Long-term humoral signatures following acute pediatric COVID-19 and Multisystem Inflammatory Syndrome in Children.

BACKGROUND: Although most children experience mild symptoms during acute SARS-CoV-2 infection, some develop the severe post-COVID-19 complication, Multisystem Inflammatory Syndrome in Children (MIS-C). While acute presentations of COVID-19 and MIS-C have been well immunophenotyped, little is known about the lasting immune profile in children after acute illness. METHODS: Children 2 months-20 years of age presenting with either acute COVID-19 (n = 9) or MIS-C (n = 12) were enrolled in a Pediatric COVID-19 Biorepository at a single medical center. We deeply profiled humoral immune responses and circulating cytokines following pediatric COVID-19 and MIS-C. RESULTS: Twenty-one children and young adults provided blood samples at both acute presentation and 6-month follow-up (mean: 6.5 months; standard deviation: 1.77 months). Pro-inflammatory cytokine elevations resolved after both acute COVID-19 and MIS-C. Humoral profiles continue to mature after acute COVID-19, displaying decreasing IgM and increasing IgG over time, as well as stronger effector functions, including antibody-dependent monocyte activation. In contrast, MIS-C immune signatures, especially anti-Spike IgG1, diminished over time. CONCLUSIONS: Here, we show the mature immune signature after pediatric COVID-19 and MIS-C, displaying resolving inflammation with recalibration of the humoral responses. These humoral profiles highlight immune activation and vulnerabilities over time in these pediatric post-infectious cohorts. IMPACT: The pediatric immune profile matures after both COVID-19 and MIS-C, suggesting a diversified anti-SARS-CoV-2 antibody response after resolution of acute illness. While pro-inflammatory cytokine responses resolve in the months following acute infection in both conditions, antibody-activated responses remain relatively heightened in convalescent COVID-19. These data may inform long-term immunoprotection from reinfection in children with past SARS-CoV-2 infections or MIS-C.

Selective SARS-CoV2 BA.2 escape of antibody Fc/Fc-receptor interactions.

The number of mutations in the omicron (B.1.1.529) BA.1 variant of concern led to an unprecedented evasion of vaccine induced immunity. However, despite rise in global infections, severe disease did not increase proportionally and is likely linked to persistent recognition of BA.1 by T cells and non-neutralizing opsonophagocytic antibodies. Yet, the emergence of new sublineage BA.2, which is more transmissible than BA.1 despite relatively preserved neutralizing antibody responses, has raised the possibility that BA.2 may evade other vaccine-induced responses. Here, we comprehensively profiled the BNT162b2 vaccine-induced response to several VOCs, including omicron BA.1 and BA.2. While vaccine-induced immune responses were compromised against both omicron sublineages, vaccine-induced antibody isotype titers, and non-neutralizing Fc effector functions were attenuated to the omicron BA.2 spike compared to BA.1. Conversely, FcγR2a and FcγR2b binding was elevated to BA.2, albeit lower than BA.1 responses, potentially contributing to persistent protection against severity of disease.

Occupational Therapists' Experiences in Conducting Home Assessments and Modifications: Virtual Versus In-person Home Visits...American Congress of Rehabilitation Medicine (ACRM) 99th Annual Conference, November 8-11, 2022, Chicago, Illinois

To investigate occupational therapists' experiences with home assessments and modifications in VHA, while comparing virtual to in-person home visits. A preliminary qualitative study using semi-structured individual interviews. Department of Veterans Affairs (VA) Home Based Primary Care (HBPC). Purposefully selected occupational therapists implementing home assessments and modifications for rural Veterans (N=3). Not applicable. Semi-structured individual interview via Microsoft Teams. Home visits to conduct home assessments and modifications for rural Veterans were standards of care delivery. However, travel restrictions and social distance during the COVID-19 pandemic required a shift toward virtual care. Our preliminary results show that the VA Video Connect (VVC) application allows occupational therapists to provide instant feedback and training to Veterans when new equipment is installed in the Veteran's home, without the need to drive long-distance. However, the VVC does not allow occupational therapists to measure physical features of the home, such as door threshold height and hallway width. Participants also reported difficulty evaluating Veterans' functioning, such as balance, strength, and gait pattern. Thus, the VVC improves access to the services but requires additional assistance from caregivers compared to in-home assessments. Initial home assessments are recommended to be conducted during home visits, but follow-up visits can be conducted via telehealth depending on Veterans' and caregivers' ability to utilize telehealth devices and perform self-assessments. The study team has no conflicts of interest to report.

