SARS-CoV-2 vaccine response and rate of breakthrough infection in patients with hematological disorders

Inactivated vaccine dosage and serum IgG levels correlate with persistent COVID-19 infections in hematologic malignancy patients during the Omicron Surge in China

PURPOSE

The essence of this scholarly work was to carefully outline the key factors intensifying the virulence and protracted contagion of COVID-19, particularly among individuals afflicted with hematologic malignancies (HM), in an epoch predominantly governed by the Omicron variant.

METHODS

Adults with HM diagnosed with COVID-19 from November 2022 to February 2023 were monitored in this retrospective study. Patient blood samples yielded biochemical data, and COVID-19 was confirmed through RNA or antigen testing. The factors affecting severity and infection duration were examined using both univariate and multivariate logistic regression analyses. For calculating the overall survival probabilities, the Kaplan-Meier product limit approach was employed.

RESULTS

In the examined cohort, 133 individuals diagnosed with HM and concomitantly infected with COVID-19 were scrutinized. Of the participants, 29.3% (39 patients) were classified as Severe/Critical, while the other 70.7% (94 patients) were categorized as Non-severe. A significant difference was observed in vaccination status: 61.7% of patients in the Non-severe group had received at least a two-dose vaccine regimen, whereas 61.5% of the Severe/Critical group had either minimal or only one dose of vaccination. The data analysis revealed that elevated C-reactive protein levels (≥ 100 mg/L) significantly raised the risk of severe/critical conditions in HM patients with COVID-19, as determined by advanced multivariate logistic regression. The odds ratio was 3.415 with a 95% confidence interval of 1.294-9.012 (p = 0.013). Patients who continued to have positive nucleic acid tests and ongoing symptoms beyond 30 days were categorized as having a persistent infection, whereas those who achieved infection control within this timeframe were categorized as having infection recovery. Of the HM cohort, 11 did not survive beyond 30 days after diagnosis. The results from a competing risk model revealed that increased interleukin-6 levels (HR: 2.626, 95% CI: 1.361-5.075; p = 0.004) was significantly associated with persistent infection. Conversely, receiving more than two vaccine doses (HR: 0.366, 95% CI: 0.158-0.846; p = 0.019), and having high IgG levels (≥ 1000 mg/dl) (HR: 0.364, 95% CI: 0.167-0.791; p = 0.011), were associated with infection recovery. There was a notable disparity in survival rates between patients with persistent infections and infection recovery, with those in the non-persistent group demonstrating superior survival outcomes (P < 0.001).

CONCLUSIONS

In conclusion, the study determined that HM patients with COVID-19 and increased C-reactive protein levels had a higher likelihood of severe health outcomes. Persistent infection tended to be more prevalent in those with vaccine dosages (< 2 doses), lower IgG levels, and higher interleukin-6 levels.

Are any specific respiratory viruses more severe than others in recipients of allogeneic stem cell transplantation? A focus on lower respiratory tract disease

In the general population, influenza virus, respiratory syncytial virus, and SARS-CoV-2 are considered the most severe community-acquired respiratory viruses (CARVs). However, allogeneic stem cell transplant (allo-SCT) recipients may also face severe courses from other CARVs. This retrospective study compared outcomes of various CARV lower respiratory tract diseases (LRTD) in 235 adult allo-SCT recipients, excluding co-infection episodes. We included 235 adults allo-SCT recipients experiencing 353 CARV LRTD consecutive episodes (130 rhinovirus, 63 respiratory syncytial virus, 43 influenza, 43 human parainfluenza virus, 23 human metapneumovirus, 19 Omicron SARS-CoV-2, 17 common coronavirus, 10 adenovirus and 5 human bocavirus) between December 2013 and June 2023. Day 100 overall survival ranged from 78% to 90% without significant differences among CARV types. Multivariable analysis of day 100 all-cause mortality identified corticosteroid use of >1 to <30 mg/d [Hazard ratio (HR) 2.45, p = 0.02) and ≥30 mg/d (HR 2.20, p = 0.015) along with absolute lymphocyte count <0.2 × 109/L (HR 5.82, p < 0.001) and number of CARV episodes as a continuous variable per one episode increase (HR 0.48, p = 0.001) as independent risk factors for all-cause mortality. Degree of immunosuppression, rather than intrinsic CARV virulence, has the most significant impact on mortality in allo-SCT recipients with CARV-LRTD.

Omicron SARS-CoV-2 infection management and outcomes in patients with hematologic disease and recipients of cell therapy

Introduction

Scarce real-life data exists for COVID-19 management in hematologic disease (HD) patients in the Omicron era.

Purpose

To assess the current clinical management and outcome of SARS-CoV-2 infection diagnosed, identify the risk factors for severe outcomes according to the HD characteristics and cell therapy procedures in a real-world setting.

Methods

A retrospective observational registry led by the Spanish Transplant Group (GETH-TC) with 692 consecutive patients with HD from December 2021 to May 2023 was analyzed.

