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.

COVID-19 Therapeutics and Considerations for Pregnancy.

The COVID-19 pandemic has generated an unprecedented amount of novel and repurposed vaccines and therapeutics that have been rapidly developed and implemented into clinical use. Unfortunately, pregnant persons have been excluded from most phase III clinical studies; therefore, our understanding regarding their safety for use in this population stems from understanding of theoretic risks and observational data. In this review, the authors discuss pregnancy-specific considerations for COVID-19 therapeutics.

Pan-neutralizing, germline-encoded antibodies against SARS-CoV-2: Addressing the long-term problem of escape variants.

Despite the initially reported high efficacy of vaccines directed against ancestral SARS-CoV-2, repeated infections in both unvaccinated and vaccinated populations remain a major global health challenge. Because of mutation-mediated immune escape by variants-of-concern (VOC), approved neutralizing antibodies (neutAbs) effective against the original strains have been rendered non-protective. Identification and characterization of mutation-independent pan-neutralizing antibody responses are therefore essential for controlling the pandemic. Here, we characterize and discuss the origins of SARS-CoV-2 neutAbs, arising from either natural infection or following vaccination. In our study, neutAbs in COVID-19 patients were detected using the combination of two lateral flow immunoassay (LFIA) tests, corroborated by plaque reduction neutralization testing (PRNT). A point-of-care neutAb LFIA, NeutraXpress™, was validated using serum samples from historical pre-COVID-19 negative controls, patients infected with other respiratory pathogens, and PCR-confirmed COVID-19 patients. Surprisingly, potent neutAb activity was mainly noted in patients generating both IgM and IgG against the Spike receptor-binding domain (RBD), in contrast to samples possessing anti-RBD IgG alone. We propose that low-affinity, high-avidity, germline-encoded natural IgM and subsequent generation of class-switched IgG may have an underappreciated role in cross-protection, potentially offsetting immune escape by SARS-CoV-2 variants. We suggest Reverse Vaccinology 3.0 to further exploit this innate-like defense mechanism. Our proposition has potential implications for immunogen design, and provides strategies to elicit pan-neutAbs from natural B1-like cells. Refinements in future immunization protocols might further boost long-term cross-protection, even at the mucosal level, against clinical manifestations of COVID-19.

High-Dose Inhaled Nitric Oxide for the Treatment of Spontaneously Breathing Pregnant Patients With Severe Coronavirus Disease 2019 (COVID-19) Pneumonia.

OBJECTIVE: To evaluate whether the use of inhaled nitric oxide (iNO)200 improves respiratory function. METHODS: This retrospective cohort study used data from pregnant patients hospitalized with severe bilateral coronavirus disease 2019 (COVID-19) pneumonia at four teaching hospitals between March 2020 and December 2021. Two cohorts were identified: 1) those receiving standard of care alone (SoC cohort) and 2) those receiving iNO200 for 30 minutes twice daily in addition to standard of care alone (iNO200 cohort). Inhaled nitric oxide, as a novel therapy, was offered only at one hospital. The prespecified primary outcome was days free from any oxygen supplementation at 28 days postadmission. Secondary outcomes were hospital length of stay, rate of intubation, and intensive care unit (ICU) length of stay. The multivariable-adjusted regression analyses accounted for age, body mass index, gestational age, use of steroids, remdesivir, and the study center. RESULTS: Seventy-one pregnant patients were hospitalized for severe bilateral COVID-19 pneumonia: 51 in the SoC cohort and 20 in the iNO200 cohort. Patients receiving iNO200 had more oxygen supplementation-free days (iNO200: median [interquartile range], 24 [23-26] days vs standard of care alone: 22 [14-24] days, P=.01) compared with patients in the SoC cohort. In the multivariable-adjusted analyses, iNO200 was associated with 63.2% (95% CI 36.2-95.4%; P<.001) more days free from oxygen supplementation, 59.7% (95% CI 56.0-63.2%; P<.001) shorter ICU length of stay, and 63.6% (95% CI 55.1-70.8%; P<.001) shorter hospital length of stay. No iNO200-related adverse events were reported. CONCLUSION: In pregnant patients with severe bilateral COVID-19 pneumonia, iNO200 was associated with a reduced need for oxygen supplementation and shorter hospital stay.

Durability of Heterologous and Homologous COVID-19 Vaccine Boosts.

