Risk of solid organ transplant rejection following vaccination with seasonal trivalent inactivated influenza vaccines in England: A self-controlled case-series

Tree-temporal scan statistics for safety signal detection in vaccine clinical trials

The evaluation of safety is critical in all clinical trials. However, the quantitative analysis of safety data in clinical trials poses statistical difficulties because of multiple potentially overlapping endpoints. Tree-temporal scan statistic approaches address this issue and have been widely employed in other data sources, but not to date in clinical trials. We evaluated the performance of three complementary scan statistical methods for routine quantitative safety signal detection: the self-controlled tree-temporal scan (SCTTS), a tree-temporal scan based on group comparison (BGTTS), and a log-rank based tree-temporal scan (LgRTTS). Each method was evaluated using data from two phase III clinical trials, and simulated data (simulation study). In the case study, the reference set was adverse events (AEs) in the Reference Safety Information of the evaluated vaccine. The SCTTS method had higher sensitivity than other methods, and after dose 1 detected 80 true positives (TP) with a positive predictive value (PPV) of 60%. The LgRTTS detected 49 TPs with 69% PPV. The BGTTS had 90% of PPV with 38 TPs. In the simulation study, with simulated reference sets of AEs, the SCTTS method had good sensitivity to detect transient effects. The LgRTTS method showed the best performance for the detection of persistent effects, with high sensitivity and expected probability of type I error. These three methods provide complementary approaches to safety signal detection in clinical trials or across clinical development programmes. All three methods formally adjust for multiple testing of large numbers of overlapping endpoints without being excessively conservative.

Immunogenicity of High-Dose Versus MF59-Adjuvanted Versus Standard Influenza Vaccine in Solid Organ Transplant Recipients: The Swiss/Spanish Trial in Solid Organ Transplantation on Prevention of Influenza (STOP-FLU Trial)

BACKGROUND

The immunogenicity of the standard influenza vaccine is reduced in solid-organ transplant (SOT) recipients, so new vaccination strategies are needed in this population.

METHODS

Adult SOT recipients from 9 transplant clinics in Switzerland and Spain were enrolled if they were >3 months after transplantation. Patients were randomized (1:1:1) to a MF59-adjuvanted or a high-dose vaccine (intervention), or a standard vaccine (control), with stratification by organ and time from transplant. The primary outcome was vaccine response rate, defined as a ≥4-fold increase of hemagglutination-inhibition titers to at least 1 vaccine strain at 28 days postvaccination. Secondary outcomes included polymerase chain reaction-confirmed influenza and vaccine reactogenicity.

RESULTS

A total of 619 patients were randomized, 616 received the assigned vaccines, and 598 had serum available for analysis of the primary endpoint (standard, n = 198; MF59-adjuvanted, n = 205; high-dose, n = 195 patients). Vaccine response rates were 42% (84/198) in the standard vaccine group, 60% (122/205) in the MF59-adjuvanted vaccine group, and 66% (129/195) in the high-dose vaccine group (difference in intervention vaccines vs standard vaccine, 0.20; 97.5% confidence interval [CI], .12-1); P < .001; difference in high-dose vs standard vaccine, 0.24 [95% CI, .16-1]; P < .001; difference in MF59-adjuvanted vs standard vaccine, 0.17 [97.5% CI, .08-1]; P < .001). Influenza occurred in 6% of the standard, 5% in the MF59-adjuvanted, and 7% in the high-dose vaccine groups. Vaccine-related adverse events occurred more frequently in the intervention vaccine groups, but most of the events were mild.

CONCLUSIONS

In SOT recipients, use of an MF59-adjuvanted or a high-dose influenza vaccine was safe and resulted in a higher vaccine response rate.

CLINICAL TRIALS REGISTRATION

Clinicaltrials.gov NCT03699839.

