The spleen filters blood cells and contributes to the immune defense. The red pulp clears the blood from altered red blood cells via its unique microcirculatory network ; while the white pulp is a secondary lymphoid organ, directly connected to the bloodstream, whose specificity is the defense against encapsulated bacteria through the production of "natural" IgM in the marginal zone. Various health conditions can cause acquired impairment of the splenic function (or hyposplenism) directly and/or through therapeutic splenectomy. Hypo/asplenia is complicated by an increased susceptibility to encapsulated germ infections, but an increased risk of thrombosis and pulmonary hypertension has also been reported after surgical splenectomy. Homozygous sickle cell disease is the most common disease associated with functional asplenia. The latter appears early in childhood likely through repeated ischemic alterations caused by the sickling of red blood cells. In addition, specific complications such as hypersplenism and acute splenic sequestration can occur and may be life-threatening. We provide here an update on the role and physiology of the spleen, which will allow a better understanding of the pathophysiology of spleen damage and its consequences in sickle cell disease.

Pneumococcal meningitis as an overwhelming post-splenectomy infection (OPSI) has a higher risk of neurological complications and is sometimes life-threatening. In acute pneumococcal meningitis, four days of dexamethasone is widely used for the prevention of neurological complications. Herein, we report a 68-year-old woman with the diagnosis of pneumococcal meningitis as OPSI. With adequate antibiotics and dexamethasone, her symptoms gradually improved. However, after dexamethasone withdrawal, her consciousness got worse and got into a coma. Brain magnetic resonance imaging revealed acute cerebral infarctions in the bilateral middle cerebral artery territory with multiple vascular stenoses and hydrocephalus. Vascular stenoses improved by follow-up, suggesting cerebral vasospasm. There were no suggestive findings of cerebral vasculitis. Follow-up cerebrospinal fluid analysis showed remained pleocytosis with no bacteria, which could not suggest meningitis recurrence. Since steroid therapy was rapidly withdrawn, we diagnosed that the cerebral vasospasm was due to the steroid rebound phenomenon. The steroid rebound phenomenon due to the excessive immune response to bacterial microstructures has been reported in pneumococcal meningitis. Especially, the present case was asplenia and the usual dexamethasone use would not adequately suppress the immune response to bacterial microstructures. Since pneumococcal meningitis as OPSI has a higher risk of neurological complications, clinicians should consider longer and more cautious steroid tapering.

Asplenia means the absence of a spleen. Asplenia can occur in a variety of clinical settings, and it can refer to an anatomic absence of the spleen or functional asplenia secondary to a variety of disease states. The spleen is one of the primary extramedullary lymphoid organs. It is located in the left upper quadrant of the abdomen. Normally, the spleen is not palpable on physical exam and measures on average 10.65 by 5.16 cm. Normal spleen size can vary by gender and race. For example, men on average have larger spleens than females, and whites, on average, tend to have larger spleens compared to African American individuals.[1] When palpable or notably enlarged on imaging, the clinician must consider a variety of underlying disease states (whether acquired or inherited) contributing to the enlargement. Functionally, the spleen’s primary physiologic role is the filtration and processing of senescent blood cells (predominantly red blood cells or RBCs) and immunologically helps protect against encapsulated microorganisms and respond to infectious pathogens. It contains both hematopoietic and lymphopoietic elements, providing a basis for extramedullary hematopoiesis when necessary.[2] The spleen has two functionally and histologically distinct tissues where these processes take place: the white pulp and the red pulp. The white pulp has a large mass of lymphoid tissue that produces antibodies against recognized antigens, whereas the red pulp has a tight network of sinusoids called the cord of Billroth which helps in blood filtration.[3] As the body's largest filter of blood, it helps to remove old RBCs from the circulation aiding in the removal of blood-borne microorganisms.[4] Beyond the spleen, the lymphatic system of the body consists of a complex myriad of lymphatic vessels, lymph nodes, and other specific extramedullary lymphoid organs including the thymus, tonsils, and appendix, which collectively play a very important role in immune defenses. Asplenia can be caused by damage to the white pulp, the red pulp, or both. The spleen is a direct and indirect site of potential toxicity that can secondarily arise from underlying disease processes or infection.[2] One must understand and appreciate the various etiologies and potential complications of asplenia, such as being a great risk factor for encapsulated microorganisms. Bacterial infections with Neisseria meningitides or Streptococcal pneumoniae, among many others, can become life-threatening if untreated in patients with anatomic or functional asplenia.[5] Patients without a spleen have a 200-fold greater risk of death from septicemia compared to those with an adequate functioning spleen. There are many case reports in the medical literature reporting of asplenic patients, unfortunately, succumbing to infectious disease leading to death. One notable example reported by Heubner ML et al. (2015) described the rare case of a patient who had required splenectomy due to refractory immune thrombocytopenia (ITP).[6] He subsequently developed a pneumococcal meningitis infection and died despite best supportive efforts.  The rate of invasive bacterial infection and mortality in asplenic patients is significantly higher compared to normal controls – 69% in meningitis, 64% in septicemia, and 7% in Purpura fulminans.[5]

