Humoral and cellular immune responses after influenza vaccination in kidney transplant recipients

Safety and Immunogenicity of SARS-CoV-2 mRNA Vaccine Booster Doses in Kidney Transplant Recipients: Results of a 12-mo Follow-up From a Prospective Observational Study

Background

Booster doses of SARS-CoV-2 mRNA vaccines are commonly used in kidney transplant recipients (KTRs). However, there is uncertainty regarding the waning of vaccination responses and immunological safety in KTRs.

Methods

A total of 123 KTRs were included in the final analysis of this prospective observational cohort study. The aim was to evaluate the immunogenicity and immunological safety. SARS-CoV-2 antispike IgG antibodies and anti-HLA antibodies were measured at baseline and then at months 3, 6, and 12 after vaccination with the first booster dose (ie, the third vaccine dose). Antibodies against S1 and S2 subunits of SARS-CoV-2 were evaluated using an immunochemiluminescent assay (cutoff 9.5 AU/mL, sensitivity 91.2%, and specificity 90.2%). Anti-HLA antibodies were analyzed using single-antigen bead technology.

Results

Seroconversion was reached in 65% of KTRs previously nonresponding to 2-dose mRNA vaccination; the overall seroconversion rate 3 mo after the first booster dose was 83%. Vaccination induced a durable humoral response, and the antibody levels were stable during the 12-mo study follow-up. Higher age (exponentiated beta coefficient [eβ] 0.97; 95% confidence interval [CI], 0.943-0.997) and a full dose of mycophenolate (eβ 0.296; 95% CI, 0.089-0.984) were negatively associated with SARS-CoV-2 IgG antibody levels, whereas better graft function (eβ1.021; 95% CI, 1.005-1.037) was associated positively. There were no systematic signs of anti-HLA antibody development after vaccination. However, during the follow-up, there was a nonsignificant signal of an increase in anti-HLA antibodies in those who developed COVID-19.

Conclusions

Additional booster doses of SARS-CoV-2 mRNA vaccines induce durable antibody response even in a large subset of previous nonresponders and are not associated with the risk of allosensitization. Furthermore, a signal linking COVID-19 to the development of anti-HLA antibodies was observed, and this should be confirmed and further examined (NCT05483725).

Mycophenolate mofetil hampers antibody responses to a broad range of vaccinations in kidney transplant recipients: Results from a randomized controlled study

OBJECTIVES

To study the effect of mycophenolate mofetil (MMF) on various vaccination responses in kidney transplant recipients.

METHODS

In a randomized controlled trial (EudraCT nr.: 2014-001372-66), low immunologically risk kidney transplant recipients were randomized to TAC/MMF or TAC-monotherapy (TACmono), six months post-transplantation. One year after transplantation, in a pre-specified sub-study, recipients were vaccinated against pneumococcus, tetanus and influenza. Blood was sampled before and 21 days after vaccination. Adequate vaccination responses were defined by international criteria. A post-hoc analysis was conducted on SARS-CoV-2 vaccination responses within the same cohort.

RESULTS

Seventy-one recipients received pneumococcal and tetanus vaccines (TAC/MMF: n = 37, TACmono: n = 34), with 29 also vaccinated against influenza. When vaccinated, recipients were 60 (54-66) years old, with median eGFR of 54 (44-67) ml/min, tacrolimus trough levels 6.1 (5.4-7.0) ug/L in both groups and TAC/MMF daily MMF dose of 1000 (500-2000) mg. Adequate vaccination responses were: pneumococcal (TAC/MMF 43%, TACmono 74%, p = 0.016), tetanus (TAC/MMF 35%, TACmono 82%, p < 0.0001) and influenza (TAC/MMF 20%, TACmono 71%, p = 0.0092). Only 7% of TAC/MMF responded adequately to all three compared to 36% of TACmono (p = 0.080). Additionally, 40% of TAC/MMF responded inadequately to all three, whereas all TACmono patients responded adequately to at least one vaccination (p = 0.041). Lower SARS-CoV-2 vaccination antibody responses correlated with lower pneumococcal antibody vaccination responses (correlation coefficient: 0.41, p = 0.040).

CONCLUSIONS

MMF on top of tacrolimus severely hampers antibody responses to a broad range of vaccinations.

Low incidence of de novo HLA antibodies after COVID-19 vaccination: A cohort study of patients awaiting kidney transplantation

BACKGROUND

Antibodies against human leukocyte antigen (anti-HLA Abs) are associated with an increased risk of allograft loss. Herein, we report the prospective follow-up for anti-HLA Abs formation in 103 patients with end-stage kidney disease on the waiting list for transplantation who underwent COVID-19 vaccination.

PATIENTS AND METHODS

Sera were tested before and after vaccination using Luminex technology. The cohort comprised of 62 males and 41 females with a mean age of 56 ± 14 years. The patients received BNT162b2 (80.4%), mRNA-1273 (18.5%), AZD1222 (0.40%), or ChAdOx1-S (0.80%) vaccine. Patients were tested before and within 119 ± 50, 95 ± 46 and 25 ± 26 days after the first, second, and third dose of the vaccine, respectively.

RESULTS

No significant change in calculated panel reactive antibody (cPRA) after vaccination was seen. Although 98.1% of patients had no change in anti-HLA Abs profile or cPRA after vaccination, two patients (1.9%) developed de novo anti-HLA Abs against class I or II HLA antigens. In those two patients, the cPRA changed from 0% and 63% at baseline to 9% and 90% after vaccination, respectively. Both patients received the BNT162b2 mRNA-based vaccine. The earliest detected anti-HLA Abs was 18 days after the first dose.

CONCLUSION

In rare cases, new anti-HLA antibodies were observed after COVID-19 vaccination, with potential implications for transplantation. The low incidence of this phenomenon is outweighed by the clinical benefits of vaccination.

Immunization of Solid Organ Transplant Candidates and Recipients: A 2022 Update

Immunizations are a relatively safe and cost-effective intervention to prevent morbidity and mortality associated with vaccine preventable infection (VPIs). As such, immunizations are a critical part of the care of pre and posttransplant patients and should be prioritized. New tools are needed to continue to disseminate and implement the most up-to-date vaccine recommendations for the SOT population. These tools will help both primary care providers and multi-disciplinary transplant team members taking care of transplant patients to stay abreast of evidence-based best practices regarding the immunization of the SOT patient.

Immunogenicity of Inactivated SARS-CoV-2 Vaccine (BBIBP-CorV; Sinopharm) and Short-Term Clinical Outcomes in Vaccinated Solid Organ Transplant Recipients: A Prospective Cohort Study

BackgroundImmunocompromised patients have lower seroconversion rate in response to COVID-19 vaccination. The aim of this study is to evaluate the humoral immune response with short-term clinical outcomes in solid organ transplant recipients vaccinated with SARS-CoV-2 vaccine (BBIBP-CorV; Sinopharm).MethodsThis prospective cohort was conducted from March to December 2021 in Abu Ali Sina hospital, Iran. All transplant recipients, older than 18 years were recruited. The patients received two doses of Sinopharm vaccine 4 weeks apart. Immunogenicity was evaluated through assessment of antibodies against the receptor-binding domain (RBD) of SARS-CoV-2 after the first and second dose of vaccine. The patients were followed up for 6 months after vaccination.ResultsOut of 921 transplant patients, 115 (12.5%) and 239 (26%) had acceptable anti S-RBD immunoglobulin G (IgG) levels after the first and second dose, respectively. Eighty patients (8.68%) got infected with COVID-19 which led to 45 (4.9%) of patients being hospitalized. None of the patients died during follow-up period. Twenty-four (10.9%) liver transplant recipients developed liver enzyme elevation, and increased serum creatinine was observed in 86 (13.5%) kidney transplant patients. Two patients experienced biopsy-proven rejection without any graft loss.ConclusionOur study revealed that humoral response rate of solid organ transplant recipients to Sinopharm vaccine was low.