Differences in Responses of Immunosuppressed Kidney Transplant Patients to Moderna mRNA-1273 versus Pfizer-BioNTech

Immunosuppressed kidney transplant (KT) recipients produce a weaker response to COVID-19 vaccination than immunocompetent individuals. We tested antiviral IgG response in 99 KT recipients and 66 healthy volunteers who were vaccinated with mRNA-1273 Moderna or BNT162b2 Pfizer-BioNTech vaccines. A subgroup of participants had their peripheral blood leukocytes (PBLs) evaluated for the frequency of T helper 1 (Th1) cells producing IL-2, IFN-γ and/or TNF-α, and IL-10-producing T-regulatory 1 (Tr) cells. Among KT recipients, 45.8% had anti-SARS-CoV-2 IgG compared to 74.1% of healthy volunteers (p = 0.009); also, anti-viral IgG levels were lower in recipients than in volunteers (p = 0.001). In terms of non-responders (≤2000 U/mL IgG), Moderna's group had 10.8% and Pfizer-BioNTech's group had 34.3% of non-responders at 6 months (p = 0.023); similarly, 15.7% and 31.3% were non-responders in Moderna and Pfizer-BioNTech groups at 12 months, respectively (p = 0.067). There were no non-responders among controls. Healthy volunteers had higher Th1 levels than KT recipients, while Moderna produced a higher Th1 response than Pfizer-BioNTech. In contrast, the Pfizer-BioNTech vaccine induced a higher Tr1 response than the Moderna vaccine (p < 0.05); overall, IgG levels correlated with Th1(fTTNF-α)/Tr1(fTIL-10) ratios. We propose that the higher number of non-responders in the Pfizer-BioNTech group than the Moderna group was caused by a more potent activity of regulatory Tr1 cells in KT recipients vaccinated with the Pfizer-BioNTech vaccine.

Influenza and pneumococcal vaccination and COVID-19 in kidney transplant patients

BACKGROUND

This study aims to investigate the effect of recent influenza and pneumococcal vaccines' administration on the development of COVID-19 infection in kidney transplant recipients during the pandemic.

METHODS

The effect of influenza and pneumococcal vaccines on the clinical course of the disease in COVID-positive (COVID group, n: 105) and COVID-negative (control group, n: 127) recipients has been examined. The control group included patients with negative rRT-PCR test results. At the time of the study, no patient was vaccinated with COVID-19 vaccine. The patients' influenza and/or pneumococcal vaccination rates in 2019 and 2020 were determined. In 2019 and 2020, 32 and 33 people in the COVID-positive group and 61 and 54 people in the COVID-negative group had received influenza and/or pneumococcal vaccines, respectively. The median study follow-up times of the COVID-negative and COVID-positive groups were 13.04 and 8.31 months, respectively.

RESULTS

Compared with the COVID-negative group, the patients in the COVID-positive group were younger and had a longer post-transplant time. In addition, the rate of transplantation from a living donor and the rate of COVID positivity in family members were also higher. The influenza vaccination rates in the COVID negative group were significantly higher than the COVID-positive group in 2020 (23.8% vs 37%, p = 0.031). Multivariate logistic regression analysis revealed that the presence of COVID-19 in family members and lack of pneumococcal vaccination in 2020 increased the risk of being positive for COVID-19. There was no significant difference in the hospitalization rates, the need for dialysis and intensive care, the hospital stay, and the graft dysfunction in the COVID-positive patients with and without influenza and pneumococcal vaccines.

CONCLUSION

The observations made throughout this study suggest that influenza and pneumococcal vaccination in transplant patients may reduce the risk of COVID-19 disease and provide additional benefits during the pandemic period.

Vaccination for the Prevention of Infection among Immunocompromised Patients: A Concise Review of Recent Systematic Reviews

