Immunogenicity of virosomal adjuvanted trivalent influenza vaccination in allogeneic stem cell transplant recipients

Immunogenicity and safety of the BNT162b2 mRNA COVID-19 vaccine in haematopoietic stem cell transplantation recipients

The immunogenicity and safety of Pfizer‐BioNTech BNT162b2 mRNA vaccine in allogeneic haematopoietic stem cell transplantation (HSCT) recipients are unknown. We prospectively followed 152 HSCT recipients who were at least six months following transplantation and with no active acute graft‐versus‐host disease (GVHD). Blood samples were taken 2–4 weeks after the second vaccination and analyzed for receptor‐binding domain (RBD) antibodies and neutralizing antibodies (NA). 272 immunocompetent healthcare workers served as controls. At a median of 28 days after the second vaccination, 118 patients (77·6%) developed RBD immunoglobulin G (IgG) with a geometric mean titre (GMT) of 2·61 [95% CI (confidence interval), 2·16–3·16]. In the control group 269/272 (98·9%) developed RBD IgG, with a GMT of 5·98 (95% CI 5·70–6·28), P < 0·0001. The GMT of NA in HSCT recipients and controls was 116·0 (95% CI 76·5–175·9), and 427·9 (95% CI 354·3–516·7) respectively (P < 0001). Multivariate logistic regression analysis revealed that HSCT recipients with no chronic GVHD and no immunosuppressive therapy at the time of vaccination had significantly higher levels of NA following the second vaccination. Adverse events were minimal and were less common than in healthy controls. In conclusion; the BNT162b2 mRNA vaccination is safe and effective in HSCT recipients, especially those who are immunosuppression‐free. A significant fraction developed protecting NA.

Influenza vaccination in immunocompromised populations: Strategies to improve immunogenicity

Immunocompromised individuals are at high risk of severe illness and complications from influenza infection. For this reason, immunization using inactivated influenza vaccines is recommended for transplant patients, individuals receiving immunosuppressant treatments, and other persons with immunodeficiency. However, these immunocompromised populations are more likely to have lower and non-protective responses to annual vaccination with a standard influenza vaccine. Here, we review strategies aimed to improve the immunogenicity of influenza vaccines in immunocompromised populations. The different strategies employed have included adjuvanted vaccines, high-dose vaccines, booster doses, intradermal vaccination, and temporary discontinuation of immunosuppressant treatment regimens. High-dose trivalent, inactivated, split-virus influenza vaccine (IIV3-HD) is so far one of the leading strategies for improving vaccine responses in HIV patients, transplant patients, and persons receiving immunosuppressant therapies for inflammatory diseases. Several studies in these populations have shown stronger humoral responses with IIV3-HD than existing standard-dose trivalent vaccine, and comparable safety. Accordingly, some scientific societies have stated that high-dose influenza vaccine could be a preferred option for immunocompromised patients. However, larger randomized controlled studies are needed to validate relative immunogenicity and safety of IIV3-HD and other enhanced vaccines and vaccination strategies in immunocompromised individuals.

Clinical Effectiveness of Influenza Vaccination After Allogeneic Hematopoietic Stem Cell Transplantation: A Cross-sectional, Prospective, Observational Study

BACKGROUND

Vaccination is the primary method for preventing influenza respiratory virus infection (RVI). Although the influenza vaccine is able to achieve serological responses in some allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients, its clinical benefits are still uncertain.

METHODS

In this prospective, cross-sectional study, we retrospectively analyzed the effect of inactivated trivalent influenza vaccination on the prevalence of influenza RVI in a consecutive cohort of 136 allo-HSCT adult recipients who developed 161 RVI over 5 flu seasons (from 2013 to 2018). Respiratory viruses in upper- and/or lower-respiratory tract specimens were tested using multiplex polymerase chain reaction panel assays.