Asplenia (the congenital or acquired absence of the spleen) and hyposplenism (defective spleen function) are common causes of morbidity and mortality. The spleen is a secondary lymphoid organ that is responsible for the regulation of immune responses and blood filtration. Hence, asplenia or hyposplenism increases susceptibility to severe and invasive infections, especially those sustained by encapsulated bacteria (namely, Neisseria meningitidis, Streptococcus pneumoniae, Haemophilus influenzae type b). Asplenia is predominantly due to splenectomy for either traumatic events or oncohaematological conditions. Hyposplenism can be caused by several conditions, including haematological, infectious, autoimmune and gastrointestinal disorders. Anatomical disruption of the spleen and depletion of immune cells, especially IgM memory B cells, seem to be predominantly responsible for the clinical manifestations. Early recognition of hyposplenism and proper management of asplenia are warranted to prevent overwhelming post-splenectomy infections through vaccination and antibiotic prophylaxis. Although recommendations are available, the implementation of vaccination strategies, including more effective and immunogenic vaccines, is needed. Additionally, screening programmes for early detection of hyposplenism in high-risk patients and improvement of patient education are warranted.

Introduction. The Ministry of Health has established specific vaccines for people at high risk for invasive infections with encapsulated bacteria (EB). There is currently no information about compliance with the vaccination schedule. Our objective was to assess EB vaccination status in subjects ≤ 18 years with risk factors. Population and methods. Observational, analytical study with a survey to parents of subjects aged ≤ 18 years with HIV, asplenia and/or complement deficiency attending a vaccination center at a children's hospital between October 2020 and September 2021. Sociodemographic and clinical data were collected. Their vaccination status for the EB pneumococcus, meningococcus, and Haemophilus influenzae type b (Hib), their regular vaccination and flu vaccination schedules were assessed. The vaccine hesitancy scale (VHS) was administered: range 10-50. The association between the study variables and EB vaccination was analyzed using logistic regression (OR, 95% CI). The REDCap® database and the STATA ® v.14 software were used. Results. A total of 104 subjects participated; mean age: 9.9 years (SD: 4.4). Asplenia: 91.3%, HIV: 7.6%, and complement deficiency: 0.9%. Socioeconomic level: relative poverty: 38.4%, followed by middle class: 37.5%. Complete vaccination status: meningococcal vaccine 45%, pneumococcal vaccine: 42%, Hib: 97%. The regular vaccination and flu vaccination schedules were up-to-date in 77.9% and 61.5% of cases, respectively. Mean VHS score: 41.9 (SD: 3.2). No significant associations were observed between variables and EB vaccination status. Conclusions. A high percentage of subjects had not completed neither their EB vaccination nor their regular or their flu vaccination schedules. Caregivers' confidence in vaccines was high.