Vaccination is crucial for avoiding infection-associated morbidity and mortality among immunocompromised patients. However, immunocompromised patients respond less well to vaccinations compared to healthy people, and little is known about the relative efficacy of various vaccines among different immunocompromised states. A total of 54 systematic reviews (22 COVID-19; 32 non-COVID-19) published within the last 5 years in Pubmed® were reviewed. They demonstrated similar patterns within three seroconversion response categories: good (about >60% when compared to healthy controls), intermediate (~40−60%), and poor (about <40%). Good vaccine responses would be expected for patients with chronic kidney disease, human immunodeficiency virus infection (normal CD4 counts), immune-mediated inflammatory diseases, post-splenectomy states, and solid tumors. Intermediate vaccine responses would be expected for patients with anti-cytotoxic T-lymphocyte antigen-4 therapy, hematologic cancer, and human immunodeficiency virus infection (low CD4 counts). Poor vaccine responses would be expected for patients with B-cell-depleting agents (e.g., anti-CD20 therapy), hematopoietic stem-cell transplant, solid organ transplant, and liver cirrhosis. For all vaccine response categories, vaccination should be timed when patients are least immunosuppressed. For the intermediate and poor vaccine response categories, high-dose vaccine, revaccination when patients are less immunosuppressed, checking for seroconversion, additional booster doses, and long-acting monoclonal antibodies may be considered, supplemented by shielding measures.

Safety of Influenza Vaccination During Orthopaedic Surgery Hospitalizations

BACKGROUND

Despite national recommendations, influenza vaccination rates during hospitalizations remain low. Inpatient hospitalization for orthopaedic surgery remains a largely missed opportunity for vaccination. To address potential concerns regarding safety, we evaluated whether influenza vaccination during hospitalization for orthopaedic surgery increases evaluations for infection postdischarge because patients and clinicians often cite fear of this potential outcome.

METHODS

This was a retrospective cohort study that was conducted among patients of a large integrated healthcare organization aged ≥6 months who were hospitalized for an orthopaedic surgery (defined by International Classification of Diseases, Ninth Revision procedure codes) between September 1 and March 31 from 2011 to 2014. Using propensity score matching (1:1) to adjust for confounding, we assessed the association between influenza vaccination during an inpatient stay for orthopaedic surgery and rates of readmission, emergency department visits, outpatient visits, fever (temperature ≥38.0°C), and evaluations for infections less than 7 days postdischarge.

RESULTS

Overall, 2,395 hospitalizations with inpatient vaccination and 21,708 hospitalizations without inpatient vaccination were identified. Following successful balance of covariates (standardized difference <0.1 for all covariates) through 1:1 propensity score matching, we included 2,376 exposed patients and 2,376 unexposed patients in the matched analysis. In adjusted analyses, compared with those who were not vaccinated during hospitalization, those vaccinated during an inpatient stay for orthopaedic surgery had no statistically significant increase in readmission (relative risk [RR] = 1.00, 95% confidence interval [CI]: 0.75 to 1.34), emergency department visits (RR = 1.14, 95% CI: 0.93 to 1.41), fever (RR = 1.31, 95% CI: 0.81 to 2.12), or clinical workups for infection (RR = 1.08, 95% CI: 0.98 to 1.18). A marginally increased risk of outpatient visits in the 7 days postdischarge was detected (RR = 1.13, 95% CI: 1.02 to 1.26).

DISCUSSION

There was no evidence of a substantial increased risk of infection-related outcomes associated with influenza vaccination during hospitalization for orthopaedic surgery. Our data support the recommendation of vaccinating orthopaedic surgery patients against influenza perioperatively.

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.

Survey of Corneal Surgeons' Attitudes Regarding Keratoplasty Rejection Risk Associated With Vaccinations

PURPOSE

To investigate the attitudes and practice of corneal specialists if patients with keratoplasty sought advice regarding common vaccinations and risk for potential graft rejection.

METHODS

An online questionnaire was posted on the Kera-net listserv and the EuCornea Web site in early 2020. Attitudes toward vaccinations and keratoplasty were obtained. Decision making for common keratoplasty (endothelial keratoplasty, deep anterior lamellar keratoplasty, and penetrating keratoplasty) scenarios at early and late time points was explored regarding the herpes zoster and influenza vaccines.

RESULTS

There were 142 respondents: 51.1% (70/137) specifically advise their patients with keratoplasty to get all vaccinations; 19.7% (27/137) stated clinical experience of a vaccine-associated rejection episode; 42.2% (57/135) were unaware of any such cases; and 64% (27/42) of those concerned would recommend delay if within 3 months of transplant surgery, recent corneal infection, or a recent rejection episode. The 2245 total responses to 18 clinical scenarios demonstrated wide variability in management of grafts in the setting of vaccination. Generally, 45.9% would not alter management, 26.2% would increase frequency of topical steroids, and 22.2% would recommend delay to vaccinations. Increased concern was expressed with recent surgery, live zoster vaccine and higher-risk penetrating keratoplasty scenarios.