RESULTS

Overall, we diagnosed 74 episodes (46%) of influenza RVI in 70 allo-HSCT recipients. Influenza RVI occurred in 51% of the non-vaccinated compared to 36% of the vaccinated recipients (P = .036). A multivariate analysis showed that influenza vaccination was associated with a lower prevalence of influenza RVI (odds ratio [OR] 0.39, P = .01). A multivariate risk factor analysis of lower-respiratory tract disease (LRTD) identified 2 conditions associated with the probability of influenza RVI progression: influenza vaccination (OR 0.12, 95% confidence interval [CI] 0.014-1, P = .05) and a high-risk immunodeficiency score (OR 36, 95% CI 2.26-575, P = .011). Influenza vaccination was also associated with a lower likelihood of an influenza-related hospital admission (14% vs 2%, P = .04).

CONCLUSIONS

This study shows that influenza vaccination may have a clinical benefit in allo-HSCT recipients with virologically-confirmed RVI, in terms of a lower influenza RVI prevalence, slower LRTD progression, and lower likelihood of hospital admission.

Pathogen-Specific T Cells Beyond CMV, EBV and Adenovirus

PURPOSE OF REVIEW

Infectious diseases contribute significantly to morbidity and mortality in recipients of allogeneic haematopoietic stem cell transplantation (aHSCT), particularly in the era of highly immunosuppressive transplant regimens and alternate donor transplants. Delayed cellular immune recovery is a major mechanism for the increased risk in these patients. Adoptive cell therapy with ex vivo manipulated pathogen-specific T cells (PSTs) is increasingly taking its place as a treatment strategy using donor-derived or third party-banked cells.

RECENT FINDINGS

The majority of clinical trial data in the form of early-phase studies has been in the prophylaxis or treatment of cytomegalovirus (CMV), Epstein-Barr virus (EBV) and adenovirus (AdV). Advancements in methods to select and enrich PSTs offer the opportunity to target the less common viral pathogens as well as fungi with this technology. Early clinical studies of PSTs targeting polyomaviruses (BK virus and JC virus), human herpesvirus 6 (HHV6), varicella zoster virus (VZV) and Aspergillus spp. have shown promising results in small numbers of patients. Other potential targets include herpes simplex virus (HSV), respiratory viruses and other invasive fungal species. In this review, we describe the burden of disease of this wider spectrum of pathogens, the progress in the development of manufacturing capability, early clinical results and the opportunities and challenges for implementation in the clinic.

Analysis of MarketScan Data for Immunosuppressive Conditions and Hospitalizations for Acute Respiratory Illness, United States

Increasing use of immunosuppressive biologic therapies poses a challenge for infectious diseases. Immunosuppressed patients have a high risk for influenza complications and an impaired immune response to vaccines. The total burden of immunosuppressive conditions in the United States, including those receiving emerging biologic therapies, remains unknown. We used the national claims database MarketScan to estimate the prevalence of immunosuppressive conditions and risk for acute respiratory illnesses (ARIs). We studied 47.2 million unique enrollees, representing 115 million person-years of observation during 2012–2017, and identified immunosuppressive conditions in 6.2% adults 18–64 years of age and 2.6% of children <18 years of age. Among 542,105 ARI hospitalizations, 32% of patients had immunosuppressive conditions. The risk for ARI hospitalizations was higher among enrollees with immunosuppression than among nonimmunosuppressed enrollees. Future efforts should focus on developing improved strategies, including vaccines, for preventing influenza in immunosuppressed patients, who are an increasing population in the United States.

Revisiting Role of Vaccinations in Donors, Transplant Recipients, Immunocompromised Hosts, Travelers, and Household Contacts of Stem Cell Transplant Recipients