Platelets are a component of blood produced in the bone marrow that plays a vital role in the blood clotting process. The normal platelet count in adults and children is 150,000/microL to 450,000/microL (150 to 450 x 10/L), but the normal range may vary in different clinical laboratories. Thrombocytosis is a condition where the platelet count exceeds 450,000/μl.[1] It is also referred to as thrombocythemia. Thrombocytosis can be divided into two groups:  primary thrombocytosis and secondary (or reactive) thrombocytosis.[2]  This distinction between primary and secondary thrombocytosis is important as it carries implications for evaluation, prognosis, and treatment. Primary thrombocytosis is due to the unregulated abnormality of platelet production of bone marrow progenitor cells.[3] They are usually associated with the myeloproliferative neoplasms group. Primary thrombocytosis, especially essential thrombocythemia and polycythemia vera, have an increased risk of thrombosis and bleeding compared to secondary thrombocytosis.[4] Secondary thrombocytosis, also known as reactive thrombocytosis defined as an abnormally high platelet count due to underlying events, disease, or the use of certain medications. Secondary thrombocytosis is the more common type and is usually identified in routine laboratory results. Among individuals with thrombocytosis, 80% to 90% are known to have secondary thrombocytosis.[5] Reactive causes of thrombocytosis include transient processes such as acute blood loss, acute infection, or sustained forms of reactive thrombocytosis include iron deficiency, asplenia, cancer, chronic inflammatory, or infectious diseases. Secondary thrombocytosis (reactive thrombocytosis) is a laboratory anomaly that resolves when the underlying causative condition is addressed. In most cases, the symptoms are due to an underlying disorder and not the thrombocytosis itself. Extreme thrombocytosis may rarely result in thrombotic events such as acute myocardial infarction, mesenteric vein thrombosis, and pulmonary embolism.[6] Even though secondary thrombocytosis is benign, the underlying etiology of thrombocytosis (e.g., malignancy, connective tissue disorders, chronic infections) can be associated with an increased risk of adverse outcomes.

Human babesiosis is an emerging infectious disease with a progressively rising number of cases in the Northeast over the last few decades. We report a case of fatal babesiosis in a 48-year-old male without significant risk factors for a severe presentation. Clinicians should be aware that even in patients without the classic risk factors of asplenia, advanced age, and immunocompromised status for severe presentations of babesiosis, a deadly case can present. There is a need for further research regarding optimal treatment options for severe babesiosis considering the questionable efficacy of red blood cell exchange (RCE) transfusion in patients who do not improve on the current first-line antimicrobials.

BACKGROUND Babesia species are intraerythrocytic parasitic protozoa that are endemic to the Northeast and north Midwest of the United States. Babesia microti is the most common cause of babesiosis in North America and causes a malaria-like tick-borne parasitosis. Babesia is commonly transmitted through the bite of Ixodes species ticks, often concomitantly with other tick-borne organisms such as Borrelia burgdorferi, Ehrlichia, Rickettsia rickettsii, and Anaplasma phagocytophilum. In the Midwest, Lyme disease is the most common tick-borne illness, and other organisms can sometimes be overlooked. The risk of tick-borne parasitic or bacterial infection is increased in patients after splenectomy. CASE REPORT An 89-year-old man with asplenia and multiple other comorbidities presented to the Emergency Department after a fall at home preceded by 2 to 3 days of fever and loss of appetite and 1 week of generalized weakness. The patient had thrombocytopenia, leukocytosis with neutrophilia, transaminitis, hyperbilirubinemia, and elevated creatine kinase level consistent with tick-borne illness. Laboratory testing revealed Borrelia and Babesia co-infection and other culprits were ruled out via high sensitivity PCR. Owing to the patient's asplenic status, the babesiosis was slow to resolve with appropriate treatment. After an extended 8-week treatment with azithromycin and atovaquone, the patient demonstrated clinical resolution of babesiosis with a negative blood smear. CONCLUSIONS First-line treatment with azithromycin and atovaquone is effective in treating babesiosis even in complicated patients, such as this elderly, asplenic patient. However, in cases such as this, an extended course of a first-line treatment regimen is still appropriate.