CONCLUSIONS

Nearly half of the respondents do not alter management in the setting of keratoplasty and zoster and/or influenza vaccinations. Anecdotal rejection episodes possibly associated with vaccinations were reported by some. Vaccine-related rejection has not been shown in higher-level research, but that has not eliminated clinical concerns. Prospective research into the true vaccine-related risks in keratoplasty is necessary if evidence-based management guidelines are to be developed or definitive reassurance provided.

COVID-19 vaccination in pediatric solid organ transplant recipients-Current state and future directions

BACKGROUND

Population-level COVID-19 immunization will play a key role in slowing down the SARS-CoV-2 pandemic on a global scale and protect the most at-risk individuals. Thanks to a formidable universal effort, several SARS-CoV-2 vaccines have been marketed less than a year since the first documented COVID-19 case, with promising safety, efficacy, and immunogenicity results in adults. As children were not included in the initial trials, no vaccine is currently approved for individuals <16 years of age. Similarly, immunosuppressed individuals, such as solid organ transplant recipients, were excluded from initial vaccine trials, limiting the understanding of vaccine immunogenicity and safety in this at-risk population. Thus, data regarding COVID-19 vaccination in pediatric solid organ transplantation recipients are currently lacking.

METHODS

Members of the International Pediatric Transplant Association review the current general status of COVID-19 vaccines focusing on pediatric-specific issues.

RESULTS

This review provides an overview of COVID-19 vaccines in pediatric SOT recipients and highlights the current paucity of data in both pediatric and transplant settings in terms of safety, immunogenicity, and clinical efficacy.

CONCLUSIONS

Vaccine trials including children and transplant recipients are underway and will be necessary to characterize COVID-19 vaccine safety, immunogenicity, and efficacy, which will determine potential future research directions.

Vaccination and their importance for lung transplant recipients in a COVID-19 world

INTRODUCTION

Lung transplant patients are immunocompromised because of the medication they receive to prevent rejection, and as a consequence are susceptible to (respiratory) infections. Adequate vaccination strategies, including COVID-19 vaccination, are therefore needed to minimize infection risks.

AREAS COVERED

The international vaccination guidelines for lung transplant patients are reviewed, including the data on immunogenicity and effectivity of the vaccines. The impact on response to vaccination of the various categories of immunosuppressive drugs, used in the posttransplant period, on response to vaccination is described. A number of immunosuppressive and/or anti-inflammatory drugs also is used for controlling the immunopathology of severe COVID-19. Current available COVID-19 vaccines, both mRNA or adenovirus based are recommended for lung transplant patients.

EXPERT OPINION

In order to improve survival and quality of life, infections of lung transplant patients should be prevented by vaccination. When possible, vaccination should start already during the pre-transplantation period when the patient is on the waiting list. Booster vaccinations should be given post-transplantation, but only when immunosuppression has been tapered. Vaccine design based on mRNA technology could allow the design of an array of vaccines against other respiratory viruses, offering a better protection for lung transplant patients.

Immunizations in Chronic Kidney Disease and Kidney Transplantation

PURPOSE OF REVIEW

Infection is a significant cause of morbidity and mortality in both patients with chronic kidney disease (CKD) and in recipients of a kidney transplant (KT). We review the current data in patients with CKD, on dialysis, and in KT recipients to provide further guidance for clinicians regarding vaccine optimization in this patient population.

RECENT FINDINGS

This patient population remains under-vaccinated and thus more vulnerable to vaccine-preventable illness. Despite diminished responses to immunization in this population, significant protection is generally achieved.

SUMMARY

Vaccines are an important preventative tool and offer protection against infection. In the setting of suboptimal and waning immunity in this patient population, future studies are indicated to determine optimal vaccination regimens.

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.

