Heterologous versus homologous boosting elicits qualitatively distinct, BA.5-cross-reactive T cells in transplant recipients.

BackgroundThe SARS-CoV-2 Omicron BA.5 subvariant escapes vaccination-induced neutralizing antibodies because of mutations in the spike (S) protein. Solid organ transplant recipients (SOTRs) develop high COVID-19 morbidity and poor Omicron variant recognition after COVID-19 vaccination. T cell responses may provide a second line of defense. Therefore, understanding which vaccine regimens induce robust, conserved T cell responses is critical.MethodsWe evaluated anti-S IgG titers, subvariant pseudo-neutralization, and S-specific CD4+ and CD8+ T cell responses from SOTRs in a national, prospective, observational trial (n = 75). Participants were selected if they received 3 doses of mRNA (homologous boosting) or 2 doses of mRNA followed by Ad26.COV2.S (heterologous boosting).ResultsHomologous boosting with 3 mRNA doses induced the highest anti-S IgG titers. However, antibodies induced by both vaccine regimens demonstrated lower pseudo-neutralization against BA.5 compared with the ancestral strain. In contrast, vaccine-induced S-specific T cells maintained cross-reactivity against BA.5 compared with ancestral recognition. Homologous boosting induced higher frequencies of activated polyfunctional CD4+ T cell responses, with polyfunctional IL-21+ peripheral T follicular helper cells increased in mRNA-1273 compared with BNT162b2. IL-21+ cells correlated with antibody titers. Heterologous boosting with Ad26.COV2.S did not increase CD8+ responses compared to homologous boosting.ConclusionBoosting with the ancestral strain can induce cross-reactive T cell responses against emerging variants in SOTRs, but alternative vaccine strategies are required to induce robust CD8+ T cell responses.FundingBen-Dov Family; NIH National Institute of Allergy and Infectious Diseases (NIAID) K24AI144954, NIAID K08AI156021, NIAID K23AI157893, NIAID U01AI138897, National Institute of Diabetes and Digestive and Kidney Diseases T32DK007713, and National Cancer Institute 1U54CA260492; Johns Hopkins Vice Dean of Research Support for COVID-19 Research in Immunopathogenesis; and Emory COVID-19 research repository.

Persistent SARS-CoV-2-specific immune defects in kidney transplant recipients following third mRNA vaccine dose.

Kidney transplant recipients (KTRs) show poorer response to SARS-CoV-2 mRNA vaccination, yet response patterns and mechanistic drivers following third doses are ill-defined. We administered third monovalent mRNA vaccines to n = 81 KTRs with negative or low-titer anti-receptor binding domain (RBD) antibody (n = 39 anti-RBDNEG; n = 42 anti-RBDLO), compared with healthy controls (HCs, n = 19), measuring anti-RBD, Omicron neutralization, spike-specific CD8+%, and SARS-CoV-2-reactive T cell receptor (TCR) repertoires. By day 30, 44% anti-RBDNEG remained seronegative; 5% KTRs developed BA.5 neutralization (vs 68% HCs, P < .001). Day 30 spike-specific CD8+% was negative in 91% KTRs (vs 20% HCs; P = .07), without correlation to anti-RBD (rs = 0.17). Day 30 SARS-CoV-2-reactive TCR repertoires were detected in 52% KTRs vs 74% HCs (P = .11). Spike-specific CD4+ TCR expansion was similar between KTRs and HCs, yet KTR CD8+ TCR depth was 7.6-fold lower (P = .001). Global negative response was seen in 7% KTRs, associated with high-dose MMF (P = .037); 44% showed global positive response. Of the KTRs, 16% experienced breakthrough infections, with 2 hospitalizations; prebreakthrough variant neutralization was poor. Absent neutralizing and CD8+ responses in KTRs indicate vulnerability to COVID-19 despite 3-dose mRNA vaccination. Lack of neutralization despite CD4+ expansion suggests B cell dysfunction and/or ineffective T cell help. Development of more effective KTR vaccine strategies is critical. (NCT04969263).

Anti-PF4 antibodies associated with disease severity in COVID-19.