Invasive pneumococcal disease occurs in high-risk patient population which includes patients with asplenia and primary hypocomplementaemia. Pneumococcal sepsis can rarely cause disseminated intravascular coagulation (DIC) and intravascular thrombosis of small and medium sized vessels called purpura fulminans which is associated with a high mortality rate. We present the case of an immunocompetent woman in her 50s with an intact spleen who presented with septic shock from Streptococcus pneumoniae bacteraemia. Her hospital course rapidly progressed to multiorgan dysfunction, DIC and purpura fulminans. She was treated aggressively with broad spectrum antibiotics, coagulation factor replacement, multiple vasopressor support, renal replacement therapy and mechanical ventilator support. Despite aggressive measures, she succumbed to the multiorgan failure.

Congenital asplenia is a rare disorder commonly associated with other visceral and cardiac congenital anomalies. Isolated congenital asplenia is even less common than syndromic forms. The risk of severe bacterial infections associated with asplenia is the most concerning clinical implication and carries a significant mortality risk. Prophylactic measures against the clinical syndrome known as overwhelming postsplenectomy infections (OPSI) include vaccination, prophylactic and emergency antibiotics and health education including fever management and travel advice. This case series describes fourteen adults with congenital asplenia and polysplenia syndrome, most of whom were diagnosed incidentally as adults, and outlines the nature of their diagnosis, clinical phenotype, family history and key pathology findings.

Neisseria meningitidis is an aerobic, gram-negative, diplococcus bacterium that is a leading cause of meningitis and sepsis in the United States. Particularly at-risk groups include those with complement deficiencies, people using complement inhibitors, individuals with anatomic or functional asplenia, patients with HIV infection and travelers to endemic countries. There are currently three quadrivalent meningococcal vaccines (Serogroups A, C, W, Y) and two recombinant serogroup B vaccines available for use in the United States, and recommendations for vaccine use have changed rapidly in the past 10-15 years. This article summarizes updated ACIP recommendations for meningococcal vaccination for the primary care provider.

We evaluated compliance to the ACIP pneumococcal vaccination recommendations issued in 2014 for adults aged ≥ 65 years and in 2012 for adults with high-risk (HR) conditions. The MarketScan® Commercial and Medicare Supplemental databases (January 2007-June 2019) were used to identify the cohorts of interest. Analyses for adults aged ≥ 65 years were adjusted to account for missing vaccination history. Two HR cohorts were identified. The HR1 cohort included patients with immunocompromising conditions, functional or anatomic asplenia, cerebrospinal fluid leak, or cochlear implant. The HR2 cohort included patients with chronic heart, lung, or liver disease; diabetes mellitus; alcoholism; cirrhosis; or cigarette smoking. Full compliance for those aged ≥ 65 years or in the HR1 cohort was defined as receipt of PCV13 and PPSV23, and partial compliance was defined as receipt of PCV13 or PPSV23. For those in the HR2 cohort, full compliance was defined as receipt of PPSV23. Annual compliance rates were estimated using the Kaplan-Meier method. Among those aged ≥ 65 years, partial compliance at 4 years post index was 53% and full compliance was 17% in adjusted analyses. In subjects ≥ 65 years receiving the first vaccination, 42% received the second vaccination by year 4. For the HR1 cohort, partial compliance was 19% and full compliance was 5% at 6 years post index date. For the HR2 cohort, full compliance was 20% at 6 years, with the highest rate in patients with diabetes (27%) and the lowest rate in patients with alcoholism (8%). Additional efforts are needed to maximize compliance to the ACIP pneumococcal vaccine recommendations among adults ≥ 65 years of age and adults with HR conditions including streamlined recommendations and single-dose vaccines. These efforts may subsequently reduce the incidence and burden of pneumococcal disease.