Vaccination is an effective strategy to prevent infections in immunocompromised hematopoietic stem cell transplant recipients. Pretransplant vaccination of influenza, pneumococcus, Haemophilus influenza type b, diphtheria, tetanus, and hepatitis B, both in donors and transplant recipients, produces high antibody titers in patients compared with recipient vaccination only. Because transplant recipients are immunocompromised, live vaccines should be avoided with few exceptions. Transplant recipients should get inactive vaccinations when possible to prevent infection. This includes vaccination against influenza, pneumococcus, H. influenza type b, diphtheria, tetanus, pertussis, meningococcus, measles, mumps, rubella, polio, hepatitis A, human papillomavirus, and hepatitis B. Close contacts of transplant recipients can safely get vaccinations (inactive and few live vaccines) as per their need and schedule. Transplant recipients who wish to travel may need to get vaccinated against endemic diseases that are prevalent in such areas. There is paucity of data on the role of vaccinations for patients receiving novel immunotherapy such as bispecific antibodies and chimeric antigen receptor T cells despite data on prolonged B cell depletion and higher risk of opportunistic infections.

Respiratory Virus Infections of the Stem Cell Transplant Recipient and the Hematologic Malignancy Patient

Respiratory virus infections in hematologic stem cell transplant recipients and patients with hematologic malignancies are increasingly recognized as a cause of significant morbidity and mortality. The often overlapping clinical presentation makes molecular diagnostic strategies imperative for rapid diagnosis and to inform understanding of the changing epidemiology of each of the respiratory viruses. Most respiratory virus infections are managed with supportive therapy, although there is effective antiviral therapy for influenza. The primary focus should remain on primary prevention infection control procedures and isolation precautions, avoidance of ill contacts, and vaccination for influenza.

Vaccination of haemopoietic stem cell transplant recipients: guidelines of the 2017 European Conference on Infections in Leukaemia (ECIL 7)

Infection is a main concern after haemopoietic stem cell transplantation (HSCT) and a major cause of transplant-related mortality. Some of these infections are preventable by vaccination. Most HSCT recipients lose their immunity to various pathogens as soon as the first months after transplant, irrespective of the pre-transplant donor or recipient vaccinations. Vaccination with inactivated vaccines is safe after transplantation and is an effective way to reinstate protection from various pathogens (eg, influenza virus and Streptococcus pneumoniae), especially for pathogens whose risk of infection is increased by the transplant procedure. The response to vaccines in patients with transplants is usually lower than that in healthy individuals of the same age during the first months or years after transplant, but it improves over time to become close to normal 2-3 years after the procedure. However, because immunogenic vaccines have been found to induce a response in a substantial proportion of the patients as early as 3 months after transplant, we recommend to start crucial vaccinations with inactivated vaccines from 3 months after transplant, irrespectively of whether the patient has or has not developed graft-versus-host disease (GvHD) or received immunosuppressants. Patients with GvHD have higher risk of infection and are likely to benefit from vaccination. Another challenge is to provide HSCT recipients the same level of vaccine protection as healthy individuals of the same age in a given country. The use of live attenuated vaccines should be limited to specific situations because of the risk of vaccine-induced disease.

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.

Influenza vaccines in immunosuppressed adults with cancer

BACKGROUND

This is an update of the Cochrane review published in 2013, Issue 10.Immunosuppressed cancer patients are at increased risk of serious influenza-related complications. Guidelines, therefore, recommend influenza vaccination for these patients. However, data on vaccine effectiveness in this population are lacking, and the value of vaccination in this population remains unclear.

OBJECTIVES

To assess the effectiveness of influenza vaccine in immunosuppressed adults with malignancies. The primary review outcome is all-cause mortality, preferably at the end of the influenza season. Influenza-like illness (ILI, a clinical definition), confirmed influenza, pneumonia, any hospitalisations, influenza-related mortality and immunogenicity were defined as secondary outcomes.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase and LILACS databases up to May 2017. We searched the following conference proceedings: ICAAC, ECCMID, IDSA (infectious disease conferences), ASH, ASBMT, EBMT (haematological), and ASCO (oncological) between the years 2006 to 2017. In addition, we scanned the references of all identified studies and pertinent reviews. We searched the websites of the manufacturers of influenza vaccine. Finally, we searched for ongoing or unpublished trials in clinical trial registry databases.

