2 variants. Nasopharyngeal swabs (NPS) and plasma samples were collected at infusion (t0) and after 7 days (t1). NPS viral loads and RNAemia were quantified using RT-qPCR, and variant typing was conducted. Clinical outcomes were evaluated, including time to symptom resolution and adverse effects. Results Among 176 enrolled patients, treatment efficacy was observed in 96.6% with a median time to symptom resolution of 12 days (IQR 10–19). Viral load significantly decreased in both NPS and plasma by day 7 post-treatment (p<0.001). At t0, RNAemia was present in 61.9% of patients and NPS viral loads were higher in patients with RNAemia (p=0.002). However, after treatment, no significant differences in viral loads and times to symptom resolution were noted between patients with and without RNAemia. Omicron-infected patients exhibited higher plasma viral loads compared to Alpha and Delta variants (p<0.001) and the presence of RNAemia was significantly associated with Omicron (p<0.001). Vaccinated patients achieved faster recovery regardless of variant type (p=0.001). Conclusion Early administration of anti-SARS-CoV-2 mAbs in high-risk patients significantly reduced viral loads in NPS and plasma and improved clinical outcomes. Despite the presence of RNAemia, these tailored mAb therapies led to favorable recovery times and minimal adverse effects

Flow Cytometry Analysis of CD4⁺ and CD8⁺ T Lymphocytes in COVID- 19 Patients

The clinical presentation of COVID-19 varies greatly from case to another, with host characteristics playing a pivotal role. The immune system is a pivotal function in establishing the course of SARS-COV-2 infection. Severe instances of COVID-19 and the resulting death are caused less by the virus itself than by the destructive unrestrained immune response. Among the host determinants for poor disease prognosis is probably genetic vulnerability to dysregulated immune response. The objective of this work is to examine some of the host genetic variables that are being studied in relation to the severity of COVID-19. The complex relationship between autoimmunity and the pathophysiology of COVID-19 was examined. Patients with COVID-19 were recruited from AL-Dewaniyah Teaching Hospital and AL-Hussain Teaching Hospital in Karbala city. All patients had been diagnosed with the virus using real-time polymerase chain reaction. A total of 70 blood samples (35 from the mild group, 35 from the severe group, and 35 from the controlled group) were obtained in EDTA tubes. Orderly to investigate the correlation between the progression of disease and variations in specific regions of host immunoassays had been used by flow cytometry. The results of the flow cytometry were reported as the average percentage of positive cells for CD4 and CD8 immunological markers. Cases with COVID-19 had a substantially lower mean CD4 concentration than the healthy patients. Furthermore, the mean concentration of CD8 was significantly lower in cases with COVID-19 than in healthy. In addition, there is significant (P 0.001) decline in both CD4 and CD8 mean levels between patients with severe and mild COVID-19

Disparities in response to mRNA SARS-CoV-2 vaccines according to sex and age: A systematic review

BACKGROUND The rapid development and distribution of mRNA COVID-19 vaccines has been essential in containing the SARS-CoV-2 epidemic around the globe. For ongoing and future immunization campaigns globally, there is a need to evaluate the impact of population demographics such as age and sex, on vaccine efficacy and safety. METHODS This systematic review (PROSPERO ID CRD42023328245) conducted according to PRISMA guidelines evaluates the impact of age and sex on the safety and efficacy of the mRNA COVID-19 vaccinations administrated in 15 studies that were chosen according to strict criteria. The ROBIS tool was applied to evaluate the robustness and the quality of the studies included in the review. RESULTS After screening, 15 studies satisfied the inclusion criteria. The results showed that the COVID-19 mRNA vaccines typically elicit robust immune responses, and that younger people have higher antibody levels. Comparing the sexes reveals that higher immunological responses were induced in females, and mild to moderate adverse effects (such as injection site discomfort, exhaustion, and headaches) were also more frequently reported in women. Despite these variations, COVID-19 vaccines have been found to be safe to use across diverse populations, which supports their extensive use in public health initiatives. CONCLUSION Our results suggests that tailored vaccination may achieve maximum effectiveness and better tolerability depending on age and sex. Currently study results are rarely stratified by age and sex and this is a deficit in clinical trial publications. More research is needed to elucidate the biological mechanisms underlying the variations in vaccine responses according to age and sex

Simulation-driven design of stabilized SARS-CoV-2 spike S2 immunogens.

