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

The immunologic outcomes and adverse events of COVID-19 vaccine booster dose in immunosuppressed people: A systematic review

Introduction

This study examines the efficacy and safety of three COVID-19 booster vaccines including mRNA-based vaccines (BNT162b2 (BioNTech/Pfizer) and/or mRNA-1273 (Moderna)), Non-Replicating Viral-Vector vaccines (ChAdOx1 nCoV-19 vaccine (AstraZeneca) and/or Ad26. COV2.S (Johnson & Johnson)), and Protein Subunit vaccine (SpikoGen) in immunosuppressed patients.

Methods

Relevant articles were systematically searched using medical subject heading (MeSH) and keywords "COVID-19" and "booster dose" or "booster vaccine" or ''fourth dose" in the online databases of PubMed, Embase, Scopus, and Web of Science. To identify eligible studies, a two-phase screening process was implemented. Initially, three researchers evaluated the studies based on the relevancy of the title and abstract.

Results

A total of 58 studies met the inclusion criteria and were included in this review. The findings suggest that booster doses offer greater protection against the disease than the primary dose. The study also compared various vaccine types, revealing that viral vector and nucleic acid vaccines outperformed inactivated vaccines. Results indicated that individuals receiving booster doses experienced superior outcomes compared to those without boosters. Vaccination against COVID-19 emerged as the most effective preventive measure against infection and symptom severity. Elevated antibody levels post-booster dose vaccination in the population signaled robust immune responses, underscoring the benefits of supplementary vaccine doses.

Conclusion

This systematic review highlights preliminary evidence supporting the immunologic outcomes and safety of COVID-19 vaccine boosters in enhancing immune responses against SARS-CoV-2. However, further research is needed to determine optimal timing intervals between primary vaccination series and boosters while considering global equity issues and variant-specific considerations.

Immune dysfunction prior to and during vaccination in multiple myeloma: a case study based on COVID-19

Infection is the leading cause of death in multiple myeloma (MM). However, the cellular composition associated with immune dysfunction is not defined. We analyzed immune profiles in the peripheral blood of patients with MM (n = 28) and B-cell chronic lymphoproliferative disorders (n = 53) vs. health care practitioners (n = 96), using multidimensional and computational flow cytometry. MM patients displayed altered distribution of most cell types (41/56, 73%), particularly within the B-cell (17/17) and T-cell (20/30) compartments. Using COVID-19 as a case study, we compared the immune response to vaccination based on 64,304 data points generated from the analysis of 1099 longitudinal samples. MM patients showed limited B-cell expansion linked to lower anti-RBD and anti-S antibody titers after the first two doses and booster. The percentages of B cells and CD4+ T cells in the blood, as well as the absolute counts of B cells and dendritic cells, predicted vaccine immunogenicity at different time points. In contrast with the humoral response, the percentage and antigen-dependent differentiation of SARS-CoV-2-specific CD8+ T cells was not altered in MM patients. Taken together, this study defined the cellular composition associated with immune dysfunction in MM and provided biomarkers such as the B-cell percentage and absolute count to individualize vaccination calendars.

Burden of COVID-19 variant omicron in immunocompromised patients in Spain: systematic review

After the COVID-19 pandemic, the omicron variant of the SARS-CoV-2 virus became the dominant lineage in Spain in 2022. Although it possesses a milder pathogenicity than previous variants, it still poses a high risk of causing severe COVID-19 for immunocompromised populations. A systematic review was conducted to assess the burden of COVID-19 in Spain among immunocompromised patients during the omicron predominance (1/04/2022-1/04/2023), using PubMed, Cochrane Library, and EPICOVIDEHA between May and July 2023. The search retrieved 217 articles, of which a total of 5 were included. Upon analysis, it was observed that immunocompromised patients during the omicron lineage predominance continue to exhibit higher rates of hospitalizations, ICU admissions, and mortality compared to the general population affected by COVID-19. Although the pandemic has ended, the risk persists for immunocompromised individuals.

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.