Results

Nearly one-third of patients (31%) remained untreated and presented low COVID-19-related mortality (0.9%). Nirmatrelvir/ritonavir was used mainly in mild COVID-19 cases in the outpatient setting (32%) with a low mortality (1%), while treatment with remdesivir was preferentially administered in moderate-to-severe SARS-CoV-2 infection cases during hospitalization (35%) with a mortality rate of 8.6%. The hospital admission rate was 23%, while 18% developed pneumonia. COVID-19-related mortality in admitted patients was 14%. Older age, autologous hematopoietic stem cell transplantation (SCT), chimeric antigen receptor T-cell therapy, corticosteroids and incomplete vaccination were factors independently associated with COVID-19 severity and significantly related with higher rates of hospital admission and pneumonia. Incomplete vaccination status, treatment with prior anti-CD20 monoclonal antibodies, and comorbid cardiomyopathy were identified as independent risk factors for COVID-19 mortality.

Conclusions

The results support that, albeit to a lower extent, COVID-19 in the Omicron era remains a significant problem in HD patients. Complete vaccination (3 doses) should be prioritized in these immunocompromised patients. The identified risk factors may help to improve COVID-19 management to decrease the rate of severe disease, ICU admissions and mortality.

A machine learning approach to identify groups of patients with hematological malignant disorders

BACKGROUND AND OBJECTIVE

Vaccination against SARS-CoV-2 in immunocompromised patients with hematologic malignancies (HM) is crucial to reduce the severity of COVID-19. Despite vaccination efforts, over a third of HM patients remain unresponsive, increasing their risk of severe breakthrough infections. This study aims to leverage machine learning's adaptability to COVID-19 dynamics, efficiently selecting patient-specific features to enhance predictions and improve healthcare strategies. Highlighting the complex COVID-hematology connection, the focus is on interpretable machine learning to provide valuable insights to clinicians and biologists.

METHODS

The study evaluated a dataset with 1166 patients with hematological diseases. The output was the achievement or non-achievement of a serological response after full COVID-19 vaccination. Various machine learning methods were applied, with the best model selected based on metrics such as the Area Under the Curve (AUC), Sensitivity, Specificity, and Matthew Correlation Coefficient (MCC). Individual SHAP values were obtained for the best model, and Principal Component Analysis (PCA) was applied to these values. The patient profiles were then analyzed within identified clusters.

RESULTS

Support vector machine (SVM) emerged as the best-performing model. PCA applied to SVM-derived SHAP values resulted in four perfectly separated clusters. These clusters are characterized by the proportion of patients that generate antibodies (PPGA). Cluster 1, with the second-highest PPGA (69.91%), included patients with aggressive diseases and factors contributing to increased immunodeficiency. Cluster 2 had the lowest PPGA (33.3%), but the small sample size limited conclusive findings. Cluster 3, representing the majority of the population, exhibited a high rate of antibody generation (84.39%) and a better prognosis compared to cluster 1. Cluster 4, with a PPGA of 66.33%, included patients with B-cell non-Hodgkin's lymphoma on corticosteroid therapy.

CONCLUSIONS

The methodology successfully identified four separate patient clusters using Machine Learning and Explainable AI (XAI). We then analyzed each cluster based on the percentage of HM patients who generated antibodies after COVID-19 vaccination. The study suggests the methodology's potential applicability to other diseases, highlighting the importance of interpretable ML in healthcare research and decision-making.

Immunogenicity and clinical effectiveness of mRNA vaccine booster against SARS-CoV-2 Omicron in patients with haematological malignancies: A national prospective cohort study

Information regarding the protective anti-SARS-CoV-2 antibody levels and the effectiveness of the mRNA vaccines against the Omicron variant in patients with haematological malignancies is limited. We prospectively followed two times BNT162b2 vaccinated oncohaematological patients (n = 1010) without prior COVID-19 for PCR-confirmed breakthrough infections during the Alpha/Delta and the Omicron phases of the pandemic. Anti-S1-IgG levels were longitudinally monitored in patients who had received the third (booster) vaccine dose. Patients with anti-S1-IgG levels <50 BAU/mL 1 month after the booster had a higher risk of Omicron infections (RR 1.91; 95% CI 1.39-2.63; p = 0.0001) and severe infections (RR 8.74; 95% CI 3.99-19.1; p < 0.0001). Conversely, the risk of severe COVID-19 was <1% with anti-S1-IgG levels >500 BAU/mL and neutralizing antibody concentrations >50 U/mL. The risks of breakthrough Omicron infections (HR 0.55; 95% CI 0.32-0.96; p = 0.034) and severe COVID-19 (HR 0.27; 95% 0.11-0.7; p = 0.0074) were lower among patients who had received the booster dose. In conclusion, low antibody levels are associated with significantly increased risk of both the breakthrough Omicron infections and severe COVID-19. The third mRNA vaccine dose improved the protection against the Omicron and reduced the risk of severe disease.