Importance: Antibody responses elicited by current messenger RNA (mRNA) COVID-19 vaccines decline rapidly and require repeated boosting. Objective: To evaluate the immunogenicity and durability of heterologous and homologous prime-boost regimens involving the adenovirus vector vaccine Ad26.COV2.S and the mRNA vaccine BNT162b2. Design, Setting, and Participants: In this cohort study at a single clinical site in Boston, Massachusetts, 68 individuals who were vaccinated at least 6 months previously with 2 immunizations of BNT162b2 were boosted with either Ad26.COV2.S or BNT162b2. Enrollment of participants occurred from August 12, 2021, to October 25, 2021, and this study involved 4 months of follow-up. Data analysis was performed from November 2021 to February 2022. Exposures: Participants who were previously vaccinated with BNT162b2 received a boost with either Ad26.COV2.S or BNT162b2. Main Outcomes and Measures: Humoral immune responses were assessed by neutralizing, binding, and functional antibody responses for 16 weeks following the boost. CD8+ and CD4+ T-cell responses were evaluated by intracellular cytokine staining assays. Results: Among 68 participants who were originally vaccinated with BNT162b2 and boosted with Ad26.COV2.S (41 participants; median [range] age, 36 [23-84] years) or BNT162b2 (27 participants; median [range] age, 35 [23-76] years), 56 participants (82%) were female, 7 (10%) were Asian, 4 (6%) were Black, 4 (6%) were Hispanic or Latino, 3 (4%) were more than 1 race, and 53 (78%) were White. Both vaccines were found to be associated with increased humoral and cellular immune responses, including against SARS-CoV-2 variants of concern. BNT162b2 boosting was associated with a rapid increase of Omicron neutralizing antibodies that peaked at a median (IQR) titer of 1018 (699-1646) at week 2 and declined by 6.9-fold to a median (IQR) titer of 148 (95-266) by week 16. Ad26.COV2.S boosting was associated with increased Omicron neutralizing antibodies titers that peaked at a median (IQR) of 859 (467-1838) week 4 and declined by 2.1-fold to a median (IQR) of 403 (208-1130) by week 16. Conclusions and Relevance: Heterologous Ad26.COV2.S boosting was associated with durable humoral and cellular immune responses in individuals who originally received the BNT162b2 vaccine. These data suggest potential benefits of heterologous prime-boost vaccine regimens for SARS-CoV-2.

Characterization of immune responses in fully vaccinated individuals after breakthrough infection with the SARS-CoV-2 delta variant.

Breakthrough infections with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants have been reported frequently in vaccinated individuals with waning immunity. In particular, a cluster of over 1000 infections with the SARS-CoV-2 delta variant was identified in a predominantly fully vaccinated population in Provincetown, Massachusetts in July 2021. In this study, vaccinated individuals who tested positive for SARS-CoV-2 (n = 16) demonstrated substantially higher serum antibody responses than vaccinated individuals who tested negative for SARS-CoV-2 (n = 23), including 32-fold higher binding antibody titers and 31-fold higher neutralizing antibody titers against the SARS-CoV-2 delta variant. Vaccinated individuals who tested positive also showed higher mucosal antibody responses in nasal secretions and higher spike protein-specific CD8+ T cell responses in peripheral blood than did vaccinated individuals who tested negative. These data demonstrate that fully vaccinated individuals developed robust anamnestic antibody and T cell responses after infection with the SARS-CoV-2 delta variant. Moreover, these findings suggest that population immunity will likely increase over time by a combination of widespread vaccination and breakthrough infections.

Coronavirus Disease 2019 Messenger RNA Vaccine Immunogenicity in Immunosuppressed Individuals.

Individuals on immunosuppressive (IS) therapy have increased mortality from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, and delayed viral clearance may lead to new viral variants. IS therapy reduces antibody responses following coronavirus disease 2019 (COVID-19) messenger RNA (mRNA) vaccination; however, a comprehensive assessment of vaccine immunogenicity is lacking. Here we show that IS therapy reduced neutralizing, binding, and nonneutralizing antibody functions in addition to CD4 and CD8 T-cell interferon-γ responses following COVID-19 mRNA vaccination compared to immunocompetent individuals. Moreover, IS therapy reduced cross-reactivity against SARS-CoV-2 variants. These data suggest that the standard COVID-19 mRNA vaccine regimens will likely not provide optimal protection in immunocompromised individuals.

Vaccines elicit highly conserved cellular immunity to SARS-CoV-2 Omicron.

The highly mutated SARS-CoV-2 Omicron (B.1.1.529) variant has been shown to evade a substantial fraction of neutralizing antibody responses elicited by current vaccines that encode the WA1/2020 spike protein1. Cellular immune responses, particularly CD8+ T cell responses, probably contribute to protection against severe SARS-CoV-2 infection2-6. Here we show that cellular immunity induced by current vaccines against SARS-CoV-2 is highly conserved to the SARS-CoV-2 Omicron spike protein. Individuals who received the Ad26.COV2.S or BNT162b2 vaccines demonstrated durable spike-specific CD8+ and CD4+ T cell responses, which showed extensive cross-reactivity against both the Delta and the Omicron variants, including in central and effector memory cellular subpopulations. Median Omicron spike-specific CD8+ T cell responses were 82-84% of the WA1/2020 spike-specific CD8+ T cell responses. These data provide immunological context for the observation that current vaccines still show robust protection against severe disease with the SARS-CoV-2 Omicron variant despite the substantially reduced neutralizing antibody responses7,8.