Severe COVID-19 is characterized by a prothrombotic state associated with thrombocytopenia, with microvascular thrombosis being almost invariably present in the lung and other organs at postmortem examination. We evaluated the presence of antibodies to platelet factor 4 (PF4)-polyanion complexes using a clinically validated immunoassay in 100 hospitalized patients with COVID-19 with moderate or severe disease (World Health Organization score, 4 to 10), 25 patients with acute COVID-19 visiting the emergency department, and 65 convalescent individuals. Anti-PF4 antibodies were detected in 95 of 100 hospitalized patients with COVID-19 (95.0%) irrespective of prior heparin treatment, with a mean optical density value of 0.871 ± 0.405 SD (range, 0.177 to 2.706). In contrast, patients hospitalized for severe acute respiratory disease unrelated to COVID-19 had markedly lower levels of the antibodies. In a high proportion of patients with COVID-19, levels of all three immunoglobulin (Ig) isotypes tested (IgG, IgM, and IgA) were simultaneously elevated. Antibody levels were higher in male than in female patients and higher in African Americans and Hispanics than in White patients. Anti-PF4 antibody levels were correlated with the maximum disease severity score and with significant reductions in circulating platelet counts during hospitalization. In individuals convalescent from COVID-19, the antibody levels returned to near-normal values. Sera from patients with COVID-19 induced higher levels of platelet activation than did sera from healthy blood donors, but the results were not correlated with the levels of anti-PF4 antibodies. These results demonstrate that the vast majority of patients with severe COVID-19 develop anti-PF4 antibodies, which may play a role in the clinical complications of COVID-19.

Point-of-Care Lung Ultrasound Predicts Severe Disease and Death Due to COVID-19: A Prospective Cohort Study.

The clinical utility of point-of-care lung ultrasound (LUS) among hospitalized patients with COVID-19 is unclear. DESIGN: Prospective cohort study. SETTING: A large tertiary care center in Maryland, between April 2020 and September 2021. PATIENTS: Hospitalized adults (≥ 18 yr old) with positive severe acute respiratory syndrome coronavirus 2 reverse transcriptase-polymerase chain reaction results. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: All patients were scanned using a standardized protocol including 12 lung zones and followed to determine clinical outcomes until hospital discharge and vital status at 28 days. Ultrasounds were independently reviewed for lung and pleural line artifacts and abnormalities, and the mean LUS Score (mLUSS) (ranging from 0 to 3) across lung zones was determined. The primary outcome was time to ICU-level care, defined as high-flow oxygen, noninvasive, or invasive mechanical ventilation, within 28 days of the initial ultrasound. Cox proportional hazards regression models adjusted for age and sex were fit for mLUSS and each ultrasound covariate. A total of 264 participants were enrolled in the study; the median age was 61 years and 114 participants (43.2%) were female. The median mLUSS was 1.0 (interquartile range, 0.5-1.3). Following enrollment, 27 participants (10.0%) went on to require ICU-level care, and 14 (5.3%) subsequently died by 28 days. Each increase in mLUSS at enrollment was associated with disease progression to ICU-level care (adjusted hazard ratio [aHR], 3.61; 95% CI, 1.27-10.2) and 28-day mortality (aHR, 3.10; 95% CI, 1.29-7.50). Pleural line abnormalities were independently associated with disease progression to death (aHR, 20.93; CI, 3.33-131.30). CONCLUSIONS: Participants with a mLUSS greater than or equal to 1 or pleural line changes on LUS had an increased likelihood of subsequent requirement of high-flow oxygen or greater. LUS is a promising tool for assessing risk of COVID-19 progression at the bedside.

Impact of Seasonal Coronavirus Antibodies on SARS-CoV-2 Vaccine Responses in Solid Organ Transplant Recipients.

Antibody responses to SARS-CoV-2 vaccination are reduced in solid organ transplant recipients (SOTRs). We report that increased levels of pre-existing antibodies to seasonal coronaviruses are associated with decreased antibody response to SARS-CoV-2 vaccination in SOTRs, supporting that antigenic imprinting modulates vaccine responses in this immunosuppressed population.

Endemic Human Coronavirus Antibody Levels Are Unchanged after Convalescent or Control Plasma Transfusion for Early Outpatient COVID-19 Treatment.

