A third SARS-CoV-2 mRNA vaccine dose in people receiving hemodialysis overcomes B cell defects but elicits a skewed CD4+ T cell profile.

Cellular immune defects associated with suboptimal responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mRNA vaccination in people receiving hemodialysis (HD) are poorly understood. We longitudinally analyze antibody, B cell, CD4+, and CD8+ T cell vaccine responses in 27 HD patients and 26 low-risk control individuals (CIs). The first two doses elicit weaker B cell and CD8+ T cell responses in HD than in CI, while CD4+ T cell responses are quantitatively similar. In HD, a third dose robustly boosts B cell responses, leads to convergent CD8+ T cell responses, and enhances comparatively more T helper (TH) immunity. Unsupervised clustering of single-cell features reveals phenotypic and functional shifts over time and between cohorts. The third dose attenuates some features of TH cells in HD (tumor necrosis factor alpha [TNFα]/interleukin [IL]-2 skewing), while others (CCR6, CXCR6, programmed cell death protein 1 [PD-1], and HLA-DR overexpression) persist. Therefore, a third vaccine dose is critical to achieving robust multifaceted immunity in hemodialysis patients, although some distinct TH characteristics endure.

Spike recognition and neutralization of SARS-CoV-2 Omicron subvariants elicited after the third dose of mRNA vaccine.

Several severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron subvariants have recently emerged, becoming the dominant circulating strains in many countries. These variants contain a large number of mutations in their spike glycoprotein, raising concerns about vaccine efficacy. In this study, we evaluate the ability of plasma from a cohort of individuals that received three doses of mRNA vaccine to recognize and neutralize these Omicron subvariant spikes. We observed that BA.4/5 and BQ.1.1 spikes are markedly less recognized and neutralized compared with the D614G and other Omicron subvariant spikes tested. Also, individuals who have been infected before or after vaccination present better humoral responses than SARS-CoV-2-naive vaccinated individuals, thus indicating that hybrid immunity generates better humoral responses against these subvariants.

Molecular basis for antiviral activity of two pediatric neutralizing antibodies targeting SARS-CoV-2 Spike RBD.

Neutralizing antibodies (NAbs) hold great promise for clinical interventions against SARS-CoV-2 variants of concern (VOCs). Understanding NAb epitope-dependent antiviral mechanisms is crucial for developing vaccines and therapeutics against VOCs. Here we characterized two potent NAbs, EH3 and EH8, isolated from an unvaccinated pediatric patient with exceptional plasma neutralization activity. EH3 and EH8 cross-neutralize the early VOCs and mediate strong Fc-dependent effector activity in vitro. Structural analyses of EH3 and EH8 in complex with the receptor-binding domain (RBD) revealed the molecular determinants of the epitope-driven protection and VOC evasion. While EH3 represents the prevalent IGHV3-53 NAb whose epitope substantially overlaps with the ACE2 binding site, EH8 recognizes a narrow epitope exposed in both RBD-up and RBD-down conformations. When tested in vivo, a single-dose prophylactic administration of EH3 fully protected stringent K18-hACE2 mice from lethal challenge with Delta VOC. Our study demonstrates that protective NAbs responses converge in pediatric and adult SARS-CoV-2 patients.

A boost with SARS-CoV-2 BNT162b2 mRNA vaccine elicits strong humoral responses independently of the interval between the first two doses.

Due to the recrudescence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections worldwide, mainly caused by the Omicron variant of concern (VOC) and its sub-lineages, several jurisdictions are administering an mRNA vaccine boost. Here, we analyze humoral responses induced after the second and third doses of an mRNA vaccine in naive and previously infected donors who received their second dose with an extended 16-week interval. We observe that the extended interval elicits robust humoral responses against VOCs, but this response is significantly diminished 4 months after the second dose. Administering a boost to these individuals brings back the humoral responses to the same levels obtained after the extended second dose. Interestingly, we observe that administering a boost to individuals that initially received a short 3- to 4-week regimen elicits humoral responses similar to those observed in the long interval regimen. Nevertheless, humoral responses elicited by the boost in naive individuals do not reach those present in previously infected vaccinated individuals.

