A review of guidance on immunization in persons with defective or deficient splenic function

Impaired IgM Memory B Cell Function Is Common in Coeliac Disease but Conjugate Pneumococcal Vaccination Induces Robust Protective Immunity

Coeliac disease (CD) is associated with hyposplenism, an acquired impairment of spleen function associated with reduced IgM memory B cells and increased susceptibility to serious pneumococcal infection. Little is known about the immune implications of hyposplenism in CD or the optimal pneumococcal vaccination strategy. In this study, the immune effects of hyposplenism in CD, and the accuracy of screening approaches and protective responses induced by two different pneumococcal vaccines were examined. Active and treated CD cohorts, and healthy and surgically splenectomised controls underwent testing for the presence of Howell-Jolly bodies and pitted red cells, spleen ultrasound, and immune assessment of IgM memory B cell frequency and IgM memory B cell responses to T cell-dependent (TD) or T cell-independent (TI) stimulation. Responses following conjugate (TD) and polysaccharide (TI) pneumococcal vaccination were compared using ELISA and opsonophagocytic assays. Although hyposplenism is rare in treated CD (5.1%), functional B cell defects are common (28-61%) and are not detected by current clinical tests. Conjugate pneumococcal vaccination induced superior and sustained protection against clinically relevant serotypes. Clinical practice guidelines in CD should recommend routine pneumococcal vaccination, ideally with a conjugate vaccine, of all patients in lieu of hyposplenism screening.

A young man with acute abdomen and anaemia

A young man was hospitalised with acute abdomen and signs of pancreatitis. He became seriously ill and required surgery to address the underlying cause.

Adherence to vaccination guidelines of patients with complete splenectomy in Norway, 2008-2020

The spleen is responsible for blood filtration and mounting an immune response against pathogens. In some people the spleen must be surgically removed because of traumatic events or oncological and hematological conditions. These patients are at higher risk of developing diseases caused by encapsulated bacteria throughout their lives. Thus, immunisations are advised for splenectomised persons to prevent infection caused by Streptococcus pneumoniae, Neisseria meningitidis and Haemophilus influenzae type b (Hib). This study assessed vaccination coverage (VC) among Norwegian patients with surgical asplenia. Using the Nomesco Classification of Surgical Procedures codes, patient information (age, sex, date of initial diagnosis and date of surgery) was acquired from the Norwegian Patient Registry. The National Immunization Register provided information on vaccination status and data of any subsequent invasive bacterial infections were obtained from the Norwegian Surveillance System for Communicable Diseases. From the total population of Norway, 3155 patients who had undergone complete splenectomy were identified. Of these, 914 (29.0%) had received at least one dose of pneumococcal conjugate vaccine (PCV), 1324 (42.0%) at least one dose of pneumococcal polysaccharide vaccine and 589 (18.7%) had received both. Only 4.2% of the patients had received two doses of a meningococcal ACWY conjugate vaccine, while 8.0% of 1467 patients splenectomised after 2014 had received at least two doses of a serogroup B meningococcal vaccine. The VC for Hib was 18.7%. Nearly all splenectomised children under the age of 10 were vaccinated with Hib and PCV as these vaccines are included in the childhood immunisation program. For all vaccines, VC decreased with age. Twenty-nine invasive bacterial infections were registered post-splenectomy in 25 patients. Vaccination according to national recommendations could have prevented at least 8 (28%) of these infections. Our study showed that efforts are required to increase VC of splenectomised individuals in Norway.