Breakthrough SARS-COV-2 infection induces broad anti-viral T cell immunity

Vaccines have curtailed the devastation wrought by COVID-19. Nevertheless, emerging variants result in a high incidence of breakthrough infections. Here we assess the impact of vaccination and breakthrough infection on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) T cell immunity. We demonstrate that COVID-19 vaccination induces robust spike-specific T cell responses that, within the CD4+ compartment, display comparable IFN-γ responses to SARS-CoV-2 infection without vaccination. Vaccine-induced CD8+ IFN-γ responses however, were significantly greater than those primed by SARS-CoV-2 infection alone. This increased responsiveness is associated with induction of novel HLA-restricted CD8+ T cell epitopes not primed by infection alone (without vaccination). Despite these augmented responses, breakthrough infection still induced de novo T cell responses against additional SARS-CoV-2 CD8+ epitopes that display HLA-associated immunodominance hierarchies consistent with those in unvaccinated COVID-19 convalescent individuals. This study demonstrates the unique modulation of anti-viral T cell responses against multiple viral antigens following consecutive yet distinct priming events in COVID-19 vaccination and breakthrough infection.

Remdesivir or Nirmatrelvir/Ritonavir Therapy for Omicron SARS-CoV-2 Infection in Hematological Patients and Cell Therapy Recipients

BACKGROUND

Scarce data exist that analyze the outcomes of hematological patients with SARS-CoV-2 infection during the Omicron variant period who received treatment with remdesivir or nirmatrelvir/ritonavir.

METHODS

This study aims to address this issue by using a retrospective observational registry, created by the Spanish Hematopoietic Stem Cell Transplantation and Cell Therapy Group, spanning from 27 December 2021 to 30 April 2023.

RESULTS

This study included 466 patients, 243 (52%) who were treated with remdesivir and 223 (48%) with nirmatrelvir/ritonavir. Nirmatrelvir/ritonavir was primarily used for mild cases, resulting in a lower COVID-19-related mortality rate (1.3%), while remdesivir was preferred for moderate to severe cases (40%), exhibiting a higher mortality rate (9%). A multivariate analysis in the remdesivir cohort showed that male gender (odds ratio (OR) 0.35, p = 0.042) correlated with a lower mortality risk, while corticosteroid use (OR 9.4, p < 0.001) and co-infection (OR 2.8, p = 0.047) were linked to a higher mortality risk. Prolonged virus shedding was common, with 52% of patients shedding the virus for more than 25 days. In patients treated with remdesivir, factors associated with prolonged shedding included B-cell malignancy as well as underlying disease, severe disease, a later onset of and shorter duration of remdesivir treatment and a higher baseline viral load. Nirmatrelvir/ritonavir demonstrated a comparable safety profile to remdesivir, despite a higher risk of drug interactions.

CONCLUSIONS

Nirmatrelvir/ritonavir proved to be a safe and effective option for treating mild cases in the outpatient setting, while remdesivir was preferred for severe cases, where corticosteroids and co-infection significantly predicted worse outcomes. Despite antiviral therapy, prolonged shedding remains a matter of concern.

Use of remdesivir for COVID-19 in patients with hematologic cancer

PURPOSES

Patients with hematologic malignancies (HM) are among the individuals with highest risk of COVID-19 complications. We report the impact of remdesivir in patients with hematologic malignancies (HM) during Omicron in Mexico City.

METHODS

All patients with HM and COVID-19 during December 2021-March 2022 were included. Socio-demographic and clinical data were collected. The primary outcome was COVID-19 progression. Variables associated with progression were analyzed.

RESULTS

115 patients were included. Median age was 50 years (IQR 35-63); 36% (N = 41) had at least one comorbidity. Fifty-two percent had non-Hodgkin lymphoma. Fifty patients (44%) had at least two doses of SARS-CoV-2 vaccine. COVID-19 was classified as mild (52.6%), moderate (9.7%), and severe/critical (28%). Twenty-eight patients (24%) received remdesivir. Nine patients received remdesivir at the ambulatory clinic (33%), the rest during hospital admission. Overall, 22(19%) patients progressed to severe/critical COVID-19; nine died due to COVID-19(8%). Hospital admission for non-COVID-19 causes was associated with higher odds of progression. Remdesivir did not reduce the risk of progression in hospitalized patients; none of the patients who received remdesivir in the ambulatory clinic progressed to severe COVID-19 or died.

CONCLUSIONS

Patients with HM and COVID-19 continue to present with high risk of complications. More prospective studies are needed to define the impact of antivirals in this high-risk group, including the best duration of treatment. Also, better vaccine coverage and access to treatment are mandatory.

Catch-up antibody responses and hybrid immunity in mRNA vaccinated patients at risk of severe COVID-19

BACKGROUND

The immunogenicity of repeated vaccination and hybrid immunity in vulnerable patients remains unclear.

METHODS

We studied the impact of iterative Covid-19 mRNA vaccination and hybrid immunity on antibody levels in immunosuppressed subjects. Patients with liver cirrhosis (n = 38), survivors of allogeneic haematopoietic stem cell transplantation (allo-HSCT) (n = 36) and patients with autoimmune liver disease (n = 14) along with healthy controls (n = 20) were monitored for SARS-CoV-2-S1 IgG after their 1st-3rd vaccine doses, 31 of whom became infected with the Omicron variant after the 2nd dose. Ten uninfected allo-HSCT recipients received an additional 4th vaccine dose.

