Pneumococcal vaccination in autoimmune rheumatic diseases

Antibody responses after sequential vaccination with PCV13 and PPSV23 in patients with moderate to severe plaque psoriasis under immunosuppressive therapy

A crucial step in lowering the risk of invasive pneumococcal illness in high-risk populations, such as individuals with plaque psoriasis, is pneumococcal vaccination. The serologic response to the sequential vaccination with Prevenar 13 (PCV13) and Pneumovax 23 (PPSV23) in psoriasis patients under immunosuppressive therapy is still poorly characterized despite national recommendations suggesting vaccination for immunocompromised patients. In this prospective study, we investigated the serological response in 57 patients under active systemic treatment for moderate to severe plaque psoriasis who underwent sequential vaccination with PCV13 followed by PPSV23. Our analysis focused on global and serotype-specific anti-pneumococcal antibody responses over a 7-month period post-vaccination. Our findings reveal a robust serological response in patients with plaque psoriasis under systemic therapy. When comparing our results with a cohort of kidney transplant recipients who completed a similar sequential vaccination protocol, psoriasis patients showed higher antibody concentrations. In psoriasis patients, the mean levels of all global antibody classes tested (IgG, IgG2, IgA, IgM) increased more than 4-fold (P < 0.0001) and serotype-specific antibodies more than 1.9-fold (P < 0.01). In addition to providing strong evidence of the safety and effectiveness of sequential pneumococcal vaccination in individuals with plaque psoriasis, our work sheds light on the complex interactions that exist between immunosuppressive treatment, vaccination schedule, and antibody responses in various risk groups.

IMPORTANCE

To protect against severe courses of infection with Streptococcus pneumoniae, the national guidelines recommend sequential vaccination for these patients. However, there are only studies on the efficacy of a single administration of these vaccines in this particular risk group. The immunological responses to the vaccine were correlated with clinical patient data. In summary, our study shows for the first time that sequential vaccination is immunogenic in patients with moderate to severe plaque psoriasis.

Vaccination strategies for patients under monoclonal antibody and other biological treatments: an updated comprehensive review based on EMA authorisations to January 2024

INTRODUCTION

Monoclonal antibodies (mAbs) and other biological agents are being increasingly approved in the last years with very different indications. Their highly heterogeneous immunosuppressive effects, mechanisms of action and pharmacokinetics require comprehensive individualized vaccination schedules.

AREAS COVERED

Vaccination for immunocompromised patients. Prevention and treatment with mAbs and other biological therapies.

EXPERT OPINION

Current recommendations on vaccine schedules for patients under mAbs or other biological treatments are based on expert opinions and are not individualized according to each vaccine and treatment. No studies are focusing on the high heterogeneity of these agents, which are exponentially developed and used for many different indications. Recent paradigm changes in vaccine development (boosted by the COVID-19 pandemic) and in the mAbs use for prophylactic purposes (changing 'vaccination' by 'immunization' schedules) has been witnessed in the last years. We aimed at collecting all mAbs used for treatment or prevention, approved as of 1 January 2024, by the EMA. Based on available data on mAbs and vaccines, we propose a comprehensive guide for personalizing vaccination. Recent vaccine developments and current population strategies (e.g. zoster vaccination or prophylactic nirsevimab) are discussed. This review aims to be a practical guideline for professionals working in vaccine consultations for immunosuppressed patients.

Invasive Pneumococcal Diseases in Korean Adults After the Introduction of Pneumococcal Vaccine into the National Immunization Program

Although Streptococcus pneumoniae has been one of the most common bacterial causes of disease in humans, its impact has been blunted by the broad use of vaccines. Since 2018, the incidence of invasive pneumococcal disease in Korea decreased with effective pneumococcal vaccines but is on the rise again recently. In this paper I will review the epidemiology, risk factors, and antibiotic resistance of invasive pneumococcal disease after the introduction of the pneumococcal vaccine in Korean adults.