A boost with SARS-CoV-2 BNT162b2 mRNA vaccine elicits strong humoral responses independently of the interval between the first two doses

Due to the recrudescence of SARS-CoV-2 infections worldwide, mainly caused by Omicron variant of concern (VOC) and its sub-lineages, several jurisdictions are administering a mRNA vaccine boost. Here, we analyze humoral responses induced after the second and third doses of mRNA vaccine in naïve and previously-infected donors who received their second dose with an extended 16-week interval. We observe that the extended interval elicits robust humoral responses against VOCs, but this response is significantly diminished 4 months after the second dose. Administering a boost to these individuals brings back the humoral responses to the same levels obtained after the extended second dose. Interestingly, we observe that administering a boost to individuals that initially received a short 3-4 weeks regimen elicits humoral responses similar to those observed in the long interval regimen. Nevertheless, humoral responses elicited by the boost in naïve individuals do not reach those present in previously-infected vaccinated individuals. Graphical In this study, Tauzin et al. report that the third dose of SARS-CoV-2 mRNA vaccine elicits strong humoral responses against VOCs in naïve individuals, regardless of the interval between the first two doses. However, these responses remain lower than those induced by hybrid immunity.

Humoral immune responses against SARS-CoV-2 Spike variants after mRNA vaccination in solid organ transplant recipients.

Although SARS-CoV-2 mRNA vaccination has been shown to be safe and effective in the general population, immunocompromised solid organ transplant recipients (SOTRs) were reported to have impaired immune responses after one or two doses of vaccine. In this study, we examined humoral responses induced after the second and the third dose of mRNA vaccine in different SOTR (kidney, liver, lung, and heart). Compared to a cohort of SARS-CoV-2 naïve immunocompetent health care workers (HCWs), the second dose induced weak humoral responses in SOTRs, except for the liver recipients. The third dose boosted these responses but they did not reach the same level as in HCW. Interestingly, although the neutralizing activity against Delta and Omicron variants remained very low after the third dose, Fc-mediated effector functions in SOTR reached similar levels as in the HCW cohort. Whether these responses will suffice to protect SOTR from severe outcome remains to be determined.

COVID-19 vaccine humoral response in frequent platelet donors with plateletpheresis-associated lymphopenia.

BACKGROUND: Plateletpheresis involves platelet separation and collection from whole blood while other blood cells are returned to the donor. Because platelets are replaced faster than red blood cells, as many as 24 donations can be done annually. However, some frequent apheresis platelet donors (>20 donations annually) display severe plateletpheresis-associated lymphopenia; in particular, CD4+ T but not B cell numbers are decreased. COVID-19 vaccination thereby provides a model to assess whether lymphopenic platelet donors present compromised humoral immune responses. STUDY DESIGN AND METHODS: We assessed vaccine responses following 2 doses of COVID-19 vaccination in a cohort of 43 plateletpheresis donors with a range of pre-vaccination CD4+ T cell counts (76-1537 cells/µl). In addition to baseline T cell measurements, antibody binding assays to full-length Spike and the Receptor Binding Domain (RBD) were performed pre- and post-vaccination. Furthermore, pseudo-particle neutralization and antibody-dependent cellular cytotoxicity assays were conducted to measure antibody functionality. RESULTS: Participants were stratified into two groups: <400 CD4/µl (n = 27) and ≥ 400 CD4/µl (n = 16). Following the first dose, 79% seroconverted within the <400 CD4/µl group compared to 87% in the ≥400 CD4/µl group; all donors were seropositive post-second dose with significant increases in antibody levels. Importantly differences in CD4+ T cell levels minimally impacted neutralization, Spike recognition, and IgG Fc-mediated effector functions. DISCUSSION: Overall, our results indicate that lymphopenic plateletpheresis donors do not exhibit significant immune dysfunction; they have retained the T and B cell functionality necessary for potent antibody responses after vaccination.

SARS-CoV-2 Omicron Spike recognition by plasma from individuals receiving BNT162b2 mRNA vaccination with a 16-week interval between doses.

Continuous emergence of SARS-CoV-2 variants of concern (VOCs) is fueling the COVID-19 pandemic. Omicron (B.1.1.529) rapidly spread worldwide. The large number of mutations in its Spike raise concerns about a major antigenic drift that could significantly decrease vaccine efficacy and infection-induced immunity. A long interval between BNT162b2 mRNA doses elicits antibodies that efficiently recognize Spikes from different VOCs. Here, we evaluate the recognition of Omicron Spike by plasma from a cohort of SARS-CoV-2 naive and previously infected individuals who received their BNT162b2 mRNA vaccine 16 weeks apart. Omicron Spike is recognized less efficiently than D614G, Alpha, Beta, Gamma, and Delta Spikes. We compare with plasma activity from participants receiving a short (4 weeks) interval regimen. Plasma from individuals of the long-interval cohort recognize and neutralize better the Omicron Spike compared with those who received a short interval. Whether this difference confers any clinical benefit against Omicron remains unknown.