RESULTS

Unexpectedly, immunosuppressed patients achieved antibody levels in parity with controls after the 3rd vaccine dose. In all study cohorts, hybrid immunity (effect of vaccination and natural infection) resulted in approximately 10-fold higher antibody levels than vaccine-induced immunity alone.

CONCLUSIONS

Three doses of the Covid-19 mRNA vaccine entailed high antibody concentrations even in immunocompromised individuals, and hybrid-immunity resulted further augmented levels than vaccination alone. Clinical trial registration: EudraCT 2021-000349-42.

Comparative effectiveness of mRNA-1273 and BNT162b2 COVID-19 vaccines in immunocompromised individuals: a systematic review and meta-analysis using the GRADE framework

Introduction

Despite representing only 3% of the US population, immunocompromised (IC) individuals account for nearly half of the COVID-19 breakthrough hospitalizations. IC individuals generate a lower immune response after vaccination in general, and the US CDC recommended a third dose of either mRNA-1273 or BNT162b2 COVID-19 vaccines as part of their primary series. Influenza vaccine trials have shown that increasing dosage could improve effectiveness in IC populations. The objective of this systematic literature review and pairwise meta-analysis was to evaluate the clinical effectiveness of mRNA-1273 (50 or 100 mcg/dose) vs BNT162b2 (30 mcg/dose) in IC populations using the GRADE framework.

Methods

The systematic literature search was conducted in the World Health Organization COVID-19 Research Database. Studies were included in the pairwise meta-analysis if they reported comparisons of mRNA-1273 and BNT162b2 in IC individuals ≥18 years of age; outcomes of interest were symptomatic, laboratory-confirmed SARS-CoV-2 infection, SARS-CoV-2 infection, severe SARS-CoV-2 infection, hospitalization due to COVID-19, and mortality due to COVID-19. Risk ratios (RR) were pooled across studies using random-effects meta-analysis models. Outcomes were also analyzed in subgroups of patients with cancer, autoimmune disease, and solid organ transplant. Risk of bias was assessed using the Newcastle-Ottawa Scale for observational studies. Evidence was evaluated using the GRADE framework.

Results

Overall, 17 studies were included in the pairwise meta-analysis. Compared with BNT162b2, mRNA-1273 was associated with significantly reduced risk of SARS-CoV-2 infection (RR, 0.85 [95% CI, 0.75-0.97]; P=0.0151; I2 = 67.7%), severe SARS-CoV-2 infection (RR, 0.85 [95% CI, 0.77-0.93]; P=0.0009; I2 = 0%), COVID-19-associated hospitalization (RR, 0.88 [95% CI, 0.79-0.97]; P<0.0001; I2 = 0%), and COVID-19-associated mortality (RR, 0.63 [95% CI, 0.44-0.90]; P=0.0119; I2 = 0%) in IC populations. Results were consistent across subgroups. Because of sample size limitations, relative effectiveness of COVID-19 mRNA vaccines in IC populations cannot be studied in randomized trials. Based on nonrandomized studies, evidence certainty among comparisons was type 3 (low) and 4 (very low), reflecting potential biases in observational studies.

Conclusion

This GRADE meta-analysis based on a large number of consistent observational studies showed that the mRNA-1273 COVID-19 vaccine is associated with improved clinical effectiveness in IC populations compared with BNT162b2.

mRNA-1273 SARS-CoV-2 vaccine in recently transplanted allogeneic hematopoietic cell transplant recipients: Dynamics of cellular and humoral immune responses and booster effect

Allogeneic hematopoietic stem cell transplant (HCT) recipients are at high risk of severe COVID-19 despite vaccination. Little is known about cellular response to SARS-CoV-2 vaccine in this population, especially in recently transplanted patients (RTP). In this single-center study we examined cellular and humoral response to the mRNA-1273 (Spikevax®) vaccine in recently transplanted patients (RTP, n = 49), and compared them to long-term transplanted patients (LTTP, n = 19) and healthy controls (n = 20) at three different timepoints: one and three months after the second dose (T1 and T2, respectively, 28 days apart), and one month after the third dose (T3). Controls did not receive a third dose. RTPs showed lower IgG anti-S1 titers than healthy controls at both T1 (mean 0.50 vs 0.94 arbitrary units -AU-, p < 0.0001) and T2 (0.37 vs 0.79 AU, p < 0.0001). They also presented lower titers than LTTPs at T1 (0.50 vs 0.66, p = 0.01), but no differences at T2 (0.37 vs 0.40 AU, p = 0.55). The rate of positive T-cell responses was lower in RTPs than in controls at both T1 and T2 (61.2 % vs 95 %, p = 0.007; 59.2 % vs 100 %, p = 0.001, respectively), but without statistically significant differences between transplanted groups. At T3 no differences were seen between RTPs and LTTPs as well, neither in IgG antibodies (p = 0.82) nor in cellular responses (p = 0.15), although a third dose increased the rate of positive cellular and humoral responses in approximately 50 % of recently transplanted patients. However, active immunosuppressive treatment severely diminished their chances to produce an adequate response.