Background. Capnocytophaga canimorsus is a fastidious, slow-growing, Gram-negative rod that is a commensal bacterium in normal gingival flora of canine and feline species. Infection with the organism may cause disease ranging from flu-like symptoms to disseminated intravascular coagulation (DIC), fulminant sepsis, meningitis, and endocarditis with an overall fatality rate of 6-26%. Risk factors for infection from C. canimorsus include immunosuppression, alcoholism, and asplenia. Case Presentation. We describe an unusual case with a relatively indolent clinical course and an urticarial exanthem in an otherwise young immunocompetent patient with a history of type 1 diabetes. The patient presented to the Emergency Department (ED) with a <1-day history of rhinorrhea, fever, and dyspnea. He met sepsis criteria on initial presentation, but left against medical advice and returned to the ED the following day, with new arthralgias and a diffuse rash, multiple erythematous, tender macules scattered across his trunk and extremities, and tonsillar erythema. He had not taken the doses of the prescribed amoxicillin. Blood cultures two days later signaled positive for growth with the Gram stain showing a Gram-negative rod. Three 7-8 cm tender targetoid lesions with central clearing were identified on the patient's back. The patient reported two nonengorged ticks crawling on his body a week prior and sustaining a dog bite to his ear three weeks before presentation. Ultimately, the organism was identified as C. canimorsus through MALDI-TOF mass spectrometry and additional biochemical testing. He was given appropriate antibiotics and improved clinically thereafter. Despite the patient's bacteremia, he never progressed to fulminant sepsis and followed a mild clinical course with several unusual characteristics. C. canimorsus is an uncommon cause of illness in humans, but is an important pathogen to consider when evaluating a patient with a dog bite, known risk factors, and an urticarial exanthem as empiric treatment may prevent severe outcomes.

Odontogenic bacteremia, most commonly involving gram-positive oral flora, can result from daily self-care practices or professional dental procedures. Though usually transient and quickly cleared by the immune system, the presence of periodontal disease increases the frequency of exposure and risk of persistence of oral-systemic infections. Comorbidities such as asplenia, alcoholism, and immunocompromise increase the risk of complications of hematogenous spread and severe systemic illness. Capnocytophaga is a genus of anaerobic fastidious gram-negative bacilli, which is a common member of human oral flora, and its density is proportional to mass of dental plaques and periodontal diseases. Capnocytophaga spp that colonize humans are less virulent and are uncommon causes of bacteremia when compared with the Capnocytophaga typical of canines. C gingivalis has been rarely reported as a cause of disease in immunocompromised or immunocompetent hosts. In this article, we present a case of an immunocompromised 70-year-old man with poor oral hygiene, on methotrexate and prednisone for rheumatoid arthritis and sarcoidosis, who was admitted for chronic obstructive pulmonary disease exacerbation and developed C gingivalis bacteremia and septic shock after an episode of upper gastrointestinal bleeding. Poor oral hygiene in our patient is believed to have increased his risk as an immunocompromised patient to developing C gingivalis bacteremia. This case highlights the importance of oral care in immunocompromised patients especially while hospitalized, and those about to receive transplant, chemotherapy, or on immune modulators.