The impact of preexisting antibodies to the four endemic human coronaviruses (ehCoV) (229E, OC43, NL63, and HKU1) on severe (hospitalization) coronavirus disease 2019 (COVID-19) outcomes has been described in small cohorts. Many studies have measured ehCoV 229E, OC43, NL63, and HKU1 antibody levels weeks after recovery rather than in the first weeks of illness, which is more relevant to early hospitalizations. Antibody levels to the spike protein of the four coronaviruses (229E, OC43, NL63, and HKU1), as well as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), were measured both before and immediately after convalescent or control plasma transfusion in 51 participants who were hospitalized and 250 who were not hospitalized, as well as in 71 convalescent and 50 control plasma donors as a subset from a completed randomized controlled trial. In COVID-19 convalescent plasma donors, the ehCoV spike antibodies were 1.2 to 2 times greater than the control donor unit levels, while donor COVID-19 convalescent plasma (CCP) SARS-CoV-2 spike antibodies were more than 600 times the control plasma units. Plasma transfusion, whether COVID-19 convalescent or control, did not alter the post-transfusion antibody levels for the endemic human coronaviruses (229E, OC43, NL63, and HKU1) in those hospitalized and not hospitalized, despite the 1.2- to 2-fold elevation in donor COVID-19 convalescent plasma. There was no influence of prior antibody levels to 229E, OC43, NL63, and HKU1 or post-transfusion antibody levels on subsequent hospitalization. These data, from a well-controlled prospective randomized clinical trial, add evidence that antibodies to ehCoV do not significantly impact COVID-19 outcomes, despite the apparent back-boosting of some ehCoV after SARS-CoV-2 infection. IMPORTANCE The relevance of preexisting immunity to the four endemic human coronaviruses in the first week of COVID-19 illness on the outcome of COVID-19 progression stems from the high prevalence of the ehCoV and SARS-CoV-2 coronaviruses. The question has been raised of whether therapeutic convalescent plasma or control plasma containing ehCoV antibodies might alter the outcome of COVID-19 progression to hospitalization. Here, we observed that plasma transfusion did not significantly change the preexisting ehCoV antibody levels. In over 50 hospitalized participants and 250 nonhospitalized participants, ehCoV antibody levels were comparable, without statistical differences. Antibody levels were stable over the more than 12 months of the intervention trial, with individual heterogeneity similar in hospitalized and nonhospitalized participants. The ehCoV antibodies in plasma transfusion did not alter the recipient preexisting antibody levels nor hasten the COVID-19 progression to hospitalization in this clinical trial data.

Reconsideration of Antinucleocapsid IgG Antibody as a Marker of SARS-CoV-2 Infection Postvaccination for Mild COVID-19 Patients.

Antinucleocapsid (anti-N) immunoglobulin G antibody responses were lower in plasma and oral fluid after severe acute respiratory syndrome coronavirus 2 infection in vaccinated patients compared with patients infected before vaccination or infected without vaccination. This raises questions about the long-term use of anti-N antibodies as a marker for natural infection for surveillance.

Discordant Antibody and T-Cell Responses to the Severe Acute Respiratory Syndrome Coronavirus 2 Omicron Variant in Coronavirus Disease 2019 Messenger RNA Vaccine Recipients.

We compared antibody and T-cell responses against the severe acute respiratory syndrome coronavirus 2 vaccine strain spike protein to responses against the Omicron variant in 15 messenger RNA vaccine recipients. While these individuals had significantly lower levels of antibodies that inhibited Omicron spike protein binding to ACE2, there was no difference in T-cell responses.

Unbiased discovery of autoantibodies associated with severe COVID-19 via genome-scale self-assembled DNA-barcoded protein libraries.