Multidisciplinary recommendations for the management of CAR-T recipients in the post-COVID-19 pandemic era

The outbreak of coronavirus disease 2019 (COVID-19) posed an unprecedented challenge on public health systems. Despite the measures put in place to contain it, COVID-19 is likely to continue experiencing sporadic outbreaks for some time, and individuals will remain susceptible to recurrent infections. Chimeric antigen receptor (CAR)-T recipients are characterized by durable B-cell aplasia, hypogammaglobulinemia and loss of T-cell diversity, which lead to an increased proportion of severe/critical cases and a high mortality rate after COVID-19 infection. Thus, treatment decisions have become much more complex and require greater caution when considering CAR T-cell immunotherapy. Hence, we reviewed the current understanding of COVID-19 and reported clinical experience in the management of COVID-19 and CAR-T therapy. After a panel discussion, we proposed a rational procedure pertaining to CAR-T recipients with the aim of maximizing the benefit of CAR-T therapy in the post COVID-19 pandemic era.

SARS-CoV-2 spike-protein targeted serology test results and their association with subsequent COVID-19-related outcomes

Importance

In the absence of evidence of clinical utility, the United States' Centers for Disease Control and Prevention does not currently recommend the assessment of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) spike-protein antibody levels. Clinicians and their patients, especially immunocompromised patients, may benefit from an adjunctive objective clinical laboratory measure of risk, using SARS-CoV-2 serology.

Objective

The aim of this study is to estimate the association between SARS-CoV-2 spike-protein targeted antibody levels and clinically relevant outcomes overall and among clinically relevant subgroups, such as vaccine and immunocompetency statuses.

Design

A retrospective cohort study was conducted using laboratory-based data containing SARS-CoV-2 antibody testing results, as well as medical and pharmacy claim data. SARS-CoV-2 testing was performed by two large United States-based reference clinical laboratories, Labcorp® and Quest Diagnostics, and was linked to medical insurance claims, including vaccination receipt, through the HealthVerity Marketplace. Follow-up for outcomes began after each eligible individual's first SARS-CoV-2 semiquantitative spike-protein targeted antibody test, from 16 November 2020 to 30 December 2021.

Exposures

Exposure is defined as having SARS-CoV-2 spike-protein targeted antibody testing.

Main outcomes and measures

Study outcomes were SARS-CoV-2 infection and a serious composite outcome (hospitalization with an associated SARS-CoV-2 infection or all-cause death). Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). Propensity score matching was used for confounding covariate control.

Results

In total, 143,091 (73.2%) and 52,355 (26.8%) eligible individuals had detectable and non-detectable levels of SARS-CoV-2 spike-protein targeted antibodies, respectively. In the overall population, having detectable vs. non-detectable antibodies was associated with an estimated 44% relative reduction in SARS-CoV-2 subsequent infection risk (HR, 0.56; 95% CI 0.53-0.59) and an 80% relative reduction in the risk of serious composite outcomes (HR 0.20; 95% CI 0.15-0.26). Relative risk reductions were observed across subgroups, including among immunocompromised persons.

Conclusion and relevance

Individuals with detectable SARS-CoV-2 spike-protein targeted antibody levels had fewer associated subsequent SARS-CoV-2 infections and serious adverse clinical outcomes. Policymakers and clinicians may find SARS-CoV-2 spike-protein targeted serology testing to be a useful adjunct in counseling patients with non-detectable antibody levels about adverse risks and reinforcing appropriate actions to mitigate such risks.

Vaccination prevents severe COVID-19 outcome in patients with neutralizing type 1 interferon autoantibodies

A hallmark of patients with autoimmune polyendocrine syndrome type 1 (APS-1) is serological neutralizing autoantibodies against type 1 interferons (IFN-I). The presence of these antibodies has been associated with severe course of COVID-19. The aims of this study were to investigate SARS-CoV-2 vaccine tolerability and immune responses in a large cohort of patients with APS-1 (N = 33) and how these vaccinated patients coped with subsequent infections. We report that adult patients with APS-1 were able to mount adequate SARS-CoV-2 spike-specific antibody responses after vaccination and observed no signs of decreased tolerability. Compared with age- and gender-matched healthy controls, patients with APS-1 had considerably lower peak antibody responses resembling elderly persons, but antibody decline was more rapid in the elderly. We demonstrate that vaccination protected patients with APS-1 from severe illness when infected with SARS-CoV-2 virus, overriding the systemic danger of IFN-I autoantibodies observed in previous studies.