HLA Sensitization in the Era of COVID-19: Single-Center Experience

It is well known that several viral infections are capable of triggering the formation of HLA antibodies; however, an association between SARS-CoV-2 and the development of anti-HLA antibodies is not yet confirmed. In this study, we compared the prevalence of HLA antibody before and after COVID-19 infection in a cohort of 3 groups included 58 healthy nonsensitized employees (HNEs), 130 kidney transplant recipients (KTRs), and 62 kidney transplant candidates. There were no significant changes observed in HLA class I antibodies in any of the groups, but evaluation of antibodies to HLA class II revealed a significant change in the KTR group (P = .0184) after acquiring COVID-19 infection and in the HNE group (P = .0043) when compared to the reported prevalence in a similar population. Although we observed the emergence of convalescent de novo donor-specific antibodies in 2 patients, we did not encounter any rejection episodes in the KTR group. Finally, the results of flow cytometry crossmatch in the HNE group were not consistent with the state of antibodies. In conclusion, COVID-19 infection has the potential to produce class II antibodies but with little effect on preexisting sensitization. These antibodies are likely to be transient and not necessarily causing positive crossmatch with the corresponding antigens at the proper mean fluorescent intensity and therefore should not affect access to transplantation. There is a need for further evaluation to ascertain the genuineness of these antibodies and their exact effect on transplant readiness and outcomes.

Development of donor specific antibodies after SARS-CoV-2 vaccination in kidney and heart transplant recipients

This study examined the development of new or changes in donor specific antibodies (DSA) mean-fluorescence intensity (MFI) after SARS-CoV-2 vaccination in 100 kidney and 50 heart transplant recipients. The study was performed when the Center for Disease Control and Prevention (CDC) recommended two doses of Pfizer/BioNTech [BNT162b2] and Moderna [mRNA-1273 SARS-CoV-2] vaccine or 1 dose Johnson & Johnson/Janssen [Ad26.COV2·S] vaccines for full vaccination in transplant recipients. A novel assay bead-based platform for detecting antibodies against 4 domains of the SARS-CoV-2 spike protein to determine vaccine response (SA) and one nucleocapsid protein (NC) to determine prior SARS-CoV-2 infection was utilized. These assays were performed on the multiplex, bead-based platform utilized to assay DSA levels. 61/150 patients (40.7%) had successful vaccination. 18 patients had confirmed SARS-CoV-2 infection based on positive NC assay or previous Covid-19 oropharyngeal swab. 138 patients had no DSA prior to vaccination but 3 heart recipients developed new DSA's. Among 12 patients with known DSA prior to vaccination, 4 developed new DSA's or increased MFI. All 7 patients with new or increased DSA had stable graft function without rejection and had no changes in immunosuppression. All 8 patients with stable post vaccine DSA had stable graft function and immunosuppression was not changed. The presence of DSA before vaccination was associated with subsequent development of increased MFI or new DSA's (p = 0.001). There was no association between pre-vaccine DSA and positive vaccine response (NS). There was no association with successful vaccination or prior SARS-CoV-2 infection and DSA changes (NS).

Impact of catch-up vaccinations on anti-HLA antibody response in pediatric kidney transplant candidates

BACKGROUND

Efforts have been concentrated on improving vaccination administration during the pretransplant evaluation period. However, concern for human leukocyte antigen (HLA) sensitization subsequent to vaccination exists.

METHODS

A retrospective review of pediatric kidney transplant candidates (PKTCs) ≤18 years old who had received vaccinations between February 1, 2017 and November 30, 2019 was conducted. Emergence of de novo anti-HLA antibody (HLA-Ab) 3-4 weeks postvaccinations detected by the Luminex single antigen bead assay (SAB) was evaluated. Outcomes assessed included change in the HLA-Ab mean fluorescence intensity (MFI) ≥25% from baseline, and change in preexisting HLA-Ab MFI strength, categorized as weak: 1000-2999; moderate: 3000-9999; and strong: ≥10 000.

RESULTS

Sixty vaccinations were administered to 14 patients. Forty-one potential de novo HLA-Ab were detected in five patients. After additional antibody panel testing, 5/41 potential de novo HLA-Ab were determined to be HLA specific; the remaining 36 were deemed nonspecific. The 5 de novo HLA-Ab were observed in three patients and were deemed weak antibody (Ab). Median MFI showed a significant increase for nonspecific Ab, but not de novo HLA-Ab. Median MFI values were deemed transient at 7-10 week follow-up. No HLA-donor-specific Ab developed posttransplant in the patients who developed de novo HLA-Ab.

CONCLUSION

Vaccination resulted in a transient increase in non-HLA-specific Ab. The majority of responses were non-HLA specific, hypothesized to be related to denatured antigens on single antigen beads. These data suggest limited clinical impact of vaccinations on the emergence of de novo HLA-Ab.

Correlation of Fc Receptor Polymorphisms with Pneumococcal Antibodies in Vaccinated Kidney Transplant Recipients

Several polymorphisms within Fc receptors (FCR) have been described, some of which correlate with allograft function. In the current study, we determined three Fcγ receptor and five Fcα receptor dimorphisms in 47 kidney transplant recipients who had been vaccinated against Streptococcus pneumoniae. We analyzed if FCR genotypes correlated with pneumococcal antibodies and their serotype-specific opsonophagocytic function, tested prior to and at months 1 and 12 post-vaccination. In parallel, we assessed antibodies against HLA and MICA and determined kidney function. We observed that IgG2 antibodies against pneumococci at months 1 and 12 after vaccination and IgA antibodies at month 1 differed significantly between the carriers of the three genotypes of FCGR3A rs396991 (V158F, p = 0.02; 0.04 and 0.009, respectively). Moreover, the genotype of FCGR3A correlated with serotype-specific opsonophagocytic function, reaching statistical significance (p < 0.05) at month 1 for 9/13 serotypes and at month 12 for 6/13 serotypes. Heterozygotes for FCGR3A had the lowest antibody response after pneumococcal vaccination. On the contrary, heterozygotes tended to have more antibodies against HLA class I and impaired kidney function. Taken together, our current data indicate that heterozygosity for FCGR3A may be unfavorable in kidney transplant recipients.

Insufficient response to mRNA SARS-CoV-2 vaccine and high incidence of severe COVID-19 in kidney transplant recipients during pandemic

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mRNA vaccination may fail to sufficiently protect transplant recipients against coronavirus disease 2019 (COVID-19). We retrospectively evaluated COVID-19 in kidney transplant recipients (n = 226) after BNT162b2 mRNA vaccine administration. The control group consisted of unvaccinated patients (n = 194) during the previous pandemic wave. We measured anti-spike protein immunoglobulin G (IgG) levels and cellular responses, using enzyme-linked immunosorbent spot assay, in a prospective cohort after vaccination (n = 31) and recovery from COVID-19 (n = 19). COVID-19 was diagnosed in 37 (16%) vaccinated and 43 (22%) unvaccinated patients. COVID-19 severity was similar in both groups, with patients exhibiting a comparable need for hospitalization (41% vs. 40%, p = 1.000) and mortality (14% vs. 9%, p = .726). Short posttransplant periods were associated with COVID-19 after vaccination (p < .001). Only 5 (16%) patients achieved positive SARS-CoV-2 IgG after vaccination, and 17 (89%, p < .001) recovered from COVID-19 (median IgG levels, 0.6 vs. 52.5 AU/ml, p < .001). A cellular response following vaccination was present in the majority (n = 22, 71%), with an increase in interleukin 2 secreting T cells (p < .001). Despite detectable T cell immunity after mRNA vaccination, kidney transplant recipients remained at a high risk of severe COVID-19. Humoral responses induced by vaccination were significantly lower than that after COVID-19.