Prise en charge d’un patient drépanocytaire aux urgences

La drépanocytose est aujourd’hui la première maladie génétique en France avec environ 30 000 patients adultes. Une mutation ponctuelle sur le chromosome 11 conduit à la production d’une hémoglobine pathologique qui polymérise sous l’effet de facteurs endo-ou exogènes induisant la falciformation des globules rouges à l’origine d’une vasoocclusion artérielle dont une des conséquences est l’oblitération des vaisseaux à destinée osseuse. Les infarctus osseux sont particulièrement douloureux, conduisant les patients aux urgences où l’enjeu est de soulager rapidement les douleurs par l’utilisation de morphine principalement par analgésie autocontrôlée après titration morphinique. Le risque majeur au cours de ces crises vaso-occlusives (CVO) est l’apparition d’un syndrome thoracique aigu (STA) pouvant mettre en jeu le pronostic vital du patient. La spirométrie incitative est un moyen préventif du STA important à instituer dès les urgences. Une antibiothérapie sera mise en place en cas de fièvre chez ces patients aspléniques à risque d’infections à germes encapsulés notamment par le pneumocoque. L’échange transfusionnel est une des pierres angulaires du traitement des CVO ou du STA mais le risque d’accident hémolytique aigu post transfusionnel doit en limiter l’usage à des situations mettant en jeu le pronostic vital ou fonctionnel d’organe. Plusieurs scores clinicobiologiques permettent de décider de l’utilité d’un angioscanner thoracique au cours du STA à la recherche d’une embolie pulmonaire ou pour décider de la pertinence d’une sortie vers une hospitalisation à domicile (Programme DREPADOM). L’utilisation de la morphine en dehors de l’hôpital de façon prolongée doit être prudente en raison du risque d’addiction.

Immunization coverage among asplenic patients and strategies to increase vaccination compliance: a systematic review and meta-analysis

BACKGROUND

Asplenic or splenectomized patients have a higher risk (ranging from 10 to 50-fold) than the general population of developing an overwhelming post-splenectomy infection (OPSI). Thus, they should receive specific vaccinations to prevent bacterial infections and influenza. The aim of this meta-analysis was to estimate vaccination coverage (VC) with the recommended vaccines among splenectomized patients; strategies recommended in those studies to improve VC worldwide are considered as well.

RESEARCH DESIGN AND METHODS

Scopus, MEDLINE/PubMed, Google Scholar and ISI Web of Knowledge databases were searched. Research papers, short reports, reviews, and meta-analyses published between January 1, 2010 and July 18, 2020 were included; no geographic restrictions were included. Twenty-four studies were included in the meta-analysis.

RESULTS

For anti-pneumococcal vaccination, coverage was 55.1% (95%CI = 41.0-69.2%), for anti-Hib 48.3% (95%CI = 34.3-52.3%), for anti-meningococcal C/ACYW135 33.7% (95%CI = 23.6-43.9%), for anti-meningococcal B 13.3% (95%CI = 7.0-19.5%) and for anti-influenza 53.2% (95%CI = 22.0-84.4%). Most studies determined a lack of adherence to international guidelines by healthcare workers and suggested the need to better educate health professionals in the management of post-splenectomy patients.

CONCLUSIONS

The meta-analysis showed the suboptimal immunization coverage for the vaccines recommended for asplenic patients. Greater efforts must be made by public health professionals to increase VC in this group of patients at risk. Introducing specific prophylaxis protocols in the clinical routine seems to guarantee better immunization compliance in those patients.

Hyposplenism, Hashimoto's Autoimmune Thyroiditis and Overlap Syndrome (Celiac Disease and Autoimmune Hepatitis Type 1)

Hyposplenism is associated with autoimmune diseases, inflammatory bowel disease, severe celiac disease, autoimmune thyroiditis, untreated HIV infection and chronic graft-versus-host disease. The aim of this study was to review the existing data on hyposplenism associated with celiac disease and Hashimoto's autoimmune thyroiditis. Our research was based on a clinical case concerning a 41-year-old female who presented with asthenia, fatigue, dyspepsia and chronic diarrhea. The medical history revealed autoimmune Hashimoto's thyroiditis, type 2 diabetes, fatty liver disease, chronic gastritis and thrombocytosis. Multiple investigations showed hyposplenism and complex autoimmune dysfunction with positive serum markers for celiac disease and type 1 autoimmune hepatitis along with minor symptomatology. The intestinal symptomatology of celiac disease is often hid by hypothyroidism-associated autoimmune thyroiditis. Asymptomatic or minimally symptomatic celiac disease associated with Hashimoto's autoimmune thyroiditis is diagnosed by biomarkers. Hyposplenism in celiac disease can occur regardless of the disease stage, latent or symptomatic.