Editorial: COVID-19 immunology and organ transplantation

PURPOSE OF REVIEW

The aim of this study was to provide a critical appraisal of the literature on the effects of the COVID-19 pandemic on organ transplantation, with a specific focus on lung transplantation given the predominant pulmonary involvement of the virus.

RECENT FINDINGS

There was a significant decrease in lung transplant volumes during the first wave of the COVID-19 pandemic due to a combination of reduced availability of donors and an imbalance between waitlist additions and inactivations. SARS-CoV-2 infection was subsequently associated with an exuberant immune response that can lead to the development of postinfectious fibrotic lung disease. Few lung transplants have been performed in previously infected recipients and long-term outcomes remain unknown. Although the lung transplant volume rebounded during the second wave, it is unclear what the long-term effects of healthcare resource limitation and public health measures will have on transplant volumes in the future. Outcomes after SARS-CoV-2 infection in previous lung transplant recipients appear to be worse than the general public, and, although an immunosuppressed state likely contributes to these outcomes, whether immunosuppression should be altered in those exposed to or infected with SARS-CoV-2 remains unanswered in the absence of unequivocal data.

SUMMARY

The COVID-19 pandemic has presented a number of challenges for lung transplant programs across the globe. Multiple research questions remain to be answered in order to optimally manage lung transplant recipients in the context of this pandemic.

COVID-19 vaccination in our transplant recipients: The time is now

We are entering 2021 with an expanding and effective COVID-19 vaccine armamentarium. Recent interim results from COVID-19 vaccine trials, including more than 80,000 participants worldwide, demonstrate remarkable efficacy and low rate of serious adverse events. Based on experience with other vaccines in transplant recipients and knowing the risk of severe COVID-19 in this population, we believe that COVID-19 vaccines provide potential benefit with minimal risk. We strongly support and encourage COVID-19 vaccination of our transplant recipients.

Evaluation of Recombinant Herpes Zoster Vaccine for Primary Immunization of Varicella-seronegative Transplant Recipients

BACKGROUND

Immunization of VZV-seronegative solid organ transplant (SOT) patients using the live-attenuated varicella vaccine is generally contraindicated, leaving no widely applicable immunization option. The recombinant subunit herpes zoster vaccine (RZV) is indicated for VZV seropositive persons to prevent shingles but could potentially also protect VZV-seronegative persons against varicella. We performed a safety and immunogenicity evaluation of RZV in VZV-seronegative SOT recipients as an option for protection.

METHODS

VZV-seronegative adult SOT patients with no history of varicella/shingles vaccine or disease were given 2 doses of RZV vaccine 2-6 months apart. Blood was drawn prevaccination (V1), prior to the second dose (V2) and 4 weeks after second dose (V3). Humoral (anti-gE) and cell-mediated immunity was evaluated, with polyfunctional cells defined as cells producing ≥2 cytokines.

RESULTS

Among 31 eligible VZV-seronegative SOT patients screened, 23 were enrolled. Median age was 38 years and median time since transplant procedure was 38 years. The most frequent transplant types were liver (35%) and lung (30%). Median anti-gE levels significantly increased from V1 to V3 (p=0001) and V2 to V3 (p<0001), even though only 55% had a positive seroresponse. Median polyfunctional CD4 T-cells counts increased from V1 to V2 (54/10 vs 104/10 cells; p=0041), and from V2 to V3 (380/10; p=0002). Most adverse events were mild with no rejection episodes.

CONCLUSION

RZV was safe and elicited significant humoral and cellular responses in VZV-seronegative SOT patients, and has the potential to be considered as a preventive strategy against primary varicella.

Vaccinations in pediatric kidney transplant recipients

Pediatric kidney transplant (KT) candidates should be fully immunized according to routine childhood schedules using age-appropriate guidelines. Unfortunately, vaccination rates in KT candidates remain suboptimal. With the exception of influenza vaccine, vaccination after transplantation should be delayed 3-6 months to maximize immunogenicity. While most vaccinations in the KT recipient are administered by primary care physicians, there are specific schedule alterations in the cases of influenza, hepatitis B, pneumococcal, and meningococcal vaccinations; consequently, these vaccines are usually administered by transplant physicians. This article will focus on those deviations from the normal vaccine schedule important in the care of pediatric KT recipients. The article will also review human papillomavirus vaccine due to its special importance in cancer prevention. Live vaccines are generally contraindicated in KT recipients. However, we present a brief review of live vaccines in organ transplant recipients, as there is evidence that certain live virus vaccines may be safe and effective in select groups. Lastly, we review vaccination of pediatric KT recipients prior to international travel.