Prognostic value of anti-SARS-CoV-2 antibodies: a systematic review

OBJECTIVES

Globally, over 772 million cases of COVID-19 have been reported. New variants of interest with corresponding spikes in case numbers continue to be identified. Vulnerable patients, including older adults or patients with severe comorbidities, continue to be at risk. A large body of evidence has been accumulated regarding anti-SARS-CoV-2-antibodies and COVID-19 but the usefulness of antibody measurements remains unclear. This systematic review aims to assess the prognostic value of anti-SARS-CoV-2-antibodies and their usefulness for guiding booster vaccinations.

METHODS

Studies in English and published between January 2020 and October 2023 were included. Studies that relied on multiparameter-models or comprised fewer than 100 participants were excluded. PubMed and via the WHO COVID-19 research database, Embase and Medline databases were searched. Study selection and quality assessment was conducted independently by two researchers.

RESULTS

After screening 1,160 studies, 33 studies comprising >30 million individuals were included. Anti-SARS-CoV-2-antibodies were strongly associated with reduced risk of SARS-CoV-2-infection and better outcomes, including mortality. Risk of infection and COVID-19 severity decreased with increasing antibody levels.

CONCLUSIONS

Anti-SARS-CoV-2-antibodies are useful for early identification of high-risk patients and timely adjustment of therapy. Protective thresholds may be applied to advise booster vaccinations but verification in separate cohorts is required.

The impact of Bruton's tyrosine kinase inhibitor treatment on COVID-19 outcomes in Chinese patients with chronic lymphocytic leukemia

Background

Impact of B-cell depletion following treatment with Bruton tyrosine kinase-inhibitors (BTKi) on the outcome of SARS-CoV-2 infection in chronic lymphocytic leukemia (CLL) patients remain controversial. We investigated the impact of BTKi on susceptibility and the severity of COVID-19 in Chinese patients with CLL during the first wave of COVID-19 (Omicron variant).

Methods

CLL patients (n=171) visiting the Institute of Hematology, Peoples' Hospital, China (November 15, 2022- January 20, 2023) were included in the study. Seventeen patients receiving BTKi and venetoclax with or without obinutuzumab were excluded. Data from 117 patients receiving treatment with BTKi were collected using a standardized questionnaire through telephone interviews. Thirty-four patients without CLL-specific treatment served as controls. The data was analysed using IBM SPSS Software version 21 and a P value of <0.05 was considered statistically significant.

Results

The median age of patients was 67 years and majority were males (n=100). Treatment with BTKi was not associated with higher incidence of COVID-19 (74% [95% Confidence Interval (CI) 60%, 92%]) versus 74% (CI 48%, 100%) without any treatment (P=0.92). Hypoxemia was reported by 45% (32%, 61%) and 16% (4%, 41%) (P=0.01). BTKi was the only independent risk factor of hypoxemia (Hazard Ratio [HR], 4.22 [1.32, 13.50]; P = 0.02). Five (5.7%) patients with COVID-19 under BTKi required ICU admission; 4 of them died. No ICU admissions/deaths were observed in the control group.

Conclusion

In Chinese patients with CLL and treated with BTKi experienced more severe lung disease and ICU admissions due to COVID-19 than patients without CLL therapy. Frequency of infections with SARS-CoV-2, however, was not different in patients with or without BTKi treatment.

Vaccination of Adults With Cancer: ASCO Guideline

PURPOSE

To guide the vaccination of adults with solid tumors or hematologic malignancies.

METHODS

A systematic literature review identified systematic reviews, randomized controlled trials (RCTs), and nonrandomized studies on the efficacy and safety of vaccines used by adults with cancer or their household contacts. This review builds on a 2013 guideline by the Infectious Disease Society of America. PubMed and the Cochrane Library were searched from January 1, 2013, to February 16, 2023. ASCO convened an Expert Panel to review the evidence and formulate recommendations.

RESULTS

A total of 102 publications were included in the systematic review: 24 systematic reviews, 14 RCTs, and 64 nonrandomized studies. The largest body of evidence addressed COVID-19 vaccines.