Pathogenic autoreactive antibodies that may be associated with life-threatening coronavirus disease 2019 (COVID-19) remain to be identified. Here, we show that self-assembled genome-scale libraries of full-length proteins covalently coupled to unique DNA barcodes for analysis by sequencing can be used for the unbiased identification of autoreactive antibodies in plasma samples. By screening 11,076 DNA-barcoded proteins expressed from a sequence-verified human ORFeome library, the method, which we named MIPSA (for Molecular Indexing of Proteins by Self-Assembly), allowed us to detect circulating neutralizing type-I and type-III interferon (IFN) autoantibodies in five plasma samples from 55 patients with life-threatening COVID-19. In addition to identifying neutralizing type-I IFN-α and IFN-ω autoantibodies and other previously known autoreactive antibodies in patient plasma, MIPSA enabled the detection of as yet unidentified neutralizing type-III anti-IFN-λ3 autoantibodies that were not seen in healthy plasma samples or in convalescent plasma from ten non-hospitalized individuals with COVID-19. The low cost and simple workflow of MIPSA will facilitate unbiased high-throughput analyses of protein-antibody, protein-protein and protein-small-molecule interactions.

Point-of-Care Lung Ultrasound Predicts Severe Disease and Death Due to COVID-19: A Prospective Cohort Study

OBJECTIVES: The clinical utility of point-of-care lung ultrasound (LUS) among hospitalized patients with COVID-19 is unclear. DESIGN: Prospective cohort study. SETTING: A large tertiary care center in Maryland, between April 2020 and September 2021. PATIENTS: Hospitalized adults (≥ 18 yr old) with positive severe acute respiratory syndrome coronavirus 2 reverse transcriptase-polymerase chain reaction results. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: All patients were scanned using a standardized protocol including 12 lung zones and followed to determine clinical outcomes until hospital discharge and vital status at 28 days. Ultrasounds were independently reviewed for lung and pleural line artifacts and abnormalities, and the mean LUS Score (mLUSS) (ranging from 0 to 3) across lung zones was determined. The primary outcome was time to ICU-level care, defined as high-flow oxygen, noninvasive, or invasive mechanical ventilation, within 28 days of the initial ultrasound. Cox proportional hazards regression models adjusted for age and sex were fit for mLUSS and each ultrasound covariate. A total of 264 participants were enrolled in the study;the median age was 61 years and 114 participants (43.2%) were female. The median mLUSS was 1.0 (interquartile range, 0.5–1.3). Following enrollment, 27 participants (10.0%) went on to require ICU-level care, and 14 (5.3%) subsequently died by 28 days. Each increase in mLUSS at enrollment was associated with disease progression to ICU-level care (adjusted hazard ratio [aHR], 3.61;95% CI, 1.27–10.2) and 28-day mortality (aHR, 3.10;95% CI, 1.29–7.50). Pleural line abnormalities were independently associated with disease progression to death (aHR, 20.93;CI, 3.33–131.30). CONCLUSIONS: Participants with a mLUSS greater than or equal to 1 or pleural line changes on LUS had an increased likelihood of subsequent requirement of high-flow oxygen or greater. LUS is a promising tool for assessing risk of COVID-19 progression at the bedside.

Decay of coronavirus disease 2019 mRNA vaccine-induced immunity in people with HIV.

Current coronavirus disease 2019 (COVID-19) mRNA vaccines induce robust SARS-CoV-2-specific humoral and cellular responses in people with HIV (PWH). However, the rate of decay of effector immune responses has not been studied in these individuals. Here, we report a significant waning of antibody responses but persistent T-cell responses 6 months post vaccination in virally suppressed PWH with high CD4+ T-cell counts. These responses are comparable with those seen in healthy donors.

Markers of endothelial cell activation are associated with the severity of pulmonary disease in COVID-19.