A Fc-enhanced NTD-binding non-neutralizing antibody delays virus spread and synergizes with a nAb to protect mice from lethal SARS-CoV-2 infection.

Emerging evidence indicates that both neutralizing and Fc-mediated effector functions of antibodies contribute to protection against SARS-CoV-2. It is unclear whether Fc-effector functions alone can protect against SARS-CoV-2. Here, we isolated CV3-13, a non-neutralizing antibody, from a convalescent individual with potent Fc-mediated effector functions. The cryoelectron microscopy structure of CV3-13 in complex with the SARS-CoV-2 spike reveals that the antibody binds from a distinct angle of approach to an N-terminal domain (NTD) epitope that only partially overlaps with the NTD supersite recognized by neutralizing antibodies. CV3-13 does not alter the replication dynamics of SARS-CoV-2 in K18-hACE2 mice, but its Fc-enhanced version significantly delays virus spread, neuroinvasion, and death in prophylactic settings. Interestingly, the combination of Fc-enhanced non-neutralizing CV3-13 with Fc-compromised neutralizing CV3-25 completely protects mice from lethal SARS-CoV-2 infection. Altogether, our data demonstrate that efficient Fc-mediated effector functions can potently contribute to the in vivo efficacy of anti-SARS-CoV-2 antibodies.

Antigenicity of the Mu (B.1.621) and A.2.5 SARS-CoV-2 Spikes.

The rapid emergence of SARS-CoV-2 variants is fueling the recent waves of the COVID-19 pandemic. Here, we assessed ACE2 binding and antigenicity of Mu (B.1.621) and A.2.5 Spikes. Both these variants carry some mutations shared by other emerging variants. Some of the pivotal mutations such as N501Y and E484K in the receptor-binding domain (RBD) detected in B.1.1.7 (Alpha), B.1.351 (Beta) and P.1 (Gamma) are now present within the Mu variant. Similarly, the L452R mutation of B.1.617.2 (Delta) variant is present in A.2.5. In this study, we observed that these Spike variants bound better to the ACE2 receptor in a temperature-dependent manner. Pseudoviral particles bearing the Spike of Mu were similarly neutralized by plasma from vaccinated individuals than those carrying the Beta (B.1.351) and Delta (B.1.617.2) Spikes. Altogether, our results indicate the importance of measuring critical parameters such as ACE2 interaction, plasma recognition and neutralization ability of each emerging variant.

Strong humoral immune responses against SARS-CoV-2 Spike after BNT162b2 mRNA vaccination with a 16-week interval between doses.

The standard regimen of the BNT162b2 mRNA vaccine for SARS-CoV-2 includes two doses administered three weeks apart. However, some public health authorities spaced these doses, raising questions about efficacy. We analyzed longitudinal humoral responses against the D614G strain and variants of concern for SARS-CoV-2 in a cohort of SARS-CoV-2-naive and previously infected individuals who received the BNT162b2 mRNA vaccine with sixteen weeks between doses. While administering a second dose to previously infected individuals did not significantly improve humoral responses, these responses significantly increased in naive individuals after a 16-week spaced second dose, achieving similar levels as in previously infected individuals. Comparing these responses to those elicited in individuals receiving a short (4-week) dose interval showed that a 16-week interval induced more robust responses among naive vaccinees. These findings suggest that a longer interval between vaccine doses does not compromise efficacy and may allow greater flexibility in vaccine administration.

Contribution of single mutations to selected SARS-CoV-2 emerging variants spike antigenicity.

Towards the end of 2020, multiple variants of concern (VOCs) and variants of interest (VOIs) have arisen from the original SARS-CoV-2 Wuhan-Hu-1 strain. Mutations in the Spike protein are highly scrutinized for their impact on transmissibility, pathogenesis and vaccine efficacy. Here, we contribute to the growing body of literature on emerging variants by evaluating the impact of single mutations on the overall antigenicity of selected variants and their binding to the ACE2 receptor. We observe a differential contribution of single mutants to the global variants phenotype related to ACE2 interaction and antigenicity. Using biolayer interferometry, we observe that enhanced ACE2 interaction is mostly modulated by a decrease in off-rate. Finally, we made the interesting observation that the Spikes from tested emerging variants bind better to ACE2 at 37°C compared to the D614G variant. Whether improved ACE2 binding at higher temperature facilitates emerging variants transmission remain to be demonstrated.