RECOMMENDATIONS

The goal of vaccination is to limit the severity of infection and prevent infection where feasible. Optimizing vaccination status should be considered a key element in the care of patients with cancer. This approach includes the documentation of vaccination status at the time of the first patient visit; timely provision of recommended vaccines; and appropriate revaccination after hematopoietic stem-cell transplantation, chimeric antigen receptor T-cell therapy, or B-cell-depleting therapy. Active interaction and coordination among healthcare providers, including primary care practitioners, pharmacists, and nursing team members, are needed. Vaccination of household contacts will enhance protection for patients with cancer. Some vaccination and revaccination plans for patients with cancer may be affected by the underlying immune status and the anticancer therapy received. As a result, vaccine strategies may differ from the vaccine recommendations for the general healthy adult population vaccine.Additional information is available at www.asco.org/supportive-care-guidelines.

Monitoring Humoral Response Following BNT162b2 mRNA Vaccination against SARS-CoV-2 in Hematopoietic Stem-Cell Transplantation Patients: A Single-Center Prospective Study along with a Brief Review of Current Literature

Data on antibody response (AR) after vaccination against SARS-CoV2 in hematopoietic stem-cell transplantation setting (HSCT) were initially scarce, mainly due to the exclusion of such patients from approval studies. Shortly after the worldwide application of vaccination against SARS-CoV-2 in vulnerable populations such as patients with hematologic malignancies, limited single-center trials, including HSCT patients, were published. However, there was a great heterogeneity between them regarding the type of underlying malignancy, co-current treatment, type of vaccine, method of AR measurement, and time point of AR measurement. Herein, we present the results of a prospective study on AR after vaccination for SARS-CoV-2 using the BNT162b2 vaccine in a cohort of 54 HSCT recipients-mostly autologous from a single Unit-along with a broad review of the current literature. In our cohort, the AR positivity rate at 1 month was 80.8% and remained positive in 85.7% of patients at 3 months after vaccination. There were only nine non-responders, who were more heavily pretreated and more frequently hypogammaglobulinemic compared to responders. High antibody titers (AT), [AT ≥ 1000 U/mL], were detected in 38.5% and 30.6% of the patients at m1 and m3, respectively. A significant decline in AT between m1 and m3 was demonstrated-p < 0.0001; median AT1 and AT3 were 480.5 and 293 U/mL, respectively. A novel finding of our study was the negative impact of IgA hypogammaglobulinemia on response to vaccination. Other negative significant factors were treatment with anti-CD20 antibody at vaccination and vaccination within 18 months from HSCT. Our data indicate that HSCT recipients elicit a positive response to the BNT162b2 vaccine against SARS-CoV-2 when vaccinated at 6 months post-transplant, and vaccination should be offered to this patient population even within the post-pandemic COVID-19 era.

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.

Immune and behavioral correlates of protection against symptomatic post-vaccination SARS-CoV-2 infection

Introduction

We sought to determine pre-infection correlates of protection against SARS-CoV-2 post-vaccine inzfections (PVI) acquired during the first Omicron wave in the United States.

Methods

Serum and saliva samples from 176 vaccinated adults were collected from October to December of 2021, immediately before the Omicron wave, and assessed for SARS-CoV-2 Spike-specific IgG and IgA binding antibodies (bAb). Sera were also assessed for bAb using commercial assays, and for neutralization activity against several SARS-CoV-2 variants. PVI duration and severity, as well as risk and precautionary behaviors, were assessed by questionnaires.

Results

Serum anti-Spike IgG levels assessed by research assay, neutralization titers against Omicron subvariants, and low home risk scores correlated with protection against PVIs after multivariable regression analysis. Commercial assays did not perform as well as research assay, likely due to their lower dynamic range.

Discussion

In the 32 participants that developed PVI, anti-Spike IgG bAbs correlated with lower disease severity and shorter duration of illness.

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.

Antibody responses to SARS-CoV-2 Omicron infection in patients with hematological malignancies: A multicenter, prospective cohort study