Severe coronavirus disease-19 (COVID-19) is characterized by vascular inflammation and thrombosis. We and others have proposed that the inflammatory response to coronavirus infection activates endothelial cells, leading to endothelial release of pro-thrombotic proteins. These mediators can trigger obstruction of the pulmonary microvasculature, leading to worsening oxygenation, acute respiratory distress syndrome, and death. In the current study, we tested the hypothesis that higher levels of biomarkers released from endothelial cells are associated with worse oxygenation in patients with COVID-19. We studied 83 participants aged 18-84 years with COVID-19 admitted to a single center. The severity of pulmonary disease was classified by oxygen requirement, including no oxygen requirement, low-flow oxygen, high-flow nasal cannula oxygen, mechanical ventilation, and death. We measured plasma levels of two proteins released by activated endothelial cells, von Willebrand Factor (VWF) antigen and soluble P-Selectin (sP-Sel), and a biomarker of systemic thrombosis, D-dimer. Additionally, we explored the association of endothelial biomarker levels with the levels of pro-inflammatory cytokine and chemokines, and vascular inflammation biomarkers. We found that levels of VWF, sP-sel, and D-dimer were increased in individuals with more severe COVID-19 pulmonary disease. Biomarkers of endothelial cell activation were also correlated with proinflammatory cytokines and chemokines. Taken together, our data demonstrate increased levels of VWF and sP-selectin are linked to the severity of lung disease in COVID-19 and correlated with biomarkers of inflammation and vascular inflammation. Our data support the concept that COVID-19 is a vascular disease which involves endothelial injury in the context of an inflammatory state.

SARS-CoV-2 vaccination diversifies the CD4+ spike-reactive T cell repertoire in patients with prior SARS-CoV-2 infection.

BACKGROUND: COVID-19 mRNA vaccines elicit strong T and B cell responses to the SARS-CoV-2 spike glycoprotein in both SARS-CoV-2 naïve and experienced patients. However, it is unknown whether the post-vaccine CD4+ T cell responses seen in patients with a history of COVID-19 are due to restimulation of T cell clonotypes that were first activated during natural infection or if they are the result of new clones activated by the vaccine. METHODS: To address this question, we analyzed the SARS-CoV-2 spike glycoprotein-specific CD4+ T cell receptor repertoire before and after vaccination in 10 COVID-19 convalescent patients and 4 SARS-CoV-2 naïve healthy donor vaccine recipients. We used the viral Functional Expansion of Specific T cells (ViraFEST) assay to quantitatively identify specific SARS-CoV-2 and common cold coronavirus CD4+ T cell clonotypes post COVID-19 disease resolution and post mRNA SARS-CoV-2 vaccination. FINDINGS: We found that while some preexisting T cell receptor clonotypes persisted, the post-vaccine repertoire consisted mainly of vaccine-induced clones and was largely distinct from the repertoire induced by natural infection. Vaccination-induced clones led to an overall maintenance of the total number of SARS-CoV-2 reactive clonotypes over time through expansion of novel clonotypes only stimulated through vaccination. Additionally, we demonstrated that the vaccine preferentially induces T cells that are only specific for SARS-CoV-2 antigens, rather than T cells that cross-recognize SARS-CoV-2/common cold coronaviruses. INTERPRETATION: These data demonstrate that SARS-CoV-2 vaccination in patients with prior SARS-CoV-2 infection induces a new antigen-specific repertoire and sheds light on the differential immune responses induced by vaccination versus natural infection. FUNDING: Bloomberg∼Kimmel Institute for Cancer Immunotherapy, The Johns Hopkins University, The Bill and Melinda Gates Foundation, NCI U54CA260492, NIH.

A Fourth Dose of COVID-19 Vaccine Does Not Induce Neutralization of the Omicron Variant Among Solid Organ Transplant Recipients With Suboptimal Vaccine Response.

BACKGROUND: Humoral responses to coronavirus disease 2019 (COVID-19) vaccines are attenuated in solid organ transplant recipients (SOTRs), necessitating additional booster vaccinations. The Omicron variant demonstrates substantial immune evasion, and it is unknown whether additional vaccine doses increase neutralizing capacity versus this variant of concern (VOC) among SOTRs. METHODS: Within an observational cohort, 25 SOTRs with low seroresponse underwent anti-severe acute respiratory syndrome coronavirus 2 spike and receptor-binding domain immunoglobulin (Ig)G testing using a commercially available multiplex ELISA before and after a fourth COVID-19 vaccine dose (D4). Surrogate neutralization (percent angiotensin-converting enzyme 2 inhibition [%ACE2i], range 0%-100% with >20% correlating with live virus neutralization) was measured against full-length spike proteins of the vaccine strain and 5 VOCs including Delta and Omicron. Changes in IgG level and %ACE2i were compared using the paired Wilcoxon signed-rank test. RESULTS: Anti-receptor-binding domain and anti-spike seropositivity increased post-D4 from 56% to 84% and 68% to 88%, respectively. Median (interquartile range) anti-spike antibody significantly increased post-D4 from 42.3 (4.9-134.2) to 228.9 (1115.4-655.8) World Health Organization binding antibody units. %ACE2i (median [interquartile range]) also significantly increased against the vaccine strain (5.8% [0%-16.8%] to 20.6% [5.8%-45.9%]) and the Delta variant (9.1% [4.9%-12.8%] to 17.1% [10.3%-31.7%]), yet neutralization versus Omicron was poor, did not increase post-D4 (4.1% [0%-6.9%] to 0.5% [0%-5.7%]), and was significantly lower than boosted healthy controls. CONCLUSIONS: Although a fourth vaccine dose increases anti-spike IgG and neutralizing capacity against many VOCs, some SOTRs may remain at high risk for Omicron infection despite boosting. Thus, additional protective interventions or alternative vaccination strategies should be urgently explored.