SARS-CoV-2 Vaccines: Safety and Immunogenicity in Solid Organ Transplant Recipients and Strategies for Improving Vaccine Responses

Purpose of Review

While solid organ transplant (SOT) recipients are at the highest risk for severe complications and increased mortality from COVID19 disease, their vaccination against SARS-CoV-2 remains challenging due to fear of immune-mediated adverse events and suboptimal immune response. Our current review is aimed to summarize current knowledge about the safety and efficacy of SARS-CoV-2 vaccines, describe factors that are correlated with immune response, and discuss strategies to improve vaccine immunogenicity in SOT recipients.

Recent Findings

SARS-CoV-2 vaccines are safe in SOT recipients and not related to rejection or other major adverse events. The immune response to two doses of vaccine is suboptimal and correlated to age and magnitude of immunosuppression. Administration of a third vaccine dose brings to significant amplification of immune response.

Summary

This review strengthens the existing recommendation of vaccination by three doses of vaccine in all SOT recipients and completion of vaccination before transplantation if possible.

Prevention of viral infections in solid organ transplant recipients in the era of COVID-19: a narrative review

INTRODUCTION

In solid organ transplant (SOT) recipients, viral infections are associated with direct morbidity and mortality and may influence long-term allograft outcomes. Prevention of viral infections by vaccination, antiviral prophylaxis, and behavioral measures is therefore of paramount importance.

AREAS COVERED

We searched Pubmed to select publications to review current preventive strategies against the most important viral infections in SOT recipients, including SARS-CoV-2, influenza, CMV, and other herpesvirus, viral hepatitis, measles, mumps, rubella, and BK virus.

EXPERT OPINION

The clinical significance of the reduced humoral response following mRNA SARS-CoV-2 vaccines in SOT recipients still needs to be better clarified, in particular with regard to the vaccines' efficacy in preventing severe disease. Although a third dose improves immunogenicity and is already integrated into routine practice in several countries, further research is still needed to explore additional interventions. In the upcoming years, further data are expected to better delineate the role of virus-specific cell mediated immune monitoring for the prevention of CMV and potentially other viral diseases, and the role of the letermovir in the prevention of CMV in SOT recipients. Future studies including clinical endpoints will hopefully facilitate the integration of successful new influenza vaccination strategies into clinical practice.

Factors influencing the immunogenicity of influenza vaccines

Annual vaccination is the best prevention of influenza. However, the immunogenicity of influenza vaccines varies among different populations. It is important to fully identify the factors that may affect the immunogenicity of the vaccines to provide best protection for vaccine recipients. This paper reviews the factors that may influence the immunogenicity of influenza vaccines from the aspects of vaccine factors, adjuvants, individual factors, repeated vaccination, and genetic factors. The confirmed or hypothesized molecular mechanisms of these factors have also been briefly summarized.

Reduced humoral response to mRNA SARS-CoV-2 BNT162b2 vaccine in kidney transplant recipients without prior exposure to the virus

COVID-19 is associated with increased morbidity and mortality in transplant recipients. There are no efficacy data available regarding these patients with any of the available SARS-CoV-2 vaccines. We analyzed the humoral response following full vaccination with the BNT162b2 (Pfizer-BioNTech) in 136 kidney transplant recipients, and compared it to 25 controls. In order to exclude prior exposure to the virus, only participants with negative serology to SARS-CoV-2 nucleocapsid protein were included. All controls developed a positive response to spike protein, while only 51 of 136 transplant recipients (37.5%) had positive serology (p < .001). Mean IgG anti-spike level was higher in the controls (31.05 [41.8] vs. 200.5 [65.1] AU/mL, study vs. control, respectively, p < .001). Variables associated with null humoral response were older age (odds ratio 1.66 [95% confidence interval 1.17-2.69]), high-dose corticosteroids in the last 12 months (1.3 [1.09-1.86]), maintenance with triple immunosuppression (1.43 [1.06-2.15]), and regimen that includes mycophenolate (1.47 [1.26-2.27]). There was a similar rate of side effects between controls and recipients, and no correlation was found between the presence of symptoms and seroconversion. Our findings suggest that most kidney transplant recipients remain at high risk for COVID-19 despite vaccination. Further studies regarding possible measures to increase recipient's response to vaccination are required.

Influenza Virus Infection and Transplantation

Influenza infection poses significant risk for solid organ transplant recipients who often experience more severe infection with increased rates of complications, including those relating to the allograft. Although symptoms of influenza experienced by transplant recipients are similar to that of the general population, fever is not a ubiquitous symptom and lymphopenia is common. Annual inactivated influenza vaccine is recommended for all transplant recipients. Newer strategies such as using a higher dose vaccine or multiple doses in the same season appear to provide greater immunogenicity. Neuraminidase inhibitors are the mainstay of treatment and chemoprophylaxis although resistance may occur in the transplant setting. Influenza therapeutics are advancing, including the recent licensure of baloxavir; however, many remain to be evaluated in transplant recipients and are not yet in routine clinical use. Further population-based studies spanning multiple influenza seasons are needed to enhance our understanding of influenza epidemiology in solid organ transplant recipients. Specific assessment of newer influenza therapeutics in transplant recipients and refinement of prevention strategies are vital to reducing morbidity and mortality.

Epidemiology of laboratory-confirmed influenza among kidney transplant recipients compared to the general population-A nationwide cohort study

Seasonal influenza causes morbidity and mortality after organ transplantation. We quantified the detection of laboratory-confirmed influenza among kidney transplant recipients compared to the general population in a nationwide cohort. All laboratory-confirmed cases of influenza and hospitalizations due to influenza among all kidney transplant recipients in our country between 1995 and 2017 were captured with database linkage from statutory national registries. Data from the general population of Finland, population 5.5 million, were used for comparisons. Annual incidences of influenza and hospitalizations due to influenza, and standardized incidence ratios (SIR) were calculated. Altogether 3904 kidney transplant recipients with a total follow-up of 37 175 patient-years were included. Incidence of laboratory-confirmed influenza was 9.0 per 1000 patient years in 2003-2019, and 18.0 per 1000 patient years during 2015-2019. The risk of laboratory-confirmed influenza was significantly higher among kidney transplant recipients compared to the general population (SIR 5.1, 95% CI 4.5-5.7). SIR for hospitalization due to influenza was 4.4 (95% CI 3.4-4.7). Mortality of the hospitalized patients was 9%, and 5% of the patients with laboratory-confirmed influenza. Detection of laboratory-confirmed influenza is increased fivefold and risk of hospitalization due to influenza more than fourfold among kidney transplant recipients compared to the general population.