Sickle cell disease (SCD) is associated with vaso-occlusive episodes that affect different organs. Pulmonary involvement is a major cause of morbidity and mortality in this patient population. We performed a literature search in the PubMed database for articles addressing SCD and pulmonary diseases. Acute chest syndrome is defined as a new radiodensity on chest radiograph imaging with a history consistent of the disease. Management includes broad spectrum antibiotics, pain control, and blood transfusions. Microvasculature infarcts lead to functional asplenia, which in turn increases the risk of being infected with encapsulated organisms. Universal vaccinations and antibiotic prophylaxis play a significant role in decreasing mortality from pulmonary infections. Venous thromboembolism in patients with SCD should be treated in the same manner as in the general population. Pulmonary hypertension in patients with SCD also increases mortality. The American Thoracic Society treatment modalities are based on the underlying etiology which is either directed at treating SCD itself, using vasodilator medications if the patient is in group 1, or using long-term anticoagulation if the patient is group 4 (in terms of etiology). Patients with SCD are more likely to suffer from asthma in comparison to controls. Sleep disorders of breathing should be considered in patients with unexplained nocturnal and daytime hypoxemia, or recurrentvaso-occlusive events. Lastly, the utility of pulmonary function tests still needs to be established.

Shingles vaccination and pneumococcal vaccination of patients with celiac disease are among the most recent updates for the vaccination of vulnerable adults, in Switzerland. Shingles and especially post-herpes zoster pain remain an unresolved public health issue. The only vaccine available in Switzerland is very little administered because it is not reimbursed by health insurance companies. A second shingles vaccine is announced for 2022 and should help to reduce the burden of this disease. It has been known for many years that celiac disease is accompanied by hyposplenism in adults. The resulting increased risk of invasive pneumococcal infections justifies, since 2020, a recommendation for vaccination against these encapsulated bacteria.

The primary objective is to evaluate the efficacy of an inactivated and aluminium hydroxide adsorbed SARS-CoV-2 vaccine (Sinovac, China) in voluntary participants after 14 days of the second dose against RT-PCR confirmed symptomatic COVID-19 cases. The secondary objectives include evaluating the efficacy after at least one dose of the vaccine against RT-PCR confirmed symptomatic COVID-19 cases; the efficacy of two doses of the vaccine on the rates of hospitalization and death; the safety of the vaccine including adverse reactions up to one year after the 2nd dose of vaccination; and the immunogenicity of the vaccine and its duration up to 120 days.

Vaccine-preventable diseases and their related complications are associated with increased morbidity and mortality in patients with altered immunocompetence. Optimised immunisation in this patient population is challenging because of limited data from vaccine trials, suboptimal vaccine efficacy and safety concerns. Reliable efficacy data are lacking among patients with altered immunocompetence, and existing recommendations are mainly based on expert consensus and may vary geographically. Inactivated vaccines can be generally used without risks in this group, but their efficacy may be reduced, and immunisation schedules vary according to local guidelines, age, and type and stage of the underlying disease. Live vaccines, if indicated, should be administered with care because of the risk of vaccine-associated disease. We have reviewed the current evidence on vaccination principles and recommendations in adult patients with secondary immunodeficiencies, including asplenia, HIV infection, stem cell and solid organ transplant, haematological malignancies, inflammatory bowel disease and other chronic disorders.

Sickle cell disease (SCD) is one of the most common autosomal recessive disorders in the world. Due to functional asplenia, a dysfunctional antibody response, antibiotic drug resistance and poor response to immunization, SCD patients have impaired immunity. A leading cause of hospitalization and death in SCD patients is the acute chest syndrome (ACS). This complication is especially manifested upon infection of SCD patients with Streptococcus pneumoniae (Spn)-a facultative anaerobic Gram-positive bacterium that causes lower respiratory tract infections. Spn has developed increased rates of antibiotics resistance and is particularly virulent in SCD patients. The primary defense against Spn is the generation of reactive oxygen species (ROS) during the oxidative burst of neutrophils and macrophages. Paradoxically, Spn itself produces high levels of the ROS hydrogen peroxide (H2O2) as a virulence strategy. Apart from H2O2, Spn also secretes another virulence factor, i.e., the pore-forming exotoxin pneumolysin (PLY), a potent mediator of lung injury in patients with pneumonia in general and particularly in those with SCD. PLY is released early on in infection either by autolysis or bacterial lysis following the treatment with antibiotics and has a broad range of biological activities. This review will discuss recent findings on the role of pneumococci in ACS pathogenesis and on strategies to counteract the devastating effects of its virulence factors on the lungs in SCD patients.