SELECTION CRITERIA

Randomised controlled trials (RCTs), prospective and retrospective cohort studies and case-control studies were considered, comparing inactivated influenza vaccines versus placebo, no vaccination or a different vaccine, in adults (16 years and over) with cancer. We considered solid malignancies treated with chemotherapy, haematological cancer patients treated or not treated with chemotherapy, cancer patients post-autologous (up to six months after transplantation) or allogeneic (at any time) haematopoietic stem cell transplantation (HSCT).

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the risk of bias and extracted data from included studies adhering to Cochrane methodology. Meta-analysis could not be performed because of different outcome and denominator definitions in the included studies.

MAIN RESULTS

We identified six studies with a total of 2275 participants: five studies comparing vaccination with no vaccination, and one comparing adjuvanted vaccine with non-adjuvanted vaccine. Three studies were RCTs, one was a prospective observational cohort study and two were retrospective cohort studies.For the comparison of vaccination with no vaccination we included two RCTs and three observational studies, including 2202 participants. One study reported results in person-years while the others reported results per person. The five studies were performed between 1993 and 2015 and included adults with haematological diseases (three studies), patients following bone marrow transplantation (BMT) (two studies) and solid malignancies (three studies).One RCT and two observational studies reported all-cause mortality; the RCT showed similar mortality rates in both arms (odds ratio (OR) 1.25 (95% CI 0.43 to 3.62; 1 study, 78 participants, low-certainty evidence)); and the observational studies demonstrated a significant association between vaccine receipt and lower risk of death, adjusted hazard ratio 0.88 (95% CI 0.78 to 1; 1 study, 1577 participants, very low-certainty evidence) in one study and OR 0.42 (95% CI 0.24 to 0.75; 1 study, 806 participants, very low-certainty evidence) in the other. One RCT reported a reduction in ILI with vaccination, while no difference was observed in one observational study. Confirmed influenza rates were lower with vaccination in one RCT and the three observational studies, the difference reaching statistical significance in one. Pneumonia was observed significantly less frequently with vaccination in one observational study, but no difference was detected in another or in the RCT. One RCT showed a reduction in hospitalisations following vaccination, while an observational study found no difference. No life-threatening or persistent adverse effects from vaccination were reported. The strength of evidence was limited by the low number of included studies and by their low methodological quality and the certainty of the evidence for the mortality outcome according to GRADE was low to very low.For the comparison of adjuvanted vaccine with non-adjuvanted vaccine, we identified one RCT, including 73 patients. No differences were found for the primary and all secondary outcomes assessed. Mortality risk ratio was 0.54 (95% CI 0.05 to 5.73; low-certainty evidence) in the adjuvanted vaccine group. The quality of evidence was low due to the small sample size and the large confidence intervals for all outcomes.

AUTHORS' CONCLUSIONS

Observational data suggest lower mortality and infection-related outcomes with influenza vaccination. The strength of evidence is limited by the small number of studies and low grade of evidence. It seems that the evidence, although weak, shows that the benefits overweigh the potential risks when vaccinating adults with cancer against influenza. However, additional placebo or no-treatment controlled RCTs of influenza vaccination among adults with cancer is ethically questionable.There is no conclusive evidence regarding the use of adjuvanted versus non-adjuvanted influenza vaccine in this population.

Vaccinations in patients with hematological malignancies

Patients with hematological malignancies are at risk for a number of infections that are potentially preventable by vaccinations such as pneumococcal infections and influenza. Treatment, especially with anti-B-cell antibodies and hematopoietic stem cell transplantation (HSCT), negatively impacts the response to vaccination for several months. It is therefore recommended that patients be vaccinated before initiating immunosuppressive therapy if possible. The risk of side-effects with inactivated vaccines is low, but care has to be taken with live vaccines, such as varicella-zoster virus vaccine, since severe and fatal complications have been reported. HSCT patients require repeated doses of most vaccines to achieve long-lasting immune responses. New therapeutic options for patients with hematological malignancies that are rapidly being introduced into clinical practice will require additional research regarding the efficacy of vaccinations. New vaccines are also in development that will require well-designed studies to ascertain efficacy and safety.