Occupational Therapists' Experiences in Conducting Home Assessments and Modifications: Virtual Versus In-person Home Visits

To investigate occupational therapists' experiences with home assessments and modifications in VHA, while comparing virtual to in-person home visits. A preliminary qualitative study using semi-structured individual interviews. Department of Veterans Affairs (VA) Home Based Primary Care (HBPC). Purposefully selected occupational therapists implementing home assessments and modifications for rural Veterans (N=3). Not applicable. Semi-structured individual interview via Microsoft Teams. Home visits to conduct home assessments and modifications for rural Veterans were standards of care delivery. However, travel restrictions and social distance during the COVID-19 pandemic required a shift toward virtual care. Our preliminary results show that the VA Video Connect (VVC) application allows occupational therapists to provide instant feedback and training to Veterans when new equipment is installed in the Veteran's home, without the need to drive long-distance. However, the VVC does not allow occupational therapists to measure physical features of the home, such as door threshold height and hallway width. Participants also reported difficulty evaluating Veterans' functioning, such as balance, strength, and gait pattern. Thus, the VVC improves access to the services but requires additional assistance from caregivers compared to in-home assessments. Initial home assessments are recommended to be conducted during home visits, but follow-up visits can be conducted via telehealth depending on Veterans' and caregivers' ability to utilize telehealth devices and perform self-assessments. The study team has no conflicts of interest to report.

BNT162b2 induces robust cross-variant SARS-CoV-2 immunity in children.

Currently available mRNA vaccines are extremely safe and effective to prevent severe SARS-CoV-2 infections. However, the emergence of variants of concerns (VOCs) has highlighted the importance of high population-based vaccine rates to effectively suppress viral transmission and breakthrough infections. While initially left out from vaccine efforts, children have become one of the most affected age groups and are key targets to stop community and household spread. Antibodies are central for vaccine-induced protection and emerging data points to the importance of additional Fc effector functions like opsononophagocytosis or cytotoxicity, particularly in the context of VOCs that escape neutralizing antibodies. Here, we observed delayed induction and reduced magnitude of vaccine-induced antibody titers in children 5-11 years receiving two doses of the age-recommended 10 µg dose of the Pfizer SARS-CoV-2 BNT162b2 vaccine compared to adolescents (12-15 years) or adults receiving the 30 µg dose. Conversely, children mounted equivalent or more robust neutralization and opsonophagocytic functions at peak immunogenicity, pointing to a qualitatively more robust humoral functional response in children. Moreover, broad cross-VOC responses were observed across children, with enhanced IgM and parallel IgG cross-reactivity to VOCs in children compared to adults. Collectively, these data argue that despite the lower magnitude of the BNT162b2-induced antibody response in children, vaccine-induced immunity in children target VOCs broadly and exhibit enhanced functionality that may contribute to the attenuation of disease.

Nucleocapsid-specific antibody function is associated with therapeutic benefits from COVID-19 convalescent plasma therapy.

Coronavirus disease 2019 (COVID-19) convalescent plasma (CCP), a passive polyclonal antibody therapeutic agent, has had mixed clinical results. Although antibody neutralization is the predominant approach to benchmarking CCP efficacy, CCP may also influence the evolution of the endogenous antibody response. Using systems serology to comprehensively profile severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) functional antibodies of hospitalized people with COVID-19 enrolled in a randomized controlled trial of CCP (ClinicalTrials.gov: NCT04397757), we find that the clinical benefits of CCP are associated with a shift toward reduced inflammatory Spike (S) responses and enhanced nucleocapsid (N) humoral responses. We find that CCP has the greatest clinical benefit in participants with low pre-existing anti-SARS-CoV-2 antibody function and that CCP-induced immunomodulatory Fc glycan profiles and N immunodominant profiles persist for at least 2 months. We highlight a potential mechanism of action of CCP associated with durable immunomodulation, outline optimal patient characteristics for CCP treatment, and provide guidance for development of a different class of COVID-19 hyperinflammation-targeting antibody therapeutic agents.

SARS-CoV-2 mRNA vaccination elicits robust antibody responses in children.