Compassionate Use of Remdesivir in Pregnant Women With Severe Coronavirus Disease 2019.

BACKGROUND: Remdesivir is efficacious for severe coronavirus disease 2019 (COVID-19) in adults, but data in pregnant women are limited. We describe outcomes in the first 86 pregnant women with severe COVID-19 who were treated with remdesivir. METHODS: The reported data span 21 March to 16 June 2020 for hospitalized pregnant women with polymerase chain reaction-confirmed severe acute respiratory syndrome coronavirus 2 infection and room air oxygen saturation ≤94% whose clinicians requested remdesivir through the compassionate use program. The intended remdesivir treatment course was 10 days (200 mg on day 1, followed by 100 mg for days 2-10, given intravenously). RESULTS: Nineteen of 86 women delivered before their first dose and were reclassified as immediate "postpartum" (median postpartum day 1 [range, 0-3]). At baseline, 40% of pregnant women (median gestational age, 28 weeks) required invasive ventilation, in contrast to 95% of postpartum women (median gestational age at delivery 30 weeks). By day 28 of follow-up, the level of oxygen requirement decreased in 96% and 89% of pregnant and postpartum women, respectively. Among pregnant women, 93% of those on mechanical ventilation were extubated, 93% recovered, and 90% were discharged. Among postpartum women, 89% were extubated, 89% recovered, and 84% were discharged. Remdesivir was well tolerated, with a low incidence of serious adverse events (AEs) (16%). Most AEs were related to pregnancy and underlying disease; most laboratory abnormalities were grade 1 or 2. There was 1 maternal death attributed to underlying disease and no neonatal deaths. CONCLUSIONS: Among 86 pregnant and postpartum women with severe COVID-19 who received compassionate-use remdesivir, recovery rates were high, with a low rate of serious AEs.

Correlates of Neutralization against SARS-CoV-2 Variants of Concern by Early Pandemic Sera.

Emerging SARS-CoV-2 variants of concern that overcome natural and vaccine-induced immunity threaten to exacerbate the COVID-19 pandemic. Increasing evidence suggests that neutralizing antibody (NAb) responses are a primary mechanism of protection against infection. However, little is known about the extent and mechanisms by which natural immunity acquired during the early COVID-19 pandemic confers cross-neutralization of emerging variants. In this study, we investigated cross-neutralization of the B.1.1.7 and B.1.351 SARS-CoV-2 variants in a well-characterized cohort of early pandemic convalescent subjects. We observed modestly decreased cross-neutralization of B.1.1.7 but a substantial 4.8-fold reduction in cross-neutralization of B.1.351. Correlates of cross-neutralization included receptor binding domain (RBD) and N-terminal domain (NTD) binding antibodies, homologous NAb titers, and membrane-directed T cell responses. These data shed light on the cross-neutralization of emerging variants by early pandemic convalescent immune responses. IMPORTANCE Widespread immunity to SARS-CoV-2 will be necessary to end the COVID-19 pandemic. NAb responses are a critical component of immunity that can be stimulated by natural infection as well as vaccines. However, SARS-CoV-2 variants are emerging that contain mutations in the spike gene that promote evasion from NAb responses. These variants may therefore delay control of the COVID-19 pandemic. We studied whether NAb responses from early COVID-19 convalescent patients are effective against the two SARS-CoV-2 variants, B.1.1.7 and B.1.351. We observed that the B.1.351 variant demonstrates significantly reduced susceptibility to early pandemic NAb responses. We additionally characterized virological, immunological, and clinical features that correlate with cross-neutralization. These studies increase our understanding of emerging SARS-CoV-2 variants.

Selective functional antibody transfer into the breastmilk after SARS-CoV-2 infection.

Antibody transfer via breastmilk represents an evolutionary strategy to boost immunity in early life. Although severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific antibodies have been observed in the breastmilk, the functional quality of these antibodies remains unclear. Here, we apply systems serology to characterize SARS-CoV-2-specific antibodies in maternal serum and breastmilk to compare the functional characteristics of antibodies in these fluids. Distinct SARS-CoV-2-specific antibody responses are observed in the serum and breastmilk of lactating individuals previously infected with SARS-CoV-2, with a more dominant transfer of immunoglobulin A (IgA) and IgM into breastmilk. Although IgGs are present in breastmilk, they are functionally attenuated. We observe preferential transfer of antibodies capable of eliciting neutrophil phagocytosis and neutralization compared to other functions, pointing to selective transfer of certain functional antibodies to breastmilk. These data highlight the preferential transfer of SARS-CoV-2-specific IgA and IgM to breastmilk, accompanied by select IgG subpopulations, positioned to create a non-pathologic but protective barrier against coronavirus disease 2019 (COVID-19).