Cell-Mediated Immunogenicity of Influenza Vaccination in Patients With Cancer Receiving Immune Checkpoint Inhibitors

BACKGROUND

We assessed cell-mediated immune (CMI) responses of influenza vaccination in patients with cancer receiving immune checkpoint inhibitors (ICIs), which remain elusive.

METHODS

Vaccine-elicited CMI responses in patients receiving ICIs or cytotoxic agents were investigated by flow cytometry. Polyfunctional cells were defined as T cells that express 2 or more of interleukin 2 (IL-2), interleukin 4 (IL-4), interferon gamma (IFN-γ), and CD107a. An adequate CMI response was defined as an increase of polyfunctional T cells against both H1N1 and H3N2 strains.

RESULTS

When comparing ICI (n = 11) and cytotoxic chemotherapy (n = 29) groups, H1N1-specific IL-4 or IFN-γ-expressing CD4+ T cells, IL-2, IL-4, IFN-γ, or CD107a-expressing CD8+ T cells, H3N2-specific IFN-γ-expressing CD4+ T cells, and CD107a-expressing CD8+ T cells were more frequent in the ICI group. Fold changes in polyfunctional H3N2-specific CD4+ (median, 156.0 vs 95.7; P = .005) and CD8+ (155.0 vs 103.4; P = .044) T cells were greater in the ICI group. ICI administration was strongly associated with an adequate CMI response for both CD4+ and CD8+ T cells (P = .003).

CONCLUSIONS

CMI responses following influenza vaccination were stronger in the ICI group than in the cytotoxic chemotherapy group. Influenza vaccination should be strongly recommended in patients with cancer receiving ICIs.

Alternative strategies of posttransplant influenza vaccination in adult solid organ transplant recipients

Solid organ transplant (SOT) recipients are at increased risk of influenza disease and associated complications. The mainstay of prevention is the annual standard-dose influenza vaccine, as studies showed decreased influenza-related morbidity and mortality in vaccinated SOT recipients compared to those unvaccinated. Nonetheless, the immune response in this high-risk population is suboptimal compared to healthy individuals. Over the past two decades, several vaccination strategies have been investigated to overcome this inadequate immune response in SOT recipients. Howbeit, the best vaccination strategy and optimal timing of influenza vaccination remain unclear. This review will provide a detailed summary of studies of various influenza vaccination strategies in adult SOT recipients, discussing immunogenicity results, and addressing their limitations and knowledge gaps.

The impact of COVID-19 on kidney transplantation and the kidney transplant recipient - One year into the pandemic

The COVID‐19 pandemic has significantly changed the landscape of kidney transplantation in the United States and worldwide. In addition to adversely impacting allograft and patient survival in postkidney transplant recipients, the current pandemic has affected all aspects of transplant care, including transplant referrals and listing, organ donation rates, organ procurement and shipping, and waitlist mortality. Critical decisions were made during this period by transplant centers and individual transplant physicians taking into consideration patient safety and resource utilization. As countries have begun administering the COVID vaccines, new and important considerations pertinent to our transplant population have arisen. This comprehensive review focuses on the impact of COVID‐19 on kidney transplantation rates, mortality, policy decisions, and the clinical management of transplanted patients infected with COVID‐19.

Convalescent plasma therapy for B-cell-depleted patients with protracted COVID-19

Anti-CD20 monoclonal antibodies are widely used for the treatment of hematological malignancies or autoimmune disease but may be responsible for a secondary humoral deficiency. In the context of COVID-19 infection, this may prevent the elicitation of a specific SARS-CoV-2 antibody response. We report a series of 17 consecutive patients with profound B-cell lymphopenia and prolonged COVID-19 symptoms, negative immunoglobulin G (IgG)-IgM SARS-CoV-2 serology, and positive RNAemia measured by digital polymerase chain reaction who were treated with 4 units of COVID-19 convalescent plasma. Within 48 hours of transfusion, all but 1 patient experienced an improvement of clinical symptoms. The inflammatory syndrome abated within a week. Only 1 patient who needed mechanical ventilation for severe COVID-19 disease died of bacterial pneumonia. SARS-CoV-2 RNAemia decreased to below the sensitivity threshold in all 9 evaluated patients. In 3 patients, virus-specific T-cell responses were analyzed using T-cell enzyme-linked immunospot assay before convalescent plasma transfusion. All showed a maintained SARS-CoV-2 T-cell response and poor cross-response to other coronaviruses. No adverse event was reported. Convalescent plasma with anti–SARS-CoV-2 antibodies appears to be a very promising approach in the context of protracted COVID-19 symptoms in patients unable to mount a specific humoral response to SARS-CoV-2.

The Role of Systems Vaccinology in Understanding the Immune Defects to Vaccination in Solid Organ Transplant Recipients

Solid organ transplant recipients (SOTRs) are at increased risk for many infections, whether viral, bacterial, or fungal, due to immunosuppressive therapy to prevent organ rejection. The same immune defects that render transplanted patients susceptible to infection dampen their immune response to vaccination. Therefore, it is vital to identify immune defects to vaccination in transplant recipients and methods to obviate them. These methods can include alternative vaccine composition, dosage, adjuvants, route of administration, timing, and re-vaccination strategies. Systems biology is a relatively new field of study, which utilizes high throughput means to better understand biological systems and predict outcomes. Systems biology approaches have been used to help obtain a global picture of immune responses to infections and vaccination (i.e. systems vaccinology), but little work has been done to use systems biology to improve vaccine efficacy in immunocompromised patients, particularly SOTRs, thus far. Systems vaccinology approaches may hold key insights to vaccination in this vulnerable population.

Effect of Influenza Vaccination Inducing Antibody Mediated Rejection in Solid Organ Transplant Recipients

Introduction

Our goal was to study whether influenza vaccination induced antibody mediated rejection in a large cohort of solid organ transplant recipients (SOTR).

Methods

Serum anti-Human Leukocyte Antigen (HLA) antibodies were determined using class I and class II antibody-coated latex beads (FlowPRA^TM Screening Test) by flow cytometry. Anti-HLA antibody specificity was determined using the single-antigen bead flow cytometry (SAFC) assay and assignation of donor specific antibodies (DSA) was performed by virtual-crossmatch.

Results

We studied a cohort of 490 SOTR that received an influenza vaccination from 2009 to 2013: 110 (22.4%) received the pandemic adjuvanted vaccine, 59 (12%) within the first 6 months post-transplantation, 185 (37.7%) more than 6 months after transplantation and 136 (27.7%) received two vaccination doses. Overall, no differences of anti-HLA antibodies were found after immunization in patients that received the adjuvanted vaccine, within the first 6 months post-transplantation, or based on the type of organ transplanted. However, the second immunization dose increased the percentage of patients positive for anti-HLA class I significantly compared with patients with one dose (14.6% vs. 3.8%; P = 0.003). Patients with pre-existing antibodies before vaccination (15.7% for anti-HLA class I and 15.9% for class II) did not increase reactivity after immunization. A group of 75 (14.4%) patients developed de novo anti-HLA antibodies, however, only 5 (1.02%) of them were DSA, and none experienced allograft rejection. Only two (0.4%) patients were diagnosed with graft rejection with favorable outcomes and neither of them developed DSA.

Conclusion

Our results suggest that influenza vaccination is not associated with graft rejection in this cohort of SOTR.

Cell-Mediated Immune Responses After Influenza Vaccination of Solid Organ Transplant Recipients: Secondary Outcomes Analyses of a Randomized Controlled Trial

BACKGROUND

Despite annual immunization, solid organ transplant (SOT) patients remain at increased risk for severe influenza infection because of suboptimal vaccine immunogenicity. We aimed to compare the CD4+ and CD8+ T-cell responses of the high-dose (HD) and the standard-dose (SD) trivalent inactivated vaccine.