Although children have been largely spared from coronavirus disease 2019 (COVID-19), the emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern (VOCs) with increased transmissibility, combined with fluctuating mask mandates and school reopenings, has led to increased infections and disease among children. Thus, there is an urgent need to roll out COVID-19 vaccines to children of all ages. However, whether children respond equivalently to adults to mRNA vaccines and whether dosing will elicit optimal immunity remain unclear. Here, we aimed to deeply profile the vaccine-induced humoral immune response in 6- to 11-year-old children receiving either a pediatric (50 µg) or adult (100 µg) dose of the mRNA-1273 vaccine and to compare these responses to vaccinated adults, infected children, and children who experienced multisystem inflammatory syndrome in children (MIS-C). Children elicited an IgG-dominant vaccine-induced immune response, surpassing adults at a matched 100-µg dose but more variable immunity at a 50-µg dose. Irrespective of titer, children generated antibodies with enhanced Fc receptor binding capacity. Moreover, like adults, children generated cross-VOC humoral immunity, marked by a decline of omicron-specific receptor binding domain, but robustly preserved omicron spike protein binding. Fc receptor binding capabilities were also preserved in a dose-dependent manner. These data indicate that both the 50- and 100-µg doses of mRNA vaccination in children elicit robust cross-VOC antibody responses and that 100-µg doses in children result in highly preserved omicron-specific functional humoral immunity.

Preserved recognition of Omicron spike following COVID-19 messenger RNA vaccination in pregnancy.

BACKGROUND: SARS-CoV-2 infection is associated with enhanced disease severity in pregnant women. Despite the potential of COVID-19 vaccines to reduce severe disease, vaccine uptake remained relatively low among pregnant women. Just as coordinated messaging from the Centers for Disease Control and Prevention and leading obstetrics organizations began to increase vaccine confidence in this vulnerable group, the evolution of SARS-CoV-2 variants of concerns, including the Omicron variant, raised new concerns about vaccine efficacy because of their ability to escape vaccine-induced neutralizing antibodies. Early data point to a milder disease course following infection with the Omicron variant in vaccinated individuals. Thus, these data suggest that alternate vaccine-induced immunity beyond neutralization may continue to attenuate Omicron variant-induced disease, such as Fc-mediated antibody activity. OBJECTIVE: This study aimed to test whether vaccine-induced antibodies raised during pregnancy continue to bind to and leverage Fc receptors to protect against variants of concern including the Omicron variant. STUDY DESIGN: The receptor binding domain or whole spike-specific antibody isotype binding titers and Fc gamma receptor binding directed toward variants of concern, including the Omicron variant, were analyzed in pregnant women after receiving the full dose regimen of either the Pfizer/BioNTech BNT62b2 (n=10) or Moderna mRNA-1273 (n=10) vaccination using a multiplexing Luminex assay. RESULTS: Reduced isotype recognition of the Omicron receptor binding domain was observed following administration of either vaccine with relatively preserved, albeit reduced, recognition of the whole Omicron spike by immunoglobulin M and G antibodies. Despite the near complete loss of Fc receptor binding to the Omicron receptor binding domain, Fc receptor binding to the Omicron spike was more variable but largely preserved. CONCLUSION: Reduced binding titers to the Omicron receptor binding domain aligns with the observed loss of neutralizing activity. Despite the loss of neutralization, preserved, albeit reduced, Omicron spike recognition and Fc receptor binding potentially continue to attenuate disease severity in pregnant women.

Omicron variant Spike-specific antibody binding and Fc activity are preserved in recipients of mRNA or inactivated COVID-19 vaccines.

The Omicron variant of SARS-CoV-2 has been shown to evade neutralizing antibodies elicited by vaccination or infection. Despite the global spread of the Omicron variant, even among highly vaccinated populations, death rates have not increased concomitantly. These data suggest that immune mechanisms beyond antibody-mediated virus neutralization may protect against severe disease. In addition to neutralizing pathogens, antibodies contribute to control and clearance of infections through Fc effector mechanisms. Here, we probed the ability of vaccine-induced antibodies to drive Fc effector activity against the Omicron variant using samples from individuals receiving one of three SARS-CoV-2 vaccines. Despite a substantial loss of IgM, IgA, and IgG binding to the Omicron variant receptor binding domain (RBD) in samples from individuals receiving BNT162b2, mRNA-1273, and CoronaVac vaccines, stable binding was maintained against the full-length Omicron Spike protein. Compromised RBD binding IgG was accompanied by a loss of RBD-specific antibody Fcγ receptor (FcγR) binding in samples from individuals who received the CoronaVac vaccine, but RBD-specific FcγR2a and FcγR3a binding was preserved in recipients of mRNA vaccines. Conversely, Spike protein-specific antibodies exhibited persistent but reduced binding to FcγRs across all three vaccines, although higher binding was observed in samples from recipients of mRNA vaccines. This was associated with preservation of FcγR2a and FcγR3a binding antibodies and maintenance of Spike protein-specific antibody-dependent natural killer cell activation. Thus, despite the loss of Omicron neutralization, vaccine-induced Spike protein-specific antibodies continue to drive Fc effector functions, suggesting a capacity for extraneutralizing antibodies to contribute to disease control.

mRNA-1273 vaccine-induced antibodies maintain Fc effector functions across SARS-CoV-2 variants of concern.