OMIC Technologies and Vaccine Development: From the Identification of Vulnerable Individuals to the Formulation of Invulnerable Vaccines

Routine vaccination is among the most effective clinical interventions to prevent diseases as it is estimated to save over 3 million lives every year. However, the full potential of global immunization programs is not realised because population coverage is still suboptimal. This is also due to the inadequate immune response and paucity of informative correlates of protection upon immunization of vulnerable individuals such as newborns, preterm infants, pregnant women, and elderly individuals as well as those patients affected by chronic and immune compromising medical conditions. In addition, these groups are undervaccinated for a number of reasons, including lack of awareness of vaccine-preventable diseases and uncertainty or misconceptions about the safety and efficacy of vaccination by parents and healthcare providers. The presence of these nonresponders/undervaccinated individuals represents a major health and economic burden to society, which will become particularly difficult to address in settings with limited public resources. This review describes innovative and experimental approaches that can help identify specific genomic profiles defining nonresponder individuals for whom specific interventions might be needed. We will provide examples that show how such information can be useful to identify novel biomarkers of safety and immunogenicity for future vaccine trials. Finally, we will discuss how system biology “OMICs” data can be used to design bioinformatic tools to predict the vaccination outcome providing genetic and molecular “signatures” of protective immune response. This strategy may soon enable identification of signatures highly predictive of vaccine safety, immunogenicity, and efficacy/protection thereby informing personalized vaccine interventions in vulnerable populations.

A cohort study to evaluate infection prevention protocol in pediatric trauma patients with blunt splenic injury in a Dutch level 1 trauma center

PURPOSE

Asplenic patients are at increased risk for the development of overwhelming postsplenectomy infection (OPSI) syndrome. It is believed that adequate immunization, antimicrobial prophylaxis, as well as appropriate education concerning risks on severe infection lead to the decreased incidence of OPSI. The aim of this study was to analyze the methods used to prevent OPSI in trauma patients splenectomized before the age of 18.

PATIENTS AND METHODS

A retrospective, single-center study of all pediatric patients sustaining blunt splenic injury (BSI) managed at our level 1 trauma center from January 1979 to March 2012 was performed. A questionnaire was sent to all the included patients to determine the level of knowledge concerning infection risks, the use of antibiotics, and compliance to vaccination recommendations. Furthermore, we investigated whether the implementation of guidelines in 2003 and 2011 resulted in higher vaccination rates.

RESULTS

We included 116 children with BSI. A total of 93 completed interviews were eligible for analysis, resulting in a total response rate of 80% and 1,116 patient years. Twenty-seven patients were splenectomized, and 66 patients were treated by a spleen preserving therapy (including embolization). Only two out of 27 splenectomized patients were adequately vaccinated, five patients without a spleen used prophylactic antibiotics, and about half of the asplenic patients had adequate knowledge of the risk that asplenia entails. A total of 22/27 splenectomized patients were neither adequately vaccinated nor received prophylactic antibiotics. There was no OPSI seen in our study population during the 1,116 follow-up years.

CONCLUSION

The vaccination status, the level of knowledge concerning prevention of an OPSI, and the use of prophylactic antibiotics are suboptimal in pediatric patients treated for BSI. Therefore, we created a new follow-up treatment guideline to have adequate preventive coverage to current standards for these patients.