Little is known about antibody responses to natural Omicron infection and the risk factors for poor responders in patients with hematological malignancies (HM). We conducted a multicenter, prospective cohort study during the latest Omicron wave in Chongqing, China, aiming to compare the antibody responses, as assessed by IgG levels of anti-receptor binding domain of spike protein (anti-S-RBD), to Omicron infection in the HM cohort (HMC) with healthy control cohort (HCC), and solid cancer cohort (SCC). In addition, we intend to explore the risk factors for poor responders in the HMC. Among the 466 HM patients in this cohort, the seroconversion rate was 92.7%, no statistically difference compared with HCC (98.2%, p = 0.0513) or SCC (100%, p = 0.1363). The median anti-S-RBD IgG titer was 29.9 ng/mL, significantly lower than that of HCC (46.9 ng/mL, p < 0.0001) or SCC (46.2 ng/mL, p < 0.0001). Risk factors associated with nonseroconversion included no COVID-19 vaccination history (odds ratio [OR] = 4.58, 95% confidence interval [CI]: 1.75-12.00, p = 0.002), clinical course of COVID-19 ≤ 7 days (OR = 2.86, 95% CI: 1.31-6.25, p = 0.008) and severe B-cell reduction (0-10/μL) (OR = 3.22, 95% CI: 1.32-7.88, p = 0.010). Risk factors associated with low anti-S-RBD IgG titer were clinical course of COVID-19 ≤ 7 days (OR = 2.58, 95% CI: 1.59-4.18, p < 0.001) and severe B-cell reduction (0-10/μL) (OR = 2.87, 95% CI: 1.57-5.24, p < 0.001). This study reveals a poor antibody responses to Omicron (BA.5.2.48) infection in HM patients and identified risk factors for poor responders. Highlights that HM patients, especially those with these risk factors, may be susceptible to SARS-CoV-2 reinfection, and the postinfection vaccination strategies for these patients should be tailored. Clinical trial: ChiCTR2300071830.

Respiratory virus infections after allogeneic stem cell transplantation: Current understanding, knowledge gaps, and recent advances

Before the COVID-19 pandemic, common community-acquired seasonal respiratory viruses (CARVs) were a significant threat to the health and well-being of allogeneic hematopoietic cell transplant (allo-HCT) recipients, often resulting in severe illness and even death. The pandemic has further highlighted the significant risk that immunosuppressed patients, including allo-HCT recipients, face when infected with SARS-CoV-2. As preventive transmission measures are relaxed and CARVs circulate again among the community, including in allo-HSCT recipients, it is crucial to understand the current state of knowledge, gaps, and recent advances regarding CARV infection in allo-HCT recipients. Urgent research is needed to identify seasonal respiratory viruses as potential drivers for future pandemics.

COVID-19 Antibody Seroconversion in Cancer Patients: Impact of Therapy Cessation-A Single-Center Study

BACKGROUND

The effective development of COVID-19 vaccination has mitigated its harm. Using two laboratory methods, we investigated the efficacy of the BNT162b2 mRNA and BBIBP-CorV COVID-19 vaccines on seroconversion rates in cancer patients undergoing active cancer treatment.

METHODS

SARS-CoV-2 vaccines were scheduled for 134 individuals. The consenting participants submitted three venous blood samples. Three samples: T0, T1, and T2. The ABBOTT-SARS-CoV-2 IgG II Quant and Elecsys® Anti-SARS-CoV-2 assays were used to evaluate the samples and convert the antibody titers to WHO (BAU)/mL units.

RESULTS

Cancer patients exhibited a higher seroconversion rate at T2, regardless of vaccination type, and the mean antibody titers at T1 and T2 were higher than those at T0. BBIBP-CorV patients required a booster because BNT162b2 showed a higher seroconversion rate between T0 and T1. Statistics indicate that comparing Abbott and Roche quantitative antibody results without considering the sample collection time is inaccurate.

CONCLUSIONS

COVID-19 vaccines can still induce a humoral immune response in patients undergoing cancer-targeted therapy. The strength of this study is the long-term monitoring of antibody levels after vaccination in cancer patients on active therapy using two different immunoassays. Further multicenter studies with a larger number of patients are required to validate these findings.

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.

A Pictorial Essay Describing the CT Imaging Features of COVID-19 Cases throughout the Pandemic with a Special Focus on Lung Manifestations and Extrapulmonary Vascular Abdominal Complications

With the Omicron wave, SARS-CoV-2 infections improved, with less lung involvement and few cases of severe manifestations. In this pictorial review, there is a summary of the pathogenesis with particular focus on the interaction of the immune system and gut and lung axis in both pulmonary and extrapulmonary manifestations of COVID-19 and the computed tomography (CT) imaging features of COVID-19 pneumonia from the beginning of the pandemic, describing the typical features of COVID-19 pneumonia following the Delta variant and the atypical features appearing during the Omicron wave. There is also an outline of the typical features of COVID-19 pneumonia in cases of breakthrough infection, including secondary lung complications such as acute respiratory distress disease (ARDS), pneumomediastinum, pneumothorax, and lung pulmonary thromboembolism, which were more frequent during the first waves of the pandemic. Finally, there is a description of vascular extrapulmonary complications, including both ischemic and hemorrhagic abdominal complications.