SARS-CoV-2 mRNA vaccines confer robust protection against COVID-19, but the emergence of variants has generated concerns regarding the protective efficacy of the currently approved vaccines, which lose neutralizing potency against some variants. Emerging data suggest that antibody functions beyond neutralization may contribute to protection from the disease, but little is known about SARS-CoV-2 antibody effector functions. Here, we profiled the binding and functional capacity of convalescent antibodies and Moderna mRNA-1273 COVID-19 vaccine-induced antibodies across SARS-CoV-2 variants of concern (VOCs). Although the neutralizing responses to VOCs decreased in both groups, the Fc-mediated responses were distinct. In convalescent individuals, although antibodies exhibited robust binding to VOCs, they showed compromised interactions with Fc-receptors. Conversely, vaccine-induced antibodies also bound robustly to VOCs but continued to interact with Fc-receptors and mediate antibody effector functions. These data point to a resilience in the mRNA-vaccine-induced humoral immune response that may continue to offer protection from SARS-CoV-2 VOCs independent of neutralization.

Early cross-coronavirus reactive signatures of humoral immunity against COVID-19.

The introduction of vaccines has inspired hope in the battle against SARS-CoV-2. However, the emergence of viral variants, in the absence of potent antivirals, has left the world struggling with the uncertain nature of this disease. Antibodies currently represent the strongest correlate of immunity against SARS-CoV-2, thus we profiled the earliest humoral signatures in a large cohort of acutely ill (survivors and nonsurvivors) and mild or asymptomatic individuals with COVID-19. Although a SARS-CoV-2­specific immune response evolved rapidly in survivors of COVID-19, nonsurvivors exhibited blunted and delayed humoral immune evolution, particularly with respect to S2-specific antibodies. Given the conservation of S2 across ß-coronaviruses, we found that the early development of SARS-CoV-2­specific immunity occurred in tandem with preexisting common ß-coronavirus OC43 humoral immunity in survivors, which was also selectively expanded in individuals that develop a paucisymptomatic infection. These data point to the importance of cross-coronavirus immunity as a correlate of protection against COVID-19.

Humoral signatures of protective and pathological SARS-CoV-2 infection in children.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic continues to spread relentlessly, associated with a high frequency of respiratory failure and mortality. Children experience largely asymptomatic disease, with rare reports of multisystem inflammatory syndrome in children (MIS-C). Identifying immune mechanisms that result in these disparate clinical phenotypes in children could provide critical insights into coronavirus disease 2019 (COVID-19) pathogenesis. Using systems serology, in this study we observed in 25 children with acute mild COVID-19 a functional phagocyte and complement-activating IgG response to SARS-CoV-2, similar to the acute responses generated in adults with mild disease. Conversely, IgA and neutrophil responses were significantly expanded in adults with severe disease. Moreover, weeks after the resolution of SARS-CoV-2 infection, children who develop MIS-C maintained highly inflammatory monocyte-activating SARS-CoV-2 IgG antibodies, distinguishable from acute disease in children but with antibody levels similar to those in convalescent adults. Collectively, these data provide unique insights into the potential mechanisms of IgG and IgA that might underlie differential disease severity as well as unexpected complications in children infected with SARS-CoV-2.

Discrete SARS-CoV-2 antibody titers track with functional humoral stability.

Antibodies serve as biomarkers of infection, but if sustained can confer long-term immunity. Yet, for most clinically approved vaccines, binding antibody titers only serve as a surrogate of protection. Instead, the ability of vaccine induced antibodies to neutralize or mediate Fc-effector functions is mechanistically linked to protection. While evidence has begun to point to persisting antibody responses among SARS-CoV-2 infected individuals, cases of re-infection have begun to emerge, calling the protective nature of humoral immunity against this highly infectious pathogen into question. Using a community-based surveillance study, we aimed to define the relationship between titers and functional antibody activity to SARS-CoV-2 over time. Here we report significant heterogeneity, but limited decay, across antibody titers amongst 120 identified seroconverters, most of whom had asymptomatic infection. Notably, neutralization, Fc-function, and SARS-CoV-2 specific T cell responses were only observed in subjects that elicited RBD-specific antibody titers above a threshold. The findings point to a switch-like relationship between observed antibody titer and function, where a distinct threshold of activity-defined by the level of antibodies-is required to elicit vigorous humoral and cellular response. This response activity level may be essential for durable protection, potentially explaining why re-infections occur with SARS-CoV-2 and other common coronaviruses.