The full-length prefusion-stabilized SARS-CoV-2 spike (S) is the principal antigen of COVID-19 vaccines. Vaccine efficacy has been impacted by emerging variants of concern that accumulate most of the sequence modifications in the immunodominant S1 subunit. S2, in contrast, is the most evolutionarily conserved region of the spike and can elicit broadly neutralizing and protective antibodies. Yet, S2s usage as an alternative vaccine strategy is hampered by its general instability. Here, we use a simulation-driven approach to design S2-only immunogens stabilized in a closed prefusion conformation. Molecular simulations provide a mechanistic characterization of the S2 trimers opening, informing the design of tryptophan substitutions that impart kinetic and thermodynamic stabilization. Structural characterization via cryo-EM shows the molecular basis of S2 stabilization in the closed prefusion conformation. Informed by molecular simulations and corroborated by experiments, we report an engineered S2 immunogen that exhibits increased protein expression, superior thermostability, and preserved immunogenicity against sarbecoviruses

Safety and immunogenicity of ChAdOx1 nCoV-19 (AZD1222) vaccine in adults in Kenya: a phase 1/2 single-blind, randomised controlled trial

Background: There are limited data on the immunogenicity of coronavirus disease 2019 (COVID-19) vaccines in African populations. Here we report the immunogenicity and safety of the ChAdOx1 nCoV-19 (AZD1222) vaccine from a phase 1/2 single-blind, randomised, controlled trial among adults in Kenya conducted as part of the early studies assessing vaccine performance in different geographical settings to inform Emergency Use Authorisation. Methods: We recruited and randomly assigned (1:1) 400 healthy adults aged ≥18 years in Kenya to receive ChAdOx1 nCoV-19 or control rabies vaccine, each as a two-dose schedule with a 3-month interval. The co-primary outcomes were safety, and immunogenicity assessed using total IgG enzyme-linked immunosorbent assay (ELISA) against SARS-CoV-2 spike protein 28 days after the second vaccination. Results: Between 28th October 2020 and 19th August 2021, 400 participants were enrolled and assigned to receive ChAdOx1 nCoV-19 (n=200) or rabies vaccine (n=200). Local and systemic adverse events were self-limiting and mild or moderate in nature. Three serious adverse events were reported but these were deemed unrelated to vaccination. The geometric mean anti-spike IgG titres 28 days after second dose vaccination were higher in the ChAdOx1 group (2773 ELISA units [EU], 95% CI 2447, 3142) than in the rabies vaccine group (61 EU, 95% CI 45, 81) and persisted over the 12 months follow-up. We did not identify any symptomatic infections or hospital admissions with respiratory illness and so vaccine efficacy against clinically apparent infection could not be measured. Vaccine efficacy against asymptomatic SARS-CoV-2 infection was 38.4% (95% CI -26.8%, 70.1%; p=0.188). Conclusions: The safety, immunogenicity and efficacy against asymptomatic infection of ChAdOx1 nCoV-19 among Kenyan adults was similar to that observed elsewhere in the world, but efficacy against symptomatic infection or severe disease could not be measured in this cohort. Pan-African Clinical Trials Registration: PACTR202005681895696 (11/05/2020

Humoral immune response after SARS-CoV-2 infection or vaccination

Die humorale Immunität nach einer Infektion oder Impfung gegen das Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) spielt eine entscheidende Rolle bei der Eindämmung der Virusübertragung sowie der. In dieser Studie verwendeten wir einen kommerziellen Anti-Spike-IgG-Assay (S-IgG) und entwickelten einen zellkulturbasierten Neutralisationstest, um den Verlauf neutralisierender Antikörper bei SARS-CoV-2-infizierten und geimpften Personen über längere Zeit zu untersuchen. Unsere Ergebnisse zeigen, dass auch mehr als ein Jahr nach einer Infektion etwa 78 % der beobachteten Studienteilnehmer seropositiv für S-IgG-Antikörper blieben. Zudem wiesen die Seren der Infizierten eine stabile Neutralisationskapazität in einem Neutralisationstest gegen einen SARS-CoV-2-Isolat von März 2020 auf. Freiwillige, die entweder eine homologe Prime-Boost-Impfung mit BNT162b2 oder eine heterologe AZD1222-Prime/mRNA-Booster-Impfung erhielten, zeigten höhere Spiegel neutralisierender Antikörper im Vergleich zu Personen mit mildem Infektionsverlauf, was die hohe Wirksamkeit der verfügbaren Impfstoffe unterstreicht. Darüber hinaus konnten wir die Verlässlichkeit eines kommerziellen Assay, welcher S-IgG-Spiegel misst, zur Vorhersage der Neutralisationskapazität nachweisen: 94,8 % der seropositiven Proben wiesen einen Neutralisationstiter von ≥1:10 auf. Damit stellt S-IgG einen kostengünstigen und leicht bestimmbaren Surrogatparameter für die Neutralisationskapazität dar