Preventing infections in immunocompromised patients with kidney diseases: vaccines and antimicrobial prophylaxis

The coronavirus disease 2019 (COVID-19) pandemic revealed that our understanding of infectious complications and strategies to mitigate severe infections in patients with glomerular diseases is limited. Beyond COVID-19, there are several infections that specifically impact care of patients receiving immunosuppressive measures. This review will provide an overview of six different infectious complications frequently encountered in patients with glomerular diseases, and will focus on recent achievements in terms of vaccine developments and understanding of the use of specific antimicrobial prophylaxis. These include influenza virus, Streptococcus pneumoniae, reactivation of a chronic or past infection with hepatitis B virus in cases receiving B-cell depletion, reactivation of cytomegalovirus, and cases of Pneumocystis jirovecii pneumonia in patients with anti-neutrophil cytoplasmic antibody-associated vasculitis. Varicella zoster virus infections are particularly frequent in patients with systemic lupus erythematosus and an inactivated vaccine is available to use as an alternative to the attenuated vaccine in patients receiving immunosuppressants. As with COVID-19 vaccines, vaccine responses are generally impaired in older patients, and after recent administration of B-cell depleting agents, and high doses of mycophenolate mofetil and other immunosuppressants. Strategies to curb infectious complications are manifold and will be outlined in this review.

Risk of Pneumococcal Disease in US Adults by Age and Risk Profile

Background

Older age and certain medical conditions are known to modify the risk of pneumococcal disease among adults. We quantified the risk of pneumococcal disease among adults with and without medical conditions in the United States between 2016 and 2019.

Methods

This retrospective cohort study used administrative health claims data from Optum's de-identified Clinformatics Data Mart Database. Incidence rates of pneumococcal disease-all-cause pneumonia, invasive pneumococcal disease (IPD), and pneumococcal pneumonia-were estimated by age group, risk profile (healthy, chronic, other, and immunocompromising medical condition), and individual medical condition. Rate ratios and 95% CIs were calculated comparing adults with risk conditions with age-stratified healthy counterparts.

Results

Among adults aged 18-49 years, 50-64 years, and ≥65 years, the rates of all-cause pneumonia per 100 000 patient-years were 953, 2679, and 6930, respectively. For the 3 age groups, the rate ratios of adults with any chronic medical condition vs healthy counterparts were 2.9 (95% CI, 2.8-2.9), 3.3 (95% CI, 3.2-3.3), and 3.2 (95% CI, 3.2-3.2), while the rate ratios of adults with any immunocompromising condition vs healthy counterparts were 4.2 (95% CI, 4.1-4.3), 5.8 (95% CI, 5.7-5.9), and 5.3 (95% CI, 5.3-5.4). Similar trends were observed for IPD and pneumococcal pneumonia. Persons with other medical conditions, such as obesity, obstructive sleep apnea, and neurologic disorders, were associated with increased risk of pneumococcal disease.

Conclusions

The risk of pneumococcal disease was high among older adults and adults with certain risk conditions, particularly immunocompromising conditions.

A comprehensive overview of pneumococcal vaccination recommendations for adults in South Africa, 2022

Pneumococcal infections remain a common global cause of significant morbidity and mortality. The first recommendations for adult pneumococcal vaccination, published in South Africa in 1999, contained information only on the 23-valent polysaccharide vaccine (PPV23). With the introduction of the 13-valent pneumococcal conjugate vaccine (PCV13) for use in adults and the perceived uncertainty that most clinicians had regarding use of these vaccines in adults, these vaccine recommendations were updated in 2022. A Working Group, which consisted of individuals in various fields of medical practice in South Africa, who were from different areas of the country, and included clinicians from both the public and private sectors, was assembled to revise the recommendations. The expertise of the participants varied widely, dependent on their training and specialty, and encompassed different organ systems, disease conditions, and/or practice types. Each participant was allocated a different section, based on their expertise, for which they were required to do an extensive review of the current literature and write their section. The entire working group then reviewed the complete document several times, following additional comments and recommendations. This update contains recommendations for the use of both PPV23 and PCV13, either alone, or in sequence, both in vaccine naïve and in previously vaccinated individuals. It includes both age and risk categories, and encompasses the elderly (≥65 years), as well as younger adults (<65 years) with comorbid conditions or with high-risk conditions and/or immunocompromise. It is hoped that this review and its associated vaccine recommendations will clarify for clinicians, from all spheres of practice in South Africa, how, where, and when pneumococcal vaccines should be used in adults, with the ultimate goal of significantly increasing the appropriate use of these vaccines, in order to decrease the substantial morbidity and mortality associated with pneumococcal infections in adults in South Africa. Furthermore, it is hoped that this review of local epidemiological data and the manner in which this information was interpreted in the development of these local vaccine recommendations, could be used as an example for other regions of the world, to tailor their recommendations to locally available epidemiological data.