SARS-CoV-2-reactive antibody waning, booster effect and breakthrough SARS-CoV-2 infection in hematopoietic stem cell transplant and cell therapy recipients at one year after vaccination

The kinetics of SARS-CoV-2 reactive IgG antibodies after full vaccination and booster in allogeneic and autologous stem cell transplantation (allo-HSCT, ASCT) and chimeric antigen receptor T-cell therapy (CAR-T) are of utmost importance for estimating risk of infection. A prospective multicenter registry-based cohort study, conducted from December 2020 to July 2022 was used to analyze antibody waning over time, booster effect and the relationship of antibody response and breakthrough infection in 572 recipients (429 allo-HSCT, 121 ASCT and 22 CAR-T cell therapy). A significant decline in antibody titers was observed at 3 and 6 months after full vaccination in recipients without pre-vaccine SARS-CoV-2 infection, whereas recipients infected prior to vaccination showed higher and stable antibody titers over time. In poor responders, a booster dose was able to increase antibody titers in 83% of allo-HSCT and 58% of ASCT recipients but not in CART-T cell recipients [0%] (p < 0.01). One-year cumulative incidence of breakthrough infection was 15%, similar among cell therapy procedures. Immunosuppressive drugs at the time of vaccination [hazard ratio (HR) 1.81, p = 0.0028] and reduced intensity conditioning (HR 0.49, p = 0.011) were identified as the only conditions associated with different risk of breakthrough infection in allo-HSCT recipients. Antibody titers were associated with breakthrough infection and disease severity. No death was observed among the 72 breakthrough infections. Antibody level decay after the first two vaccine doses was common except in recipients with pre-vaccination SARS-CoV-2 infection. Poorly responding allo-HSCT recipients showed a response advantage with the booster as compared to ASCT and, especially, the null response found in CAR-T cell recipients. Antibody titers were positively correlated with the risk of breakthrough SARS-CoV-2 infection which was mainly driven by the immunosuppression status.

Assessing Vulnerability to COVID-19 in High-Risk Populations: The Role of SARS-CoV-2 Spike-Targeted Serology

Individuals at increased risk for severe coronavirus disease-2019 (COVID-19) outcomes, due to compromised immunity or other risk factors, would benefit from objective measures of vulnerability to infection based on vaccination or prior infection. The authors reviewed published data to identify a specific role and interpretation of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) spike-targeted serology testing. Specific recommendations are provided for an evidence-based and clinically-useful interpretation of SARS-CoV-2 spike-targeted serology to identify vulnerability to infection and potential subsequent adverse outcomes. Decreased vaccine effectiveness among immunocompromised individuals is linked to correspondingly high rates of breakthrough infections. Negative results on SARS-CoV-2 antibody tests are associated with increased risk for subsequent infection. "Low-positive" results on semiquantitative SARS-CoV-2 spike-targeted antibody tests may help identify persons at increased risk as well. Standardized SARS-CoV-2 spike-targeted antibody tests may provide objective information on the risk of SARS-CoV-2 infection and associated adverse outcomes. This holds especially for high-risk populations that demonstrate a relatively high rate of seronegativity. The widespread availability of such tests presents an opportunity to refine risk assessment for individuals with suboptimal SARS-CoV-2 antibody levels and to promote effective interventions. Interim federal guidance would support physicians and patients while additional investigations are pursued.

One-year breakthrough SARS-CoV-2 infection and correlates of protection in fully vaccinated hematological patients

The long-term clinical efficacy of SARS-CoV-2 vaccines according to antibody response in immunosuppressed patients such as hematological patients has been little explored. A prospective multicenter registry-based cohort study conducted from December 2020 to July 2022 by the Spanish Transplant and Cell Therapy group, was used to analyze the relationship of antibody response over time after full vaccination (at 3-6 weeks, 3, 6 and 12 months) (2 doses) and of booster doses with breakthrough SARS-CoV-2 infection in 1551 patients with hematological disorders. At a median follow-up of 388 days after complete immunization, 266 out of 1551 (17%) developed breakthrough SARS-CoV-2 infection at median of 86 days (range 7-391) after full vaccination. The cumulative incidence was 18% [95% confidence interval (C.I.), 16-20%]. Multivariate analysis identified higher incidence in chronic lymphocytic leukemia patients (29%) and with the use of corticosteroids (24.5%), whereas female sex (15.5%) and more than 1 year after last therapy (14%) were associated with a lower incidence (p < 0.05 for all comparisons). Median antibody titers at different time points were significantly lower in breakthrough cases than in non-cases. A serological titer cut-off of 250 BAU/mL was predictive of breakthrough infection and its severity. SARS-CoV-2 infection-related mortality was encouragingly low (1.9%) in our series. Our study describes the incidence of and risk factors for COVID-19 breakthrough infections during the initial vaccination and booster doses in the 2021 to mid-2022 period. The level of antibody titers at any time after 2-dose vaccination is strongly linked with protection against both breakthrough infection and severe disease, even with the Omicron SARS-CoV-2 variant.

A performance comparison of two (electro) chemiluminescence immunoassays for detection and quantitation of serum anti-spike antibodies according to SARS-CoV-2 vaccination and infections status