METHODS

We collected peripheral blood mononuclear cells pre- and postimmunization from 60 patients enrolled in a randomized trial of HD versus SD vaccine (30 HD; 30 SD) during the 2016-2017 influenza season.

RESULTS

The HD vaccine elicited significantly greater monofunctional and polyfunctional CD4+ and CD8+ T-cell responses against influenza A/H1N1, A/H3N2, and B. For example, median vaccine-elicited influenza-specific polyfunctional CD4+ T cells were higher in recipients of the HD than SD vaccine after stimulation with influenza A/H1N1 (1193 vs 0 per 106 CD4+ T cells; P = .003), A/H3N2 (1154 vs 51; P = .008), and B (1102 vs 0; P = .001). Likewise, vaccine-elicited influenza-specific polyfunctional CD8+ T cells were higher in recipients of the HD than SD vaccine after stimulation with influenza B (367 vs 0; P = .002).

CONCLUSIONS

Our study provides novel evidence that HD vaccine elicits greater cellular responses compared with the SD vaccine in SOT recipients, which provides support to preferentially consider use of HD vaccination in the SOT setting.

T-cell responses following Natural Influenza Infection or Vaccination in Solid Organ Transplant Recipients

Little is known about cell-mediated immune responses to natural influenza infection in solid organ transplant (SOT) patients. The aim of our study was to evaluate the CD4⁺ and CD8⁺ responses to influenza A and B infection in a cohort of SOT patients. We collected peripheral blood mononuclear cells at influenza diagnosis and four weeks later from 31 SOT patients during the 2017–2018 influenza season. Infection-elicited influenza-specific CD4⁺ and CD8⁺ T-cell responses were measured using flow cytometry and intracellular cytokine staining and compared to responses following influenza vaccine in SOT patients. Natural infection was associated with a significant increase in CD4⁺ T-cell responses. For example, polyfunctional cells increased from 21 to 782 and from 193 to 1436 cells per 10⁶ CD4⁺ T-cells among influenza A/H3N2 and B-infected patients (p = 0.006 and 0.004 respectively). Moreover, infection-elicited CD4⁺ responses were superior than vaccine-elicited responses for influenza A/H1N1 (931 vs 1; p = 0.026), A/H3N2 (647 vs 1; p = 0.041) and B (619 vs 1; p = 0.004). Natural influenza infection triggers a significant increase in CD4⁺ T-cell responses in SOT patients. Infection elicits significantly stronger CD4⁺ responses compared to the influenza vaccine and thereby likely elicits better protection against reinfection.

A Double-Blind, Randomized Trial of High-Dose vs Standard-Dose Influenza Vaccine in Adult Solid-Organ Transplant Recipients

Background

The annual standard-dose (SD) influenza vaccine has suboptimal immunogenicity in solid organ transplant recipients (SOTRs). Influenza vaccine that contains higher doses of antigens may lead to greater immunogenicity in this population.

Methods

We conducted a randomized, double-blind trial to compare the safety and immunogenicity of the 2016-2017 high-dose (HD; FluzoneHD, Sanofi) vs SD (Fluviral, GSK) influenza vaccine in adult SOTRs. Preimmunization and 4-week postimmunization sera underwent strain-specific hemagglutination inhibition assay.

Results

We enrolled 172 patients who received study vaccine, and 161 (84 HD; 77 SD) were eligible for analysis. Seroconversion to at least 1 of 3 vaccine antigens was present in 78.6% vs 55.8% in HD vs SD vaccine groups (P < .001), respectively. Seroconversions to A/ H1N1, A/H3N2, and B strains were 40.5% vs 20.5%, 57.1% vs 32.5%, and 58.3% vs 41.6% in HD vs SD vaccine groups (P = .006, P = .002, P = .028, respectively). Post-immunization geometric mean titers of A/H1N1, A/H3N2, and B strains were significantly higher in the HD group (P = .007, P = .002, P = .033). Independent factors associated with seroconversion to at least 1 vaccine strain were the use of HD vaccine (odds ratio [OR], 3.23; 95% confidence interval [CI], 1.56-6.67) and use of mycophenolate doses <2 g daily (OR, 2.76; 95% CI, 1.12-6.76).

Conclusions

HD vaccine demonstrated significantly better immunogenicity than SD vaccine in adult transplant recipients and may be the preferred influenza vaccine for this population.

Clinical Trials Registration

NCT03139565.

Sex-Specific Differences in HLA Antibodies after Pneumococcal Vaccination in Kidney Transplant Recipients

In transplant recipients vaccination against Streptococcus pneumoniae is recommended to reduce mortality from invasive pneumococcal disease. It is still debated if vaccination in transplant recipients triggers alloresponses. Therefore, it was our aim to define if vaccination with Prevenar 13^®, a 13-valent, conjugated pneumococcal vaccine (Pfizer, New York, NY, USA) that acts T cell dependently, induces human leukocyte antigen (HLA) antibodies in clinically stable kidney transplant recipients. Forty-seven patients were vaccinated once with Prevenar 13^® and HLA antibodies were determined prior to vaccination and at month 1 and 12 thereafter. In parallel, pneumococcal IgG antibodies were measured. Using Luminex™ Mixed Beads technology (One Lambda/Thermo Fisher, Canoga Park, CA, USA) we observed overall no change in HLA antibodies after vaccination. Pneumococcal antibodies increased significantly at month 1 (p < 0.0001) and remained elevated at month 12 (p < 0.005). A more detailed analysis of HLA antibodies showed that in 18 females HLA class I and II antibodies increased significantly at month 1 and 12 (p < 0.05); whereas in 29 males HLA class I and II antibodies tended to decrease. Using Luminex™ Single Antigen Beads assay, no de novo donor-specific HLA antibodies were detected after vaccination. In conclusion, the current data indicate that females may be more susceptible to the induction of (non-specific) HLA antibodies after vaccination.

Effects of the influenza vaccine on pediatric kidney transplant outcomes

The influenza vaccine is critical for preventing influenza-related complications in transplant patients. Previous studies demonstrated de novo donor-specific antibody formation and rejection following the influenza vaccination. This risk has not been adequately assessed in the pediatric population. We performed a single-center retrospective analysis of 187 unique pediatric kidney transplant recipients, transplanted from January 1, 2006, to December 31, 2015, assessing for an association of the influenza vaccination with various transplant outcomes. The influenza vaccine was received by 125 of 187 patients within the first year post-transplant. Using log-rank tests and Kaplan-Meier curves, vaccinated patients had a significantly lower risk of mortality (P = 0.048). There were no differences in death-censored graft survival (P = 0.253), graft survival (P = 0.098), or rejection (P = 0.195) between vaccinated and unvaccinated groups. To address the problem of multiple exposures for a yearly vaccine, Cox proportional hazards regression was utilized with post-transplant vaccination status considered as a time-dependent covariate; analyses were performed using both a 360- and 180-day vaccination period following any post-transplant influenza vaccination. In this model, being vaccinated did not result in a significant difference in mortality (HR 0.90 [0.16, 5.15], P = 0.91), death-censored graft survival (HR 0.70 [0.31, 1.58], P = 0.39), graft survival (HR 0.69 [0.32, 1.49], P = 0.34), or rejection (HR 0.67 [0.37, 1.19], P = 0.17). Eight patients developed de novo donor-specific antibodies following the first post-transplant influenza vaccination; three then developed biopsy-proven rejection. These results suggest influenza vaccination is safe in pediatric kidney transplant recipients, and larger prospective studies are required to conclusively confirm our findings.