Vaccination of at-risk populations against Neisseria meningitidis is an important strategy to prevent invasive meningococcal disease (IMD). The objective of this study was to characterize preexisting risk factors in patients with IMD and to compare their relative importance. This case-control analysis was performed in the French national public health insurance database (SNDS). Cases consisted of all people hospitalized for IMD in France over a six-year period (2012-2017). Controls were matched by age, gender, and district of residence. Medical risk factors were identified from ICD-10 codes in the SNDS. Socioeconomic risk factors studied were low household income and social deprivation of the municipality of residence. Associations of these risk factors with hospitalization for IMD were quantified as odds ratios (ORs) between cases and controls with their 95% confidence intervals (95%CI). The medical risk factors showing the most robust associations were congenital immunodeficiency (OR: 39.1 [95%CI: 5.1-299], acquired immunodeficiency (10.3 [4.5-24.0]) and asplenia/hyposplenia (6.7 [3.7-14.7]). In addition, certain chronic medical conditions, such as autoimmune disorders (5.4 [2.5-11.8]), hemophilia (4.7 [1.8-12.2]) and severe chronic respiratory disorders (4.3 [3.1-6.2]) were also strongly associated, as was low household income (1.68 [1.49-1.80]). In conclusion, this study has documented potential risk factors associated with hospitalization for IMD in a large and comprehensive sample of individuals with IMD in France. Several of the risk factors identified may help identify groups who could benefit from targeted prevention measures (such as vaccination) in order to reduce the burden of IMD.

This report compiles and summarizes all recommendations from CDC's Advisory Committee on Immunization Practices (ACIP) for use of meningococcal vaccines in the United States. As a comprehensive summary and update of previously published recommendations, it replaces all previously published reports and policy notes. This report also contains new recommendations for administration of booster doses of serogroup B meningococcal (MenB) vaccine for persons at increased risk for serogroup B meningococcal disease. These guidelines will be updated as needed on the basis of availability of new data or licensure of new meningococcal vaccines. ACIP recommends routine vaccination with a quadrivalent meningococcal conjugate vaccine (MenACWY) for adolescents aged 11 or 12 years, with a booster dose at age 16 years. ACIP also recommends routine vaccination with MenACWY for persons aged ≥2 months at increased risk for meningococcal disease caused by serogroups A, C, W, or Y, including persons who have persistent complement component deficiencies; persons receiving a complement inhibitor (e.g., eculizumab [Soliris] or ravulizumab [Ultomiris]); persons who have anatomic or functional asplenia; persons with human immunodeficiency virus infection; microbiologists routinely exposed to isolates of Neisseria meningitidis; persons identified to be at increased risk because of a meningococcal disease outbreak caused by serogroups A, C, W, or Y; persons who travel to or live in areas in which meningococcal disease is hyperendemic or epidemic; unvaccinated or incompletely vaccinated first-year college students living in residence halls; and military recruits. ACIP recommends MenACWY booster doses for previously vaccinated persons who become or remain at increased risk.In addition, ACIP recommends routine use of MenB vaccine series among persons aged ≥10 years who are at increased risk for serogroup B meningococcal disease, including persons who have persistent complement component deficiencies; persons receiving a complement inhibitor; persons who have anatomic or functional asplenia; microbiologists who are routinely exposed to isolates of N. meningitidis; and persons identified to be at increased risk because of a meningococcal disease outbreak caused by serogroup B. ACIP recommends MenB booster doses for previously vaccinated persons who become or remain at increased risk. In addition, ACIP recommends a MenB series for adolescents and young adults aged 16-23 years on the basis of shared clinical decision-making to provide short-term protection against disease caused by most strains of serogroup B N. meningitidis.