Vaccination coverage and mortality after splenectomy: results from an Italian single-centre study

Splenectomy is a well-recognised risk factor for life-threatening overwhelming post-splenectomy infection (OPSI). To prevent OPSI, immunisations against encapsulated bacteria (S. pneumoniae, N. meningitidis, H. influenzae) and influenza virus are recommended. However, there is still a lack of uniformity and poor compliance with these recommendations. Following a local physicians' awareness campaign regarding the importance of vaccine prophylaxis of splenectomised patients, we aimed to register vaccination coverage, mortality and infection rates in all patients who underwent splenectomy at our hospital, over a six-year time span. Reasons for splenectomy, patients' compliance with vaccinations, mortality and infectious events were recorded. The reasons for splenectomy in the 216 identified patients (mean age 58.2 ± 14; M:F ratio 1.4:1) were haematologic disorders (38.8%), solid tumours (28.7%), traumatic rupture (22.7%) and other causes (9.7%). A total of 146 patients (67.6%) received at least one of the four vaccines. Overall, the mortality rate was significantly greater in unvaccinated compared to vaccinated patients (p < 0.001), although after the adjustment for the cause of splenectomy the statistical significance was lost (p = 0.085) due to the burden of solid tumour-related mortality. Among the 21 reported cases of OPSI, eight were fatal and five were potentially vaccine-preventable. Our results show that two-thirds of splenectomised patients comply with vaccine prophylaxis. Future interventional studies or ad hoc registries might overcome barriers to vaccination or intentional non-compliance.

Atypical Hemolytic Uremic Syndrome: A Brief Review

Atypical hemolytic uremic syndrome (aHUS) is a disease characterized by the triad of microangiopathic hemolytic anemia, thrombocytopenia and acute kidney injury. The histopathologic lesions of aHUS include thrombotic microangiopathy involving the glomerular capillaries and thrombosis involving arterioles or interlobar arteries. Extra-renal manifestations occur in up to 20% of patients. The majority of aHUS is caused by complement system defects impairing ordinary regulatory mechanisms. Activating events therefore lead to unbridled, ongoing complement activity producing widespread endothelial injury. Pathologic mutations include those resulting in loss-of-function in a complement regulatory gene (CFH, CFI, CD46 or THBD) or gain-of-function in an effector gene (CFB or C3). Treatment with the late complement inhibitor, eculizumab – a monoclonal antibody directed against C5 – is effective.

Vaccination of special populations: Protecting the vulnerable

One of the strategic objectives of the 2011-2020 Global Vaccine Action Plan is for the benefits of immunisation to be equitably extended to all people. This approach encompasses special groups at increased risk of vaccine-preventable diseases, such as preterm infants and pregnant women, as well as those with chronic and immune-compromising medical conditions or at increased risk of disease due to immunosenescence. Despite demonstrations of effectiveness and safety, vaccine uptake in these special groups is frequently lower than expected, even in developed countries with vaccination strategies in place. For example, uptake of the influenza vaccine in pregnancy rarely exceeds 50% in developed countries and, although data are scarce, it appears that only half of preterm infants are up-to-date with routine paediatric vaccinations. Many people with chronic medical conditions or who are immunocompromised due to disease or aging are also under-vaccinated. In the US, coverage among people aged 65years or older was 67% for the influenza vaccine in the 2014-2015 season and 55-60% for tetanus and pneumococcal vaccines in 2013, while the coverage rate for herpes zoster vaccination among those aged 60years or older was only 24%. In most other countries, rates are far lower. Reasons for under-vaccination of special groups include fear of adverse outcomes or illness caused by the vaccine, the inconvenience (and in some settings, cost) of vaccination and lack of awareness of the need for vaccination or national recommendations. There is also evidence that healthcare providers' attitudes towards vaccination are among the most important influences on the decision to vaccinate. It is clear that physicians' adherence to recommendations needs to be improved, particularly where patients receive care from multiple subspecialists and receive little or no care from primary care providers.

Total versus partial splenectomy in pediatric hereditary spherocytosis: A systematic review and meta-analysis

To compare the clinical effectiveness of total splenectomy (TS) or partial splenectomy (PS) in pediatric hereditary spherocytosis, a systematic review and meta-analysis was performed (PROSPERO registration CRD42015030056). There were 14 observational studies comparing pre- and postoperative hematologic parameters. Secondary outcomes include in-hospital infections, surgical complications, symptomatic recurrence, and biliary disease. TS is more effective than PS to increase hemoglobin (3.6 g/dl vs. 2.2 g/dl) and reduce reticulocytes (12.5% vs. 6.5%) after 1 year; outcomes following PS are stable for at least 6 years. There were no cases of overwhelming postsplenectomy sepsis. A population-based patient registry is needed for long-term follow-up.