Vaccinations in kidney transplant recipients: Clearing the muddy waters

Vaccine preventable diseases account for a significant proportion of morbidity and mortality in transplant recipients and cause adverse outcomes to the patient and allograft. Patients should be screened for vaccination history at the time of pre-transplant evaluation and vaccinated at least four weeks prior to transplantation. For non-immune patients, dead-vaccines can be administered starting at six months post-transplant. Live attenuated vaccines are contraindicated after transplant due to concern for infectious complications from the vaccine and every effort should be made to vaccinate prior to transplant. Since transplant recipients are on life-long immunosuppression, these patients may have lower rates of serological conversion, lower mean antibody titers and waning of protective immunity over shorter period as compared to general population. Recommendations regarding booster dose in kidney transplant recipients with sub-optimal serological response are lacking. Travel plans should be part of routine post-transplant assessment and pre-travel vaccines and counseling should be provided. More studies are needed on vaccination schedules, serological response, need for booster doses and safety of live attenuated vaccines in this special population.

Immunogenicity and safety of double versus standard dose of the seasonal influenza vaccine in solid-organ transplant recipients: A randomized controlled trial

BACKGROUND

The use of vaccines with higher doses of antigen is an attractive strategy to improve the immunogenicity of influenza vaccination in transplant recipients. However, the effect of vaccination with a double-dose (DD) containing 30 µg of antigen in this population remains unknown.

METHODS

We performed a randomized controlled trial to compare the immunogenicity and safety of DD (30 µg) vs. standard dose (SD, 15 µg) of a trivalent inactivated influenza vaccine in kidney and liver transplant recipients. Immunogenicity was assessed by hemagglutination-inhibition assay. Vaccine response was defined as seroconversion to at least one viral strain 2 weeks after vaccination and seroprotection as a titer ≥40.

RESULTS

Sixty-three kidney and 16 liver transplant recipients were enrolled. Forty patients received the DD and 39 the SD vaccine. Overall, 40% of patients in the DD compared to 26% in the SD group (P = 0.174) responded to vaccine. In the DD arm, more patients were seroprotected to all viral strains after vaccination (88% vs 69%, P = 0.048). Post vaccination geometric mean titers of antibodies were 131.9 vs. 89.7 (P = 0.187) for H1N1, 185.4 vs. 138.7 (P = 0.182) for H3N2, and 96.6 vs. 68.8 (P = 0.081) for influenza B with the DD vs. SD. In both groups, most of the adverse events were mild and no vaccine-related severe adverse events were observed.

CONCLUSION

Double-dose influenza vaccine is safe and may increase antibody response in transplant recipients. In this population, DD vaccination could be an alternative when high-dose vaccine is not available. NCT02746783.

Case report: A transplant candidate with unexpected serum reactivity against the 45KE eplet on HLA-B alleles

This case report describes the serum antibody specificity against the 45KE eplet which had not been yet shown to be antibody-verified. This antibody was produced by a 41-year-old European male with Berger's disease. His serum had HLA class I antibody reactivity as determined in IgG binding assays with single allele panels (OneLambda, ThermoFisher, Lot 8 and Lot 9). The HLAMatchmaker analysis revealed reproducible serum reactivity only with alleles carrying the 45KE eplet. The cause of this 45KE-specific immunization is unknown because this male patient had never been transfused nor received a previous transplant, Moreover, his mother's HLA type did not have any 45KE-carrying allele. This finding might be related to observations reported in the literature about the appearance of HLA-reactive antibodies following influenza vaccination but this possibility could not be investigated.

Vaccination practices in End Stage Renal Failure and Renal Transplantation; Review of current guidelines and recommendations

Due to the increased burden of infectious complications following solid organ transplantation, vaccination against common pathogens is a hugely important area of discussion and application in clinical practice. Reduction in infectious complications will help to reduce morbidity and mortality post-transplantation. Immunisation history is invaluable in the work-up of potential recipients. Knowledge of the available vaccines and their use in transplant recipients, donors and healthcare providers is vital in the delivery of quality care to transplant recipients. This article will serve as an aide-memoire to transplant physicians and health care professionals involved in managing transplant recipients as it provides an overview of different types of vaccines, timing of vaccination, vaccines contraindicated post solid organ transplantation and travel vaccines.

Effect of Influenza Vaccine in Patients With Kidney Transplant

BACKGROUND

Among infectious diseases, influenza is the most common cause of infection in Japan and worldwide. We aimed to evaluate the effect of influenza vaccination in kidney transplantation (KTx) recipients.

METHODS

We retrospectively evaluated the records of 98 participants who underwent KTx at our institution between March 2009 and May 2016. All patients received tacrolimus or cyclosporine, mycophenolate mofetil, and methylprednisolone for maintenance immunosuppression after KTx. In accordance with the criteria of our institution, everolimus was administered for the maintenance of immunosuppression after KTx. We compared the rate of influenza infection during the 2016-2017 season (8 months, from October 2016-May 2017) between KTx patients treated with 1 or 2 doses of influenza vaccine (treatment group, n = 71) and KTx patients who did not receive a vaccine (nontreatment group, n = 27).

RESULTS

Among patient characteristics, only the prevalence of diabetes mellitus differed significantly between the groups (treatment group: 9.9%, 7 of 71 patients; nontreatment group: 29.6%, 8 of 21 patients; P = .02). Influenza infection occurred at similar rates in the 2 groups (treatment group, 5.63% 4 of 71 patients; nontreatment group: 3.70%, 1 of 27 patients; P = .70).

CONCLUSIONS

Among KTx patients managed in our institution, treatment with 1 or 2 doses of influenza vaccine did not reduce the rate of influenza infection in the 2016-2017 season, suggesting that influenza vaccination may currently be ineffective in KTx patients.

Does vaccination in solid-organ transplant recipients result in adverse immunologic sequelae? A systematic review and meta-analysis

BACKGROUND

Clinical guidelines recommend vaccinations for solid-organ transplant recipients. However, concern exists that vaccination may stimulate adverse alloimmune responses.

METHODS

We systematically reviewed the published literature regarding this aspect of vaccine safety. Electronic databases were searched for interventional and observational studies assessing de novo donor-specific antibodies (DSA) and rejection episodes after vaccination against infectious pathogens. Graft loss was also assessed. A meta-analysis was conducted for prospective, controlled studies. PRISMA reporting guidelines were followed.

RESULTS

Ninety studies (15,645 vaccinated patients and 42,924 control patients) were included. Twelve studies included control groups. The incidence of de novo DSA (14 studies) was 23 of 1,244 patients (1.85%) at 21 to 94 days. The incidence of rejection (83 studies) was 107 episodes in 5,116 patients (2.1%) at 0.7 to 6 months. Meta-analysis of prospective controlled studies (n = 8) showed no increased rejection risk with vaccination compared with no vaccination (RR 1.12, 95% CI 0.75 to 1.70). This finding was supported by data from 3 registry analyses.

CONCLUSIONS

Although the current evidence lacks high-quality, controlled studies, the currently available data provide reassurance that clinicians should recommend appropriate vaccination for their transplant patients as the risk of de novo DSA and rejection is relatively low.