The information provided by SARS-CoV-2 spike (S)-targeting immunoassays can be instrumental in clinical-decision making. We compared the performance of the Elecsys® Anti-SARS-CoV-2 S assay (Roche Diagnostics) and the LIAISON® SARS-CoV-2 TrimericS IgG assay (DiaSorin) using a total of 1176 sera from 797 individuals, of which 286 were from vaccinated-SARS-CoV-2/experienced (Vac-Ex), 581 from vaccinated/naïve (Vac-N), 147 from unvaccinated/experienced (Unvac-Ex), and 162 from unvaccinated/naïve (Unvac-N) individuals. The Roche assay returned a higher number of positive results (907 vs. 790; p = 0.45; overall sensitivity: 89.3% vs. 77.6%). The concordance between results provided by the two immunoassays was higher for sera from Vac-N (ϰ: 0.58; interquartile ranges [IQR]: 0.50-0.65) than for sera from Vac-Ex (ϰ: 0.19; IQR: -0.14 to 0.52) or Unvac-Ex (ϰ: 0.18; IQR: 0.06-0.30). Discordant results occurred more frequently among sera from Unvac-Ex (34.7%) followed by Vac-N (14.6%) and Vac-Ex (2.7%). Antibody levels quantified by both immunoassays were not significantly different when <250 (p = 0.87) or <1000 BAU/ml (p = 0.13); in contrast, for sera ≥1000 BAU/ml, the Roche assay returned significantly higher values than the DiaSorin assay (p < 0.008). Neutralizing antibody titers (NtAb) were measured in 127 sera from Vac-Ex or Vac-N using a S-pseudotyped virus neutralization assay of Wuhan-Hu-1, Omicron BA.1, and Omicron BA.2. The correlation between antibody levels and NtAb titers was higher for sera from Vac-N than those from Vac-Ex, irrespective of the (sub)variant considered. In conclusion, neither qualitative nor quantitative results returned by both immunoassays are interchangeable. The performance of both assays was found to be greatly influenced by the vaccination and SARS-CoV-2 infection status of individuals.

SARS-CoV-2 Anti-Spike IgG Antibody and ACE2 Receptor Binding Inhibition Levels among Breakthrough Stage Veteran Patients

SARS-CoV-2 mRNA vaccines have been critical to curbing pandemic COVID-19; however, a major shortcoming has been the inability to assess levels of protection after vaccination. This study assessed serologic status of breakthrough infections in vaccinated patients at a Veterans Administration medical center from June through December 2021 during a SARS-CoV-2 delta variant wave. Breakthrough occurred mostly beyond 150 days after two-dose vaccination with a mean of 239 days. Anti-SARS-CoV-2 spike (S) IgG levels were low at 0 to 2 days postsymptoms but increased in subjects presenting thereafter. Population measurements of anti-S IgG and angiotensin converting enzyme-2 receptor (ACE2-R) binding inhibition among uninfected, vaccinated patients suggested immune decay occurred after 150 days with 62% having anti-S IgG levels at or below 1,000 AU comparable with breakthrough patients at 0 to 2 days postsymptom onset. In contrast, vaccination after resolved infection conferred robust enduring anti-S IgG levels (5,000 to >50,000 AU) with >90% ACE2-R binding inhibition. However, monoclonal antibody (MAb)-treated patients did not benefit from their prior infection suggesting impaired establishment of B cell memory. Analysis of boosted patients confirmed the benefit of a third vaccine dose with most having anti-S IgG levels above 5,000 AU with >90% ACE2-R binding inhibition, but a subset had levels <5,000 AU. Anti-S IgG levels >5,000 AU were associated with >90% ACE2-R binding inhibition and no documented breakthrough infections, whereas levels falling below 5,000 AU and approaching 1,000 AU were associated with breakthrough infections. Thus, quantitative antibody measurements may provide a means to guide vaccination intervals for the individual. IMPORTANCE Currently, clinicians have no guidance for the serologic assessment of SARS-Cov-2 postvaccination status regarding protection and risk of infection. Vaccination and boosters are administered blindly without evaluation of need or outcome at the individual level. The recent development of automated quantitative assays for anti-SARS-CoV-2 spike protein IgG antibodies permits accurate measurement of humoral immunity in standardized units. Clinical studies, such as reported here, will help establish protective antibody levels allowing identification and targeted management of poor vaccine responders and vaccinated subjects undergoing immune decay.

Antibody binding and neutralization of live SARS-CoV-2 variants including BA.4/5 following booster vaccination of patients with B-cell malignancies

Non-Hodgkin lymphoma and chronic lymphocytic leukemia (NHL/CLL) patients elicit inadequate antibody responses after initial SARS-CoV-2 vaccination and remain at high risk of severe COVID-19 disease. We investigated IgG, IgA, and IgM responses after booster vaccination against recent SARS-CoV-2 variants including Omicron BA.5 in 67 patients. Patients had lower fold increase and total anti-spike binding titers after booster than healthy individuals. Antibody responses negatively correlated with recent anti-CD20 therapy and low B cell numbers. Antibodies generated after booster demonstrated similar binding properties against SARS-CoV-2 variants compared to those generated by healthy controls with lower binding against Omicron variants. Importantly, 43% of patients showed anti-Omicron BA.1 neutralizing antibodies after booster and all these patients also had anti-Omicron BA.5 neutralizing antibodies. NHL/CLL patients demonstrated inferior antibody responses after booster vaccination, particularly against Omicron variants. Prioritization of prophylactic and treatment agents and vaccination of patients and close contacts with updated vaccine formulations are essential.