Safety of Influenza Vaccination Administered During Hospitalization

OBJECTIVE

To determine whether influenza vaccination during hospitalization increases health care utilization, fever, and infection evaluations postdischarge.

PATIENTS AND METHODS

This retrospective cohort study conducted at Kaiser Permanente Southern California included patients aged 6 months or older hospitalized in a Kaiser Permanente Southern California facility with admission and discharge dates between September 1 and March 31 of the following calendar year, from 2011 to 2014. All influenza vaccinations administered during the period of August 1 to April 30 for influenza seasons 2011-2012, 2012-2013, and 2013-2014 were identified. We compared the risk of outcomes of interest between those who received influenza vaccination during their hospitalization vs those who were never vaccinated that season or were vaccinated at other times using propensity score analyses with inverse probability of treatment weighting. Outcomes of interest included rates of outpatient and emergency department visits, readmissions, fever, and clinical laboratory evaluations for infection (urine, blood, and wound culture; complete blood cell count) in the 7 days following discharge.

RESULTS

We included in the study 290,149 hospitalizations among 255,737 patients. In adjusted analyses, we found no increased risk of readmissions (relative risk [RR], 0.88; 95% CI, 0.83-0.95), outpatient visits (RR, 0.97; 95% CI, 0.95-0.99), fever (RR, 0.80; 95% CI, 0.68-0.93), and clinical evaluations for infection (RR, 0.95; 95% CI, 0.92-0.98) among those vaccinated during hospitalization compared with those who were never vaccinated or were vaccinated at other times.

CONCLUSION

Our findings provide reassurance about the safety of influenza vaccination during hospitalization. Every contact with a health care professional, including during a hospitalization, is an opportunity to vaccinate.

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.

Seasonal influenza vaccine in immunocompromised persons

Immunocompromised persons are at high risk of complications from influenza infection. This population includes those with solid organ transplants, hematopoietic stem cell transplants, solid cancers and hematologic malignancy as well as those with autoimmune conditions receiving biologic therapies. In this review, we discuss the impact of influenza infection and evidence for vaccine effectiveness and immunogenicity. Overall, lower respiratory disease from influenza is common; however, vaccine immunogenicity is low. Despite this, in some populations, influenza vaccine has demonstrated effectiveness in reducing severe disease. Various strategies to improve influenza vaccine immunogenicity have been attempted including two vaccine doses in the same influenza season, intradermal, adjuvanted, and high-dose vaccines. The timing of influenza vaccine is also important to achieve optimal immunogenicity. Given the suboptimal immunogenicity, family members and healthcare professionals involved in the care of these populations should be vaccinated. Health care professional recommendation for vaccination is an important factor in vaccine coverage.

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.

Adjuvanted (AS03) A/H1N1 2009 Pandemic Influenza Vaccines and Solid Organ Transplant Rejection: Systematic Signal Evaluation and Lessons Learnt

Introduction

We investigated a signal of solid organ transplant (SOT) rejection after immunisation with (AS03) A/H1N1 2009 pandemic influenza vaccines.

Methods

Potential immunological mechanisms were reviewed and quantitative analyses were conducted. The feasibility of pharmacoepidemiological studies was explored.

Results

Overall results, including data from a pharmacoepidemiological study, support the safety of adjuvanted (AS03) pandemic influenza vaccination in SOT recipients. The regulatory commitment to evaluate the signal through a stepwise investigation was closed in 2014.

Conclusion

Lessons learned highlight the importance of investigating plausible biological mechanisms between vaccines and potentially associated adverse outcomes, and the importance of selecting appropriate study settings and designs for safety signal investigations.

Electronic supplementary material

The online version of this article (doi:10.1007/s40264-017-0532-3) contains supplementary material, which is available to authorized users.