Infectious pathogens may trigger specific allo-HLA reactivity via multiple mechanisms

Transplant recipients can be sensitized against allo-HLA antigens by previous transplantation, blood transfusion, or pregnancy. While there is growing awareness that multiple components of the immune system can act as effectors of the alloresponse, the role of infectious pathogen exposure in triggering sensitization and allograft rejection has remained a matter of much debate. Here, we describe that exposure to pathogens may enhance the immune response to allogeneic HLA antigens via different pathways. The potential role of allo-HLA cross-reactivity of virus-specific memory T cells, activation of innate immunity leading to a more efficient induction of the adaptive alloimmune response by antigen-presenting cells, and bystander activation of existing memory B cell activation will be discussed in this review.

Heterologous Immune Responses to Influenza Vaccine in Kidney Transplant Recipients

Influenza vaccine is known to have suboptimal immunogenicity in transplant recipients. Despite this, influenza vaccine may have the added benefit of inducing a cross-reactive immune response to viral strains not found in the vaccine. This is termed "heterologous immunity" and has not been assessed previously in transplant patients. Pre- and postvaccination sera from kidney transplant recipients (n = 60) immunized with the 2012-2013 adjuvanted or nonadjuvanted influenza vaccine underwent testing by hemagglutination inhibition assay for strains not present in vaccine: A/New Caledonia/20/99 (H1N1), A/Texas/50/2012 (H3N2) and B/Brisbane/60/2008. The geometric mean titer of antibody to heterologous strains increased after vaccine (H1N1: 80.0 to 136.1, p < 0.001; H3N2: 23.3 to 77.3, p < 0.001; B: 13.3 to 19.5, p < 0.001). Seroconversion rates were 16.7%, 41.7%, and 13.3%, respectively. No differences in heterologous response were seen in the adjuvanted versus nonadjuvanted groups. Patients were more likely to seroconvert for a cross-reactive antigen if they seroconverted for the specific vaccine antigen. Seroconversion to heterologous A/H3N2, for example, was 84.0% for homologous H3N2 seroconverters versus 11.4% for nonseroconverters (p < 0.001). This study provides novel evidence that transplant recipients are able to mount significant cross-protective responses to influenza vaccine that may be an additional, previously unknown benefit of immunization.

Immunizations in solid organ and hematopoeitic stem cell transplant patients: A comprehensive review

The Solid Organ Transplantation (SOT) and Haematopoietic Stem Cell Transplantation (HSCT) population is continuously increasing as a result of broader indications for transplant and improved survival. Infectious diseases, including vaccine-preventable diseases, are a significant threat for this population, primarily after but also prior to transplantation. As a consequence, clinicians must ensure that patients are optimally immunized before transplantation, to provide the best protection during the early post-transplantation period, when immunosuppression is the strongest and vaccine responses are poor. After 3-6 months, inactivated vaccines immunization can be resumed. By contrast, live-attenuated vaccines are lifelong contraindicated in SOT patients, but can be considered in HSCT patients at least 2 years after transplantation, if there is no immunosuppression or graft-versus-host-disease. However, because of the advantages of live-attenuated over inactivated vaccines--and also sometimes the absence of an inactivated alternative--an increasing number of prospective studies on live vaccine immunization after transplantation are performed and give new insights about safety and immunogenicity in this population.

Randomized Controlled Trial of Adjuvanted Versus Nonadjuvanted Influenza Vaccine in Kidney Transplant Recipients

BACKGROUND

Influenza vaccine containing an oil-in-water emulsion adjuvant (MF-59) may lead to greater immunogenicity in organ transplant recipients. However, alloimmunization may be a concern with adjuvanted vaccines.

METHODS

We conducted a randomized trial comparing the safety and immunogenicity of adjuvanted versus nonadjuvanted influenza vaccine in adult kidney transplant patients. Patients were randomized 1:1 to receive 2012 to 2013 influenza vaccine with or without MF59 adjuvant. Preimmunization and postimmunization sera underwent strain-specific hemagglutination inhibition assay. HLA alloantibody was determined by Luminex single-antigen bead assay.

RESULTS

We randomized 68 patients and 60 (29 nonadjuvanted; 31 adjuvanted) had complete samples available at follow-up. Seroconversion to at least 1 of 3 influenza antigens was present in 71.0% versus 55.2% in adjuvanted versus nonadjuvanted vaccine respectively (P = 0.21). Geometric mean titers and seroprotection rates were similar between groups. Seroconversion rates were especially low in those on MMF of 2 g or greater daily (44.4% vs 71.4%; P = 0.047). In the subgroup of patients 18 to 64 years old, seroconversion was significantly greater with adjuvanted vaccine (odds ratio, 6.10; 95% confidence interval, 1.25-28.6). There were no increases in HLA alloantibodies in patients who received adjuvanted vaccine.

CONCLUSIONS

Adjuvanted vaccine was safe and had similar immunogenicity to standard vaccine in the overall transplant cohort but did show a potential immunogenicity benefit for the 18 to 64 years age group.

Humoral, T-cell and B-cell immune responses to seasonal influenza vaccine in solid organ transplant recipients receiving anti-T cell therapies

BACKGROUND

We analyzed the impact of the anti-T-cell agents basiliximab and antithymocyte globulins (ATG) on antibody and cell-mediated immune responses after influenza vaccination in solid-organ transplant recipients.

METHODS

71 kidney and heart transplant recipients (basiliximab [n=43] and ATG [n=28]) received the trivalent influenza vaccine. Antibody responses were measured at baseline and 6 weeks post-vaccination by hemagglutination inhibition assay; T-cell responses were measured by IFN-γ ELISpot assays and intracellular cytokine staining (ICS); and influenza-specific memory B-cell (MBC) responses were evaluated using ELISpot.

RESULTS

Median time of vaccination from transplantation was 29 months (IQR 8-73). Post-vaccination seroconversion rates were 26.8% for H1N1, 34.1% for H3N2 and 4.9% for influenza B in the basiliximab group and 35.7% for H1N1, 42.9% for H3N2 and 14.3% for influenza B in the ATG group (p=0.44, p=0.61, and p=0.21, respectively). The number of influenza-specific IFN-γ-producing cells increased significantly after vaccination (from 35 to 67.5 SFC/10(6) PBMC, p=0.0007), but no differences between treatment groups were observed (p=0.88). Median number of IgG-MBC did not increase after vaccination (H1N1, p=0.94; H3N2 p=0.34; B, p=0.79), irrespective of the type of anti-T-cell therapy.

CONCLUSIONS

After influenza vaccination, a significant increase in antibody and T-cell immune responses but not in MBC responses was observed in transplant recipients. Immune responses were not significantly different between groups that received basiliximab or ATG.

Effect of the adjuvanted (AS03) A/H1N1 2009 pandemic influenza vaccine on the risk of rejection in solid organ transplant recipients in England: a self-controlled case series

OBJECTIVE

To assess the risk of solid organ transplant (SOT) rejection after vaccination with the adjuvanted (AS03) A/H1N1 2009 pandemic influenza vaccine Pandemrix.

DESIGN

Self-controlled case series (SCCS) in the UK Clinical Practice Research Datalink (CPRD) and its linked component of the Hospital Episodes Statistics (HES) inpatient database. Analyses were conducted using the SCCS method for censored, perturbed or curtailed post-event exposure.

PARTICIPANTS

Of the 184 transplant recipients having experienced at least one SOT rejection (liver, kidney, lung, heart or pancreas) during the study period from 1 October 2009 to 31 October 2010, 91 participants were included in the main analysis, of which 71 had been exposed to Pandemrix.