COVID-19 vaccine breakthrough infection among fully vaccinated healthcare workers in Duhok governorate, Iraqi Kurdistan: A retrospective cohort study

The aims of this study were: to determine the incidence of Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) infection among vaccinated healthcare workers (HCWs), assess risk factors associated with the vaccine breakthrough (BT), and compare the effectiveness of vaccine manufacturers against SARS-CoV-2 variant of concern among HCWs in Duhok governorate. It is a multicenter retrospective cohort study, which enrolled 944 HCWs through March 2022. COVID-19 vaccinated HCWs aging 18 and above were included. A random sampling process was performed by asking the participants to fill out a standardized questionnaire by means of interviews or participant-completed surveys. Fully vaccinated HCWs with positive polymerase chain reaction tests were considered to have vaccine BT infection. Two hundred and eighty-four (30.1%) out of 944 vaccinated HCWs had SARS-CoV-2 infection postvaccination, of whom 241 (84.9%) were fully vaccinated, concluding that the incidence of BT infection is 25.5%. There were 422 (44.7%) males and 522 (55.3%) females. Most vaccine BT infections had developed in SARS-CoV-2 Omicron variant (53.5%). The majority of BT infections were mild to moderate (95.5%). Occupation, namely dentist was a significant risk factor, with a p value of 0.001. HCWs with a history of SARS-CoV-2 infection prevaccination were more prone to a vaccine BT infection (p value =0.002). Pfizer vaccine manufacturers revealed the highest effectiveness against BT infection (p value =0.0001). Paramedics showed a significant association with the disease severity (p value =0.02). The three available vaccine manufacturers in the Duhok governorate are effective against COVID-19 BT infections. Dentists and paramedics were significantly associated with poor COVID-19 outcomes.

SARS-CoV-2 primary and breakthrough infections in patients with cancer: Implications for patient care

Initial reports of SARS-CoV-2 caused COVID-19 suggested that patients with malignant diseases were at increased risk for infection and its severe consequences. In order to provide early United States population-based assessments of SARS-CoV-2 primary infections in unvaccinated patients with hematologic malignancies or cancer, and SARS-CoV-2 breakthrough infections in vaccinated patients with hematologic malignancies or cancer, we conducted retrospective studies using two, unique nationwide electronic health records (EHR) databases. Using these massive databases to provide highly statistically significant data, our studies demonstrated that, compared to patients without malignancies, risk for COVID-19 was increased in patients with all cancers and with all hematologic malignancies. Risks varied with specific types of malignancy. Patients with hematologic malignancies or cancer were at greatest risk for COVID-19 during the first year after diagnosis. Risk for infection was increased for patients 65 years and older, compared to younger patients and among Black patients compared to white patients. When patients with hematologic malignancies or cancer were vaccinated against SARS-CoV-2, their risk for breakthrough infections was decreased relative to primary infections but remained elevated relative to vaccinated patients without malignancies. Compared to vaccinated patients without malignancies, vaccinated patients with hematologic malignancy or cancer showed increased risk for infection at earlier post vaccination time points. As with primary infections, risk for breakthrough infections was greatest in patients during their first year of hematologic malignancy or cancer. There were no signs of racial disparities among vaccinated patients with hematologic malignancies or cancer. These results provide the population basis to understand the significance of subsequent immunologic studies showing relative defective and delayed immunoresponsiveness to SARS-CoV-2 vaccines among patients with hematologic malignancies and cancers. These studies further provide the basis for recommendations regarding COVID-19 vaccination, vigilance and maintaining mitigation strategies in patients with hematologic malignancies and cancers.

Applicability of probabilistic graphical models for early detection of SARS-CoV-2 reactive antibodies after SARS-CoV-2 vaccination in hematological patients

Prior studies of antibody response after full SARS-CoV-2 vaccination in hematological patients have confirmed lower antibody levels compared to the general population. Serological response in hematological patients varies widely according to the disease type and its status, and the treatment given and its timing with respect to vaccination. Through probabilistic machine learning graphical models, we estimated the conditional probabilities of having detectable anti-SARS-CoV-2 antibodies at 3-6 weeks after SARS-CoV-2 vaccination in a large cohort of patients with several hematological diseases (n= 1166). Most patients received mRNA-based vaccines (97%), mainly Moderna® mRNA-1273 (74%) followed by Pfizer-BioNTech® BNT162b2 (23%). The overall antibody detection rate at 3 to 6 weeks after full vaccination for the entire cohort was 79%. Variables such as type of disease, timing of anti-CD20 monoclonal antibody therapy, age, corticosteroids therapy, vaccine type, disease status, or prior infection with SARS-CoV-2 are among the most relevant conditions influencing SARS-CoV-2-IgG-reactive antibody detection. A lower probability of having detectable antibodies was observed in patients with B-cell non-Hodgkin's lymphoma treated with anti-CD20 monoclonal antibodies within 6 months before vaccination (29.32%), whereas the highest probability was observed in younger patients with chronic myeloproliferative neoplasms (99.53%). The Moderna® mRNA-1273 compound provided higher probabilities of antibody detection in all scenarios. This study depicts conditional probabilities of having detectable antibodies in the whole cohort and in specific scenarios such as B cell NHL, CLL, MM, and cMPN that may impact humoral responses. These results could be useful to focus on additional preventive and/or monitoring interventions in these highly immunosuppressed hematological patients.