SARS-CoV-2-specific immune responses in boosted vaccine recipients with breakthrough infections during the Omicron variant surge.

BackgroundBreakthrough SARS-CoV-2 infections in vaccinated individuals have been previously associated with suboptimal humoral immunity. However, less is known about breakthrough infections with the Omicron variant.MethodsWe analyzed SARS-CoV-2-specific antibody and cellular responses in healthy vaccine recipients who experienced breakthrough infections a median of 50 days after receiving a booster mRNA vaccine with an ACE2 binding inhibition assay and an ELISpot assay, respectively.ResultsWe found that high levels of antibodies inhibited vaccine strain spike protein binding to ACE2 but that lower levels inhibited Omicron variant spike protein binding to ACE2 in 4 boosted vaccine recipients prior to infection. The levels of antibodies that inhibited vaccine strain and Omicron spike protein binding after breakthrough in 18 boosted vaccine recipients were similar to levels seen in COVID-19-negative boosted vaccine recipients. In contrast, boosted vaccine recipients had significantly stronger T cell responses to both vaccine strain and Omicron variant spike proteins at the time of breakthrough.ConclusionOur data suggest that breakthrough infections with the Omicron variant can occur despite robust immune responses to the vaccine strain spike protein.FundingThis work was supported by the Johns Hopkins COVID-19 Vaccine-related Research Fund and by funds from the National Institute of Allergy and Infectious Disease intramural program as well as awards from the National Cancer Institute (U54CA260491) and the National Institutes of Allergy and Infectious Disease (K08AI156021 and U01AI138897).

IgM anti-ACE2 autoantibodies in severe COVID-19 activate complement and perturb vascular endothelial function.

BackgroundSome clinical features of severe COVID-19 represent blood vessel damage induced by activation of host immune responses initiated by the coronavirus SARS-CoV-2. We hypothesized autoantibodies against angiotensin-converting enzyme 2 (ACE2), the SARS-CoV-2 receptor expressed on vascular endothelium, are generated during COVID-19 and are of mechanistic importance.MethodsIn an opportunity sample of 118 COVID-19 inpatients, autoantibodies recognizing ACE2 were detected by ELISA. Binding properties of anti-ACE2 IgM were analyzed via biolayer interferometry. Effects of anti-ACE2 IgM on complement activation and endothelial function were demonstrated in a tissue-engineered pulmonary microvessel model.ResultsAnti-ACE2 IgM (not IgG) autoantibodies were associated with severe COVID-19 and found in 18/66 (27.2%) patients with severe disease compared with 2/52 (3.8%) of patients with moderate disease (OR 9.38, 95% CI 2.38-42.0; P = 0.0009). Anti-ACE2 IgM autoantibodies were rare (2/50) in non-COVID-19 ventilated patients with acute respiratory distress syndrome. Unexpectedly, ACE2-reactive IgM autoantibodies in COVID-19 did not undergo class-switching to IgG and had apparent KD values of 5.6-21.7 nM, indicating they are T cell independent. Anti-ACE2 IgMs activated complement and initiated complement-binding and functional changes in endothelial cells in microvessels, suggesting they contribute to the angiocentric pathology of COVID-19.ConclusionWe identify anti-ACE2 IgM as a mechanism-based biomarker strongly associated with severe clinical outcomes in SARS-CoV-2 infection, which has therapeutic implications.FUNDINGBill & Melinda Gates Foundation, Gates Philanthropy Partners, Donald B. and Dorothy L. Stabler Foundation, and Jerome L. Greene Foundation; NIH R01 AR073208, R01 AR069569, Institutional Research and Academic Career Development Award (5K12GM123914-03), National Heart, Lung, and Blood Institute R21HL145216, and Division of Intramural Research, National Institute of Allergy and Infectious Diseases; National Science Foundation Graduate Research Fellowship (DGE1746891).