MAIN OUTCOME MEASURES

Occurrence of SOT rejection during risk (30 and 60 days after any Pandemrix dose) and control periods. Covariates in the CPRD included time since transplantation, seasonal influenza vaccination, bacterial and viral infections, previous SOT rejections and malignancies.

RESULTS

The relative incidence (RI) of rejection of any one of the five transplanted organs, adjusted for time since transplantation, was 1.05 (95% CI 0.52 to 2.14) and 0.80 (95% CI 0.42 to 1.50) within 30 and 60 days after vaccination, respectively. Similar estimates were observed for rejection of a kidney only, the most commonly transplanted organ (RI within 30 days after vaccination: 0.85 (95% CI 0.38 to 1.90)). Across various models and sensitivity analyses, RI estimates remained stable and within a consistent range around 1.0.

CONCLUSIONS

These results suggest a reassuring safety profile for Pandemrix with regard to the risk of rejection in SOT recipients in England and contribute to inform the benefit-risk of AS03-adjuvanted pandemic influenza vaccines in transplanted patients in the event of future pandemics.

TRIAL REGISTRATION NUMBER

NCT01715792.

Comparing Humoral and Cellular Immune Response Against HBV Vaccine in Kidney Transplant Patients

Host protection upon vaccination usually results from the complex interplay of humoral and cellular components of the immune system. Exploring hepatitis B surface antigen (HBsAg)-specific T cell responses and their correlation with humoral responses under immunosuppression, we analyzed 51 renal transplant recipients, differing in HBV vaccine-specific antibody titers (non [NRs]-, low [LRs]-, and high responders [HRs]) and in 22 healthy controls (HCs) in a cross-sectional study. HBsAg-specific T cells were analyzed by flow cytometry according to expression of activation markers CD40L and/or CD69, and the cytokines IFNγ, IL-2, TNFα, and IL-17. No significant differences in responder rate and magnitude of HBsAg-specific T cell responses were found between HCs and HRs. Interestingly, HBsAg-specific Th-cells were also observed in 50% of humoral NRs. Frequencies of HBsAg-specific CD40L+ Th-cells were significantly higher in HRs compared to LRs (p = 0.009) and in LRs in comparison to NRs (p = 0.043). All but NRs showed a predominance of multi-potent HBsAg-specific TNFα+IL-2+ Th-cells. As expected, HBsAg-specific CD8(+) T cells were rarely found. In conclusion, mounting of hepatitis B vaccine-specific T cell responses is possible in kidney transplant recipients despite immunosuppression. Detection of HBV-specific Th-cells in a significant proportion of humoral NRs contributes to the current discussion on conferring immune protection by cellular memory in such patients.

Immunizations following solid-organ transplantation

PURPOSE OF REVIEW

To highlight the latest evidence for the use of key vaccines that are recommended in organ transplant candidates and recipients.

RECENT FINDINGS

Influenza vaccine is the best studied vaccine; factors affecting immunogenicity of this vaccine include time from transplant, use of mycophenolate mofetil and type of transplant. Newer formulations of influenza vaccine are available, but data for these are limited. Updated recommendations include giving conjugated pneumococcal vaccine to adult transplant candidates and recipients followed by the polysaccharide vaccine to increase serotype coverage. Human papillomavirus vaccine should also be given to transplant recipients, although the immunogenicity may be suboptimal. Quadrivalent meningococcal conjugate vaccine needs to be given in special circumstances such as to patients who are starting eculizumab therapy. Live vaccines in general are contraindicated, although increasing safety data are emerging for Varicella vaccine. Herpes Zoster vaccine may be offered prior to transplant, although the utility of this strategy regarding protection from shingles after transplant is not known. Newer vaccines such as inactivated zoster vaccine and vaccines for the prevention of cytomegalovirus are under study.

SUMMARY

Immunization for organ transplant recipients is an important part of pretransplant evaluation and the long-term care of the transplant recipient.

Serologic response after vaccination against influenza (A/H1N1)pdm09 in children with renal disease receiving oral immunosuppressive drugs

A limited number of reports are available regarding the effect of the influenza vaccine in pediatric patients receiving steroid and immunosuppressant therapy. The influenza A(H1N1)pdm09 vaccine was administered to 15 children with renal disease who were receiving steroid and immunosuppressant therapy (treatment group) and 23 children with who were not receiving these drugs (non-treatment group). Titer transition of the hemagglutination inhibition antibody was compared between the 2 groups immediately before vaccination and 4 weeks and 6 months after vaccination. Multivariate analysis showed a significant correlation between geometric mean titer, SCR, and SPR with age, while no correlation was observed between treatment with immunosuppressant therapy and efficacy. No serious adverse reactions occurred after vaccination. This strain is not present in existing influenza vaccines, and A(H1N1)pdm09HA vaccination was administered alone in 2009. The children in this study had not previously been exposed to this strain. Therefore, we evaluated the effect of the A(H1N1)pdm09HA vaccine without the effects of vaccination or past infection with A(H1N1)pdm09HA or A(H3N2) vaccination in the previous year.

Live virus vaccines in transplantation: friend or foe?

Solid organ and hematopoietic stem cell transplant recipients may be exposed to diseases which may be prevented through live attenuated virus vaccines (LAVV). Because of their immunosuppression, these diseases can lead to severe complications in transplant recipients. Despite increasing evidence regarding the safety and effectiveness of certain LAVV, these vaccines are still contraindicated for immunocompromised patients, such as transplant recipients. We review the available studies on LAVV, such as varicella zoster, measles-mumps-rubella, influenza, yellow fever, polio, and Japanese encephalitis vaccines in transplant patients. We discuss the current recommendations and the potential risks, as well as the expected benefits of LAVV immunization in this population.

HLA sensitisation: can it be prevented?

Human leukocyte antigen (HLA) sensitisation occurs after transfusion of blood products and transplantation. It can also happen spontaneously through cross-sensitisation from infection and pro-inflammatory events. Patients who are highly sensitised face longer waiting times on organ allocation programmes, more graft rejection and therefore more side effects of immunosuppression, and poorer graft outcomes. In this review, we discuss these issues, along with the limitations of modern HLA detection methods, and potential ways of decreasing HLA antibody development. We do not discuss the removal of antibodies after they have developed.

Randomized, double-blind comparison of standard-dose vs. high-dose trivalent inactivated influenza vaccine in pediatric solid organ transplant patients

Children who have undergone SOT mount a lower immune response after vaccination with TIV compared to healthy controls. HD or SD TIV in pediatric SOT was given to subjects 3-17 yr and at least six months post-transplant. Subjects were randomized 2:1 to receive either the HD (60 μg) or the SD (15 μg) TIV. Local and systemic reactions were solicited after each vaccination, and immune responses were measured before and after each vaccination. Thirty-eight subjects were enrolled. Mean age was 11.25 yr; 68% male, 45% renal, 26% heart, 21% liver, 5% lung, and 5% intestinal. Twenty-three subjects were given HD and 15 SD TIV. The median time since transplant receipt was 2.2 yr. No severe AEs or rejection was attributed to vaccination. The HD group reported more tenderness and local reactions, fatigue, and body ache when compared to the SD cohort, but these were considered mild and resolved within three days. Subjects in the HD group demonstrated a higher percentage of four-fold titer rise to H3N2 compared to the SD group. HD influenza vaccine was well tolerated and may have increased immunogenicity. A phase 2 trial is needed to confirm.