Tie2 activation protects against prothrombotic endothelial dysfunction in COVID-19.

Endothelial dysfunction accompanies the microvascular thrombosis commonly observed in severe COVID-19. Constitutively, the endothelial surface is anticoagulant, a property maintained at least in part via signaling through the Tie2 receptor. During inflammation, the Tie2 antagonist angiopoietin-2 (Angpt-2) is released from endothelial cells and inhibits Tie2, promoting a prothrombotic phenotypic shift. We sought to assess whether severe COVID-19 is associated with procoagulant endothelial dysfunction and alterations in the Tie2/angiopoietin axis. Primary HUVECs treated with plasma from patients with severe COVID-19 upregulated the expression of thromboinflammatory genes, inhibited the expression of antithrombotic genes, and promoted coagulation on the endothelial surface. Pharmacologic activation of Tie2 with the small molecule AKB-9778 reversed the prothrombotic state induced by COVID-19 plasma in primary endothelial cells. Lung autopsies from patients with COVID-19 demonstrated a prothrombotic endothelial signature. Assessment of circulating endothelial markers in a cohort of 98 patients with mild, moderate, or severe COVID-19 revealed endothelial dysfunction indicative of a prothrombotic state. Angpt-2 concentrations rose with increasing disease severity, and the highest levels were associated with worse survival. These data highlight the disruption of Tie2/angiopoietin signaling and procoagulant changes in endothelial cells in severe COVID-19. Our findings provide rationale for current trials of Tie2-activating therapy with AKB-9778 in COVID-19.

Immunogenicity of COVID-19 mRNA Vaccines in Pregnant and Lactating Women.

Importance: Pregnant women are at increased risk of morbidity and mortality from COVID-19 but have been excluded from the phase 3 COVID-19 vaccine trials. Data on vaccine safety and immunogenicity in these populations are therefore limited. Objective: To evaluate the immunogenicity of COVID-19 messenger RNA (mRNA) vaccines in pregnant and lactating women, including against emerging SARS-CoV-2 variants of concern. Design, Setting, and Participants: An exploratory, descriptive, prospective cohort study enrolled 103 women who received a COVID-19 vaccine from December 2020 through March 2021 and 28 women who had confirmed SARS-CoV-2 infection from April 2020 through March 2021 (the last follow-up date was March 26, 2021). This study enrolled 30 pregnant, 16 lactating, and 57 neither pregnant nor lactating women who received either the mRNA-1273 (Moderna) or BNT162b2 (Pfizer-BioNTech) COVID-19 vaccines and 22 pregnant and 6 nonpregnant unvaccinated women with SARS-CoV-2 infection. Main Outcomes and Measures: SARS-CoV-2 receptor binding domain binding, neutralizing, and functional nonneutralizing antibody responses from pregnant, lactating, and nonpregnant women were assessed following vaccination. Spike-specific T-cell responses were evaluated using IFN-γ enzyme-linked immunospot and multiparameter intracellular cytokine-staining assays. Humoral and cellular immune responses were determined against the original SARS-CoV-2 USA-WA1/2020 strain as well as against the B.1.1.7 and B.1.351 variants. Results: This study enrolled 103 women aged 18 to 45 years (66% non-Hispanic White) who received a COVID-19 mRNA vaccine. After the second vaccine dose, fever was reported in 4 pregnant women (14%; SD, 6%), 7 lactating women (44%; SD, 12%), and 27 nonpregnant women (52%; SD, 7%). Binding, neutralizing, and functional nonneutralizing antibody responses as well as CD4 and CD8 T-cell responses were present in pregnant, lactating, and nonpregnant women following vaccination. Binding and neutralizing antibodies were also observed in infant cord blood and breast milk. Binding and neutralizing antibody titers against the SARS-CoV-2 B.1.1.7 and B.1.351 variants of concern were reduced, but T-cell responses were preserved against viral variants. Conclusion and Relevance: In this exploratory analysis of a convenience sample, receipt of a COVID-19 mRNA vaccine was immunogenic in pregnant women, and vaccine-elicited antibodies were transported to infant cord blood and breast milk. Pregnant and nonpregnant women who were vaccinated developed cross-reactive antibody responses and T-cell responses against SARS-CoV-2 variants of concern.