Case Report: Kinetics and durability of humoral and cellular response of SARS-CoV-2 messenger RNA vaccine in a lung and kidney transplant recipient

We present a case report of a 63-year-old female health care worker who is 15 years status post double lung transplant and six years status post living related donor kidney transplant who is healthy on a chronic immunosuppression regimen including prednisone, mycophenolate, and tacrolimus who received the SARS-CoV-2 mRNA vaccine (Pfizer-BioNTech BNT162b2) primary series and had poor initial humoral response to the COVID-19 mRNA vaccine, then demonstrated a robust, sustained immune response against S1 and S2 antigens for over seven months after receiving the recommended vaccine doses, including booster dose, without developing COVID-19 or other serious adverse events. Her immune response to vaccination indicates effective formation of anti-spike T cell memory despite chronic immunosuppression. This case report provides a comprehensive characterization of her immune response to this SARS-CoV-2 vaccination series. As vaccine effectiveness data is updated, and as better understanding of immune response including hybrid immunity emerges, these findings may reassure that recipients of SOTs may be capable of durable immune responses to emerging variants of SARS-CoV-2.

Effects of Antibody Response after Booster Vaccination on SARS-CoV-2 Breakthrough Infections and Disease Outcomes in Advanced Cancer Patients: A Prospective Analysis of the Vax-on-Third Study

(1) Background: The clinical implications of COVID-19 outbreaks following SARS-CoV-2 vaccination in immunocompromised recipients are a worldwide concern. Cancer patients on active treatment remain at an increased risk of developing breakthrough infections because of waning immunity and the emergence of SARS-CoV-2 variants. There is a paucity of data on the effects of COVID-19 outbreaks on long-term survival outcomes in this population. (2) Methods: We enrolled 230 cancer patients who were on active treatment for advanced disease and had received booster dosing of an mRNA-BNT162b2 vaccine as part of the Vax-On-Third trial between September 2021 and October 2021. Four weeks after the third immunization, IgG antibodies against the spike receptor domain of SARS-CoV-2 were tested in all patients. We prospectively evaluated the incidence of breakthrough infections and disease outcomes. The coprimary endpoints were the effects of antibody titers on the development of breakthrough infections and the impact of COVID-19 outbreaks on cancer treatment failure. (3) Results: At a median follow-up of 16.3 months (95% CI 14.5-17.0), 85 (37%) patients developed SARS-CoV-2 infection. Hospitalization was required in 11 patients (12.9%) and only 2 (2.3%) deaths related to COVID-19 outbreaks were observed. Median antibody titers were significantly lower in breakthrough cases than in non-cases (291 BAU/mL (95% CI 210-505) vs. 2798 BAU/mL (95% CI 2323-3613), p < 0.001). A serological titer cut-off below 803 BAU/mL was predictive of breakthrough infection. In multivariate testing, antibody titers and cytotoxic chemotherapy were independently associated with an increased risk of outbreaks. Time-to-treatment failure after booster dosing was significantly shorter in patients who contracted SARS-CoV-2 infection (3.1 months (95% CI 2.3-3.6) vs. 16.2 months (95% CI 14.3-17.0), p < 0.001) and had an antibody level below the cut-off (3.6 months (95% CI 3.0-4.5) vs. 14.6 months (95% CI 11.9-16.3), p < 0.001). A multivariate Cox regression model confirmed that both covariates independently had a worsening effect on time-to-treatment failure. (4) Conclusions: These data support the role of vaccine boosters in preventing the incidence and severity of COVID-19 outbreaks. Enhanced humoral immunity after the third vaccination significantly correlates with protection against breakthrough infections. Strategies aimed at restraining SARS-CoV-2 transmission in advanced cancer patients undergoing active treatment should be prioritized to mitigate the impact on disease outcomes.

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.