Differentiation of Individuals Previously Infected with and Vaccinated for SARS-CoV-2 in an Inner-City Emergency Department.

Emergency departments (EDs) can serve as surveillance sites for infectious diseases. The objective of this study was to determine the burden of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and to monitor the prevalence of vaccination against coronavirus disease 2019 (COVID-19) among patients attending an urban ED in Baltimore City. Using 1,914 samples of known exposure status, we developed an algorithm to differentiate previously infected, vaccinated, and unexposed individuals using a combination of antibody assays. We applied this testing algorithm to 4,360 samples from ED patients obtained in the spring of 2020 and 2021. Using multinomial logistic regression, we determined factors associated with infection and vaccination. For the algorithm, sensitivity and specificity for identifying vaccinated individuals were 100% and 99%, respectively, and 84% and 100% for previously infected individuals. Among the ED subjects, seroprevalence to SARS-CoV-2 increased from 2% to 24% between April 2020 and March 2021. Vaccination prevalence rose to 11% by mid-March 2021. Marked differences in burden of disease and vaccination coverage were seen by sex, race, and ethnicity. Hispanic patients, though accounting for 7% of the study population, had the highest relative burden of disease (17% of total infections) but with similar vaccination rates. Women and white individuals were more likely to be vaccinated than men or Black individuals. Individuals previously infected with SARS-CoV-2 can often be differentiated from vaccinated individuals using a serologic testing algorithm. The utility of this algorithm can aid in monitoring SARS-CoV-2 exposure and vaccination uptake frequencies and can potentially reflect gender, race, and ethnic health disparities.

Continued Virus-Specific Antibody-Secreting Cell Production, Avidity Maturation and B Cell Evolution in Patients Hospitalized with COVID-19.

Understanding the development and sustainability of the virus-specific protective immune response to infection with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) remains incomplete with respect to the appearance and disappearance of virus-specific antibody-secreting cells (ASCs) in circulation. Therefore, we performed cross-sectional and longitudinal analyses of peripheral blood mononuclear cells and plasma collected from 55 hospitalized patients up to 4 months after onset of COVID-19 symptoms. Spike (S)- and nucleocapsid (N)-specific IgM and IgG ASCs appeared within 2 weeks accompanied by flow cytometry increases in double negative plasmablasts consistent with a rapid extrafollicular B cell response. Total and virus-specific IgM and IgG ASCs peaked at 3-4 weeks and were still being produced at 3-4 months accompanied by increasing antibody avidity consistent with a slower germinal center B cell response. N-specific ASCs were produced for longer than S-specific ASCs and avidity maturation was greater for antibody to N than S. Patients with more severe disease produced more S-specific IgM and IgG ASCs than those with mild disease and had higher levels of N- and S-specific antibody. Women had more B cells in circulation than men and produced more S-specific IgA and IgG and N-specific IgG ASCs. Flow cytometry analysis of B cell phenotypes showed an increase in circulating B cells at 4-6 weeks with decreased percentages of switched and unswitched memory B cells. These data indicate ongoing antigen-specific stimulation, maturation, and production of ASCs for several months after onset of symptoms in patients hospitalized with COVID-19.

The BNT162b2 mRNA Vaccine Elicits Robust Humoral and Cellular Immune Responses in People Living With Human Immunodeficiency Virus (HIV).

Previous studies have shown that certain vaccines induce suboptimal responses in people living with human immunodeficiency virus (HIV, PLWH). However, responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines have not been fully characterized in these patients. Here we show that the BNT162b2 vaccine induces robust immune responses comparable to responses in healthy donors.