Vaccinations in Patients with Rheumatic Disease: Consider Disease and Therapy

Patients with rheumatic diseases are susceptible to infections due to their underlying disease states as well as from immunosuppressive medications, highlighting the importance of vaccination, these same factors also pose challenges to vaccine efficacy, safety, and uptake. This article reviews the impact of immunosuppressive therapies and rheumatic disease on vaccine efficacy in this vulnerable patient population as well as discusses best practices.

Vaccination coverage in hematological patients undergoing chemotherapy: Should we move towards personalized vaccination?

INTRODUCTION

Immunocompromised patients are at high-risk for severe influenza and invasive pneumococcal diseases (IPD). Despite the French Public Health Council (FPHC) and the 7th European Conference on Infections in Leukaemia (ECIL7) recommendations, vaccination coverage remains insufficient. This study aimed to estimate the coverage and determinants of influenza, pneumococcal and diphtheria-tetanus-poliomyelitis (dTP) vaccinations in hematological patients underlying chemotherapy.

METHODS

A survey was distributed to all patients of the hematology day hospital assessing vaccine uptakes and general opinion about vaccination. Vaccine uptakes were collected from medical and vaccination records; knowledge of and attitudes towards vaccinations in immunocompromised patients were evaluated for each general practitioner (GP) by phone call. Adequacy between vaccine uptakes and indication or not to vaccinate according to ECIL7 guidelines was assessed. Factors associated with vaccine uptakes were assessed by multivariate logistic regression.

RESULTS

Among 145 patients, 66 % were aged 65 years or older, 40 % were followed for lymphoma and 38 % for multiple myeloma, 39 % were treated with anti-CD20 antibodies. Vaccination coverage was suboptimal for influenza (45-56 %), dTP (44 %) and IPD (16-19 %) regardless of the guidelines followed, with a wide variation in rates by information source (19-76 %). Adequacy rate with ECIL7 recommendations were 63 % and 87 % for influenza and IPD respectively. Information of patients on specific vaccinations was positively associated with flu and IPD vaccinations, as well as favorable attitude toward vaccination and age ≥ 65 years for flu vaccination, and recommendation by hematologist for pneumococcal vaccination.

CONCLUSION

Despite vaccination opportunities, the complexity of these specific recommendations and the lack of communication between the health actors could explain the suboptimal vaccination coverage in this high-risk population. A proactive attitude of all actors in the city and hospital, including better patient information and a personalized and evolving vaccination schedule to help GPs to coordinate vaccination would allow to improve vaccine coverage.

To Be or Not To Be Vaccinated: That Is a Question in Myasthenia Gravis

Myasthenia gravis (MG) is an autoimmune disease characterized by muscle weakness and abnormal fatigability due to the antibodies against postsynaptic receptors. Despite the individual discrepancy, patients with MG share common muscle weakness, autoimmune dysfunction, and immunosuppressive treatment, which predispose them to infections that can trigger or exacerbate MG. Vaccination, as a mainstay of prophylaxis, is a major management strategy. However, the past years have seen growth in vaccine hesitancy, owing to safety and efficacy concerns. Ironically, vaccines, serving as an essential and effective means of defense, may induce similar immune cross-reactivity to what they are meant to prevent. Herein, we outline the progress in vaccination, review the current status, and postulate the clinical association among MG, vaccination, and immunosuppression. We also address safety and efficacy concerns of vaccination in MG, in relation to COVID-19. Since only a handful of studies have reported vaccination in individuals with MG, we further review the current clinical studies and guidelines in rheumatic diseases. Overall, our reviews offer a reference to guide future vaccine clinical decision-making and improve the management of MG patients.