Alteration of lymphocyte phenotype and function in sickle cell anemia: Implications for vaccine responses

Individuals with sickle cell anemia (SCA) have increased susceptibility to infections, secondary to impairment of immune function. Besides the described dysfunction in innate immunity, including impaired opsonization and phagocytosis of bacteria, evidence of dysfunction of T and B lymphocytes in SCA has also been reported. This includes reduction in the proportion of circulating CD4+ and CD8+ T cells, reduction of CD4+ helper: CD8+ suppressor T cell ratio, aberrant activation and dysfunction of regulatory T cells (Treg ), skewing of CD4+ T cells towards Th2 response and loss of IgM-secreting CD27 + IgM(high) IgD(low) memory B cells. These changes occur on the background of immune activation characterized by predominance of memory CD4+ T cell phenotypes, increased Th17 signaling and elevated levels of C-reactive protein and pro-inflammatory cytokines IL-6 and TNF-α, which may affect the immunogenicity and protective efficacy of vaccines available to prevent infections in SCA. Thus, in order to optimize the use of vaccines in SCA, a thorough understanding of T and B lymphocyte functions and vaccine reactivity among individuals with SCA is needed. Studies should be encouraged of different SCA populations, including sub-Saharan Africa where the burden of SCA is highest. This article summarizes our current understanding of lymphocyte biology in SCA, and highlights areas that warrant future research. Am. J. Hematol. 91:938-946, 2016. © 2016 Wiley Periodicals, Inc.

Splenic marginal zone lymphoma: from genetics to management

Splenic marginal zone lymphoma (SMZL) is a rare B-cell malignancy involving the spleen, bone marrow, and frequently the blood. SMZL lymphomagenesis involves antigen and/or superantigen stimulation and molecular deregulation of genes (NOTCH2 and KLF2) involved in the physiological differentiation of spleen marginal zone B cells. Diagnosis requires either spleen histology or, alternatively, the documentation of a typical cell morphology and immunophenotype on blood cells coupled with the detection of intrasinusoidal infiltration by CD20+ cells in the bone marrow. Among B-cell tumors, deletion of 7q and NOTCH2 mutations are almost specific lesions of SMZL, thus representing promising diagnostic biomarkers of this lymphoma. Although the majority of SMZLs show an indolent course with a median survival of approximately 10 years, nearly 30% of patients experience a poor outcome. No randomized trials are reported for SMZL, and few prospective trials are available. A watch-and-wait approach is advisable for asymptomatic patients. Treatment options for symptomatic patients ranges from splenectomy to rituximab alone or combined with chemotherapy. In some geographic areas, a subset of patients with SMZL associates with hepatitis C virus infection, prompting virus eradication as an effective lymphoma treatment. It would be worthwhile to explore deregulated cellular programs of SMZL as therapeutic targets in the future; improved clinical and biological prognostication will be essential for identifying patients who may benefit from novel approaches.

Vaccine-preventable infections in Systemic Lupus Erythematosus

Systemic Lupus Erythematosus (SLE) is characterized by abnormal autoantibody production and clearance. Infections are among the most important causes of morbidity and mortality in SLE patients; they have an increased frequency of severe bacterial and viral infections possibly due to inherited genetic and immunologic defects and to immunosuppressive therapies. In addition, infectious agents can switch on lupus disease expression and activity. Among the strategies to reduce the risk of infection, vaccination can be considered the most reliable option. Most vaccines are effective and safe in SLE patients, although in certain cases immunogenicity may be sub-optimal and vaccination can trigger a flare. Although these issues are currently unresolved, the risk benefit balance is in favor for vaccination to reduce the risk of infection in SLE patients. In the present review we discuss the preventive strategies currently recommended to reduce bacterial and viral infections in SLE.