Host-control of HIV:Balance between immunity and immunopathology

Infection with HIV-1 is characterized by a gradual decline in CD4 T cells as well as chronic activation of the immune system. The balance between an adequate immune response on one side and overstimulation and immune dysfunction on the other, influences the highly variable disease course of untreated HIV-1 infection. Current antiretroviral therapy suppresses viral replication efficiently however, it does not completely restore the immune system and some level of immune activation and inflammation persists. Understanding the mechanisms of HIV-1 pathogenesis could provide novel avenues for treatment of HIV-1 infection and restoration of the observed immune imbalance. In this thesis, the immune response to HIV-1 infection in relation to disease progression and disease control is explored at the level of both the innate and the adaptive immune response. The findings of this thesis contribute to expanding our knowledge on the immune response to HIV-1 infection

Study of the acquisition and maintenance of antibody and cellular immune responses against SARS-CoV-2 in longitudinal cohorts

Programa de Doctorat en Medicina i Recerca Translacional[eng] The COVID-19 pandemic has underscored the importance of understanding adaptive immune responses to SARS-CoV-2 to optimize vaccination strategies and public health interventions. Adaptive immune responses generate immune memory, which is essential for preventing reinfections, facilitating rapid virus clearance and reducing disease severity. Neutralizing antibodies prevent viral infection and T cells support antibody production and eliminate infected cells. Despite extensive research on SARS- CoV-2 adaptive responses, evidence was scarce early in the COVID-19 pandemic, and knowledge gaps persist, such as their duration, factors influencing them, and the cross- recognition of emerging variants, key aspects to improve immunological protection. We characterized antibody and T-cell responses induced by SARS-CoV-2 infection, COVID-19 vaccination, or a combination of both against the ancestral virus and emerging variants over three years since the onset of the pandemic. Antibody levels against spike (S) and nucleocapsid (N) antigens were measured using Luminex assays, neutralizing capacity through pseudovirus assays, and T-cell responses to S, N and membrane antigens using IFN-γ/IL-2 FluoroSpot and activation induced marker assays. Antibody kinetics were modeled using linear mixed models, and determinants were analyzed with multivariable linear regression models. The results demonstrated that positive antibody and T-cell responses to S persisted for at least three years following infection during the first pandemic wave and two years after vaccination, with subsequent exposures (boosters and reinfections) supporting the maintenance. Antibody kinetics varied by isotype, antigen, and immunization type, showing greater durability in individuals with hybrid immunity and those receiving three vaccinations compared to two. These responses were heterogeneous, influenced by factors such as comorbidities and SARS-CoV-2 prior exposure. Infection as the first SARS-CoV-2 encounter was associated with weaker antibody responses against Omicron subvariants BA.1, BA.2, BA.4/5, BQ.1.1, and XBB, but with stronger T-cell responses after three years compared to vaccination as first antigen encounter. Although ancestral pre-existing antibodies showed reduced recognition of Beta, Gamma, Delta, and Omicron subvariants BA.1, BA.2, BA.4/5, BQ.1.1, XBB, with lost neutralization for BA.2.86, T cells effectively recognized BA.2.86. In conclusion, these findings contribute to a deeper knowledge of COVID-19 immunity for optimizing vaccination strategies to maximize protection against SARS-CoV-2 and future emerging variants.[cat] La pandèmia de COVID-19 ha posat en manifest la importància de comprendre les respostes immunitàries adaptatives al SARS-CoV-2 per optimitzar les estratègies de vacunació i les intervencions de salut pública. Les respostes immunes adaptatives generen memòria immunitària, essencial per prevenir reinfeccions, eliminar el virus de manera ràpida i eficient i reduir la gravetat de la malaltia. Els anticossos neutralitzants impedeixen la infecció viral, mentre que els limfòcits T contribueixen a la producció d’anticossos i a l’eliminació de cèl·lules infectades. Tot i la investigació extensiva de les respostes adaptatives al SARS-CoV-2, les evidències eren escasses al començament de la pandèmia de COVID-19, i encara hi ha preguntes per resoldre, com ara la seva durada, els factors que les influeixen, i el reconeixement creuat a les variants emergents, aspectes clau per millorar la protecció immunològica. Hem caracteritzat les respostes d’anticossos i limfòcits T induïdes per la infecció del SARS-CoV-2, la vacunació COVID-19, o una combinació d’ambdues enfront el virus original i de les variants emergents al llarg de tres anys des de l’inici de la pandèmia. Els nivells d’anticossos enfront els antígens