Short-term antibody response after 1 dose of BNT162b2 vaccine in patients receiving hemodialysis.

BACKGROUND: Patients receiving in-centre hemodialysis are at high risk of exposure to SARS-CoV-2 and death if infected. One dose of the BNT162b2 SARS-CoV-2 vaccine is efficacious in the general population, but responses in patients receiving hemodialysis are uncertain. METHODS: We obtained serial plasma from patients receiving hemodialysis and health care worker controls before and after vaccination with 1 dose of the BNT162b2 mRNA vaccine, as well as convalescent plasma from patients receiving hemodialysis who survived COVID-19. We measured anti-receptor binding domain (RBD) immunoglobulin G (IgG) levels and stratified groups by evidence of previous SARS-CoV-2 infection. RESULTS: Our study included 154 patients receiving hemodialysis (135 without and 19 with previous SARS-CoV-2 infection), 40 controls (20 without and 20 with previous SARS-CoV-2 infection) and convalescent plasma from 16 patients. Among those without previous SARS-CoV-2 infection, anti-RBD IgG was undetectable at 4 weeks in 75 of 131 (57%, 95% confidence interval [CI] 47% to 65%) patients receiving hemodialysis, compared with 1 of 20 (5%, 95% CI 1% to 23%) controls (p < 0.001). No patient with nondetectable levels at 4 weeks developed anti-RBD IgG by 8 weeks. Results were similar in non-immunosuppressed and younger individuals. Three patients receiving hemodialysis developed severe COVID-19 after vaccination. Among those with previous SARS-CoV-2 infection, median anti-RBD IgG levels at 8 weeks in patients receiving hemodialysis were similar to controls at 3 weeks (p = 0.3) and to convalescent plasma (p = 0.8). INTERPRETATION: A single dose of BNT162b2 vaccine failed to elicit a humoral immune response in most patients receiving hemodialysis without previous SARS-CoV-2 infection, even after prolonged observation. In those with previous SARS-CoV-2 infection, the antibody response was delayed. We advise that patients receiving hemodialysis be prioritized for a second BNT162b2 dose at the recommended 3-week interval.

Short-term antibody response and tolerability of one dose of BNT162b2 vaccine in patients receiving hemodialysis (preprint)

BackgroundPatients receiving in-center hemodialysis (HD) are at high risk of exposure to SARS-CoV-2 with high mortality, and response to vaccination is uncertain. MethodsWe obtained serial plasma from 58 HD patients and 32 health-care workers (HCW) before and after vaccination with one dose of the BNT162b2 mRNA vaccine; as well as convalescent plasma from 11 HD patients who survived COVID-19. Anti-RBD (region binding domain of the SARS-CoV-2 Spike protein) IgG and IgM levels were measured by ELISA. Groups were stratified by evidence of prior SARS-CoV-2 infection. ResultsIn HD patients without prior SARS-CoV-2, antiRBD levels were significantly lower at 4 and 8 weeks after vaccination, compared to in HCWs after 3 weeks (p<0.001), and to convalescent plasma (p=0.002). Anti-RBD IgG was non-detectable in 29/46 (63%) of HD, compared to 1/16 (6%) of HCWs (p<0.0001). No patient with non-detectable levels at 4 weeks developed antiRBD by 8 weeks. In HD patients with prior SARS-CoV-2, mean 8-week anti-RBD IgG levels were similar to controls at 3 weeks (p=0.16), and to convalescent plasma (p=0.45). No patients reported symptoms 7 days after vaccination on a standardized questionnaire. InterpretationWhile the BNT162b2 vaccine was well-tolerated in hemodialysis patients, a single dose failed to elicit a humoral immune response in the majority of SARS-CoV-2 naive patients even after prolonged observation. In those with prior SARS-CoV-2 infection, the humoral response after vaccination was delayed. Whether HD patients develop T-cell responses requires further study. Until then, we advise the second dose be administered to all HD patients at the recommended 3-week time interval, and that rigorous SARS-CoV-2 infection prevention and control measures be continued in dialysis units until vaccine efficacy is proven.