espícula (S) i nucleocàpsida (N) s’han mesurat mitjançant assajos de Luminex, la seva capacitat neutralitzant amb pseudovirus, i les respostes específiques dels limfòcits T als antígens S, N i membrana amb els assajos FluoroSpot d’IFN-γ/IL-2 i d’inducció de marcadors d’activació. La cinètica d’anticossos s’ha modelitzat amb models lineals mixtes, mentre que els factors influents s’han analitzat amb models de regressió lineal multivariable. Els resultats han mostrat que les respostes positives d’anticossos i limfòcits T a S persisteixen almenys tres anys després de la infecció durant la primera onada de la pandèmia i dos anys després de la vacunació, amb exposicions subseqüents (dosis reforç o reinfeccions) afavorint el manteniment. La cinètica d’anticossos va variar segons l’isotip, l’antigen i el tipus d’immunització, sent més duradores en individus amb immunitat híbrida i amb tres vacunacions en comparació a dues. Aquestes respostes van ser heterogènies, influenciades per factors com comorbiditats i l’exposició prèvia al SARS-CoV-2. La infecció com a primer encontre amb el SARS-CoV-2 es va associar a una menor resposta d’anticossos enfront les subvariants d’Òmicron BA.1, BA.2, BA.4/5, BQ.1.1 i XBB, però va generar major resposta de limfòcits T al cap de tres anys en comparació a la vacunació com a primer encontre antigènic. Tot i que els anticossos preexistents dirigits al virus original van disminuir el reconeixement a les variants Beta, Gamma, Delta, i les subvariants d’Òmicron BA.1, BA.2, BA.4/5, BQ.1.1, XBB, fins i tot perdent la capacitat de neutralització a la variant BA.2.86, els limfòcits T la van reconèixer de manera eficient. En conclusió, aquests resultats contribueixen a un coneixement més profund de la immunologia de la COVID-19 per optimitzar les estratègies de vacunació i maximitzar la protecció enfront del SARS-CoV-2 i futures variants emergents.[spa] La pandemia de COVID-19 ha destacado la importancia de comprender las respuestas inmunitarias adaptativas frente al SARS-CoV-2 para optimizar las estrategias de vacunación e intervenciones de salud pública. Las respuestas inmunes adaptativas generan memoria inmunitaria, que es esencial para prevenir reinfecciones, facilitar una eliminación rápida del virus y reducir la gravedad de la enfermedad. Los anticuerpos neutralizantes previenen la infección viral, mientras que los linfocitos T contribuyen a la producción de anticuerpos y eliminan las células infectadas. A pesar de la extensa investigación, al inicio de la pandemia de COVID-19 las evidencias eran limitadas y aún persisten preguntas por resolver, como su duración, los factores que las influyen y el reconocimiento cruzado con las variantes emergentes, aspectos clave para mejorar la protección inmunológica. Hemos caracterizado las respuestas de anticuerpos y linfocitos T inducidas por la infección del SARS-CoV-2, vacunación COVID-19, o una combinación de ambas frente al virus ancestral y a las variantes emergentes durante los tres años transcurridos desde el inicio de la pandemia. Los niveles de anticuerpos frente los antígenos de la espícula (S) y la nucleocápside (N) se midieron con tecnología Luminex, la capacidad neutralizante mediante ensayos de pseudovirus, y las respuestas de linfocitos T a los antígenos S, N y membrana con ensayos de FluoroSpot IFN-γ/IL-2 e inducción de marcadores de activación. Las cinéticas de los anticuerpos se modelaron utilizando modelos lineales mixtos, y los factores influyentes se analizaron con modelos de regresión lineal multivariable. Los resultados demostraron que las respuestas positivas de anticuerpos y linfocitos T frente S persistieron al menos tres años después de la infección durante la primera ola en la pandemia, y dos años después de la vacunación, con exposiciones posteriores (dosis refuerzo y reinfecciones) contribuyendo al mantenimiento. Las cinéticas de los anticuerpos variaron según el isotipo, el antígeno y el tipo de inmunización, mostrando mayor durabilidad en individuos con inmunidad híbrida y aquellos que recibieron tres dosis de vacuna en comparación con dos. Estas respuestas fueron heterogéneas, influenciadas por factores como las comorbilidades y exposiciones previas al SARS-CoV-2. La infección como primer contacto con el SARS-CoV-2 se asoció con respuestas de anticuerpos más débiles frente a las subvariantes de Ómicron BA.1, BA.2, BA.4/5, BQ.1.1 y XBB, pero con respuestas de linfocitos T más robustas al cabo de tres años en comparación con la vacunación como primer contacto antigénico. Aunque los anticuerpos preexistentes dirigidos al virus ancestral mostraron un reconocimiento reducido a las variantes Beta, Gamma, Delta y subvariantes de Ómicron BA.1, BA.2, BA.4/5, BQ.1.1, XBB, con una pérdida de neutralización total a la variante BA.2.86, los linfocitos T reconocieron eficazmente BA.2.86. En conclusión, estos hallazgos contribuyen a un conocimiento más profundo de la inmunología de COVID-19 para optimizar las estrategias de vacunación y maximizar la protección frente al SARS-CoV-2 y futuras variantes emergentes