Pneumococcal Vaccination in Immunocompromised Hosts: An Update

Infections with the pathogen, Streptococcus pneumoniae, are a common cause of morbidity and mortality worldwide. It particularly affects those at the extremes of age and immunocompromised individuals. Preventing pneumococcal disease is paramount in at risk individuals, and pneumococcal vaccination should be offered. Here, we discuss the role of pneumococcal vaccination in specific groups of immunocompromised hosts.

Vaccinations in Patients with Rheumatic Disease: Consider Disease and Therapy

Patients with rheumatic diseases are susceptible to infections due to their underlying disease states as well as from immunosuppressive medications, highlighting the importance of vaccination, these same factors also pose challenges to vaccine efficacy, safety, and uptake. This article reviews the impact of immunosuppressive therapies and rheumatic disease on vaccine efficacy in this vulnerable patient population as well as discusses best practices.

Vaccination in patients under monoclonal antibody treatment: an updated comprehensive review

INTRODUCTION

Monoclonal antibodies (mAbs) have become an increasing source of biological treatments. Clinicians should make an effort to update their knowledge on mechanisms of action, indications, and adverse events of these novel therapies. Most of them have immunosuppressive effects and, therefore, vaccination is indicated.

AREAS COVERED

vaccination of patients under mAbs therapies.

EXPERT OPINION

Recommendations on vaccination are still based on expert recommendations and have not been updated in recent years. Specific recommendations for each mAb have not been addressed in the current literature. The aim of this comprehensive review was to collect all the therapeutic mAbs approved up to 1 January 2020 and, based on previous recommendations and the pharmaceutical characteristics of each drug, to propose an updated guide with recommendations on vaccination. Influenza, sequential pneumococcal and Hepatitis B vaccination in patients with negative serology were the only consistent recommendations. Hepatitis A vaccination was proposed for mAbs with special hepatotoxic characteristics. Other vaccines are reviewed and discussed. Several non-immunosuppressive mAbs were detected and, therefore, vaccinations not recommended. We hope that this review can serve as a starting point for compiling updated vaccination recommendations and collecting all the therapeutic mAbs approved up to 2020.

Management of central nervous system demyelinating diseases during the coronavirus disease 2019 pandemic: a practical approach

BACKGROUND

The novel coronavirus disease 2019 (COVID-19) pandemic poses a potential threat to patients with autoimmune disorders, including multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD). Such patients are usually treated with immunomodulatory or immunosuppressive agents, which may tamper with the organism's normal response to infections. Currently, no consensus has been reached on how to manage MS and NMOSD patients during the pandemic.

OBJECTIVE

To discuss strategies to manage those patients.

METHODS

We focus on how to 1) reduce COVID-19 infection risk, such as social distancing, telemedicine, and wider interval between laboratory testing/imaging; 2) manage relapses, such as avoiding treatment of mild relapse and using oral steroids; 3) manage disease-modifying therapies, such as preference for drugs associated with lower infection risk (interferons, glatiramer, teriflunomide, and natalizumab) and extended-interval dosing of natalizumab, when safe; 4) individualize the chosen MS induction-therapy (anti-CD20 monoclonal antibodies, alemtuzumab, and cladribine); 5) manage NMOSD preventive therapies, including initial therapy selection and current treatment maintenance; 6) manage MS/NMOSD patients infected with COVID-19.

CONCLUSIONS

In the future, real-world case series of MS/NMOSD patients infected with COVID-19 will help us define the best management strategies. For the time being, we rely on expert experience and guidance.

The Practice Guideline for Vaccinating Korean Patients with Autoimmune Inflammatory Rheumatic Disease

To develop a clinical practice guideline for vaccination in patients with autoimmune inflammatory rheumatic disease (AIIRD), the Korean College of Rheumatology and the Korean Society of Infectious Diseases developed a clinical practice guideline according to the clinical practice guideline development manual. Since vaccination is unlikely to cause AIIRD or worsen disease activities, required vaccinations are recommended. Once patients are diagnosed with AIIRD, treatment strategies should be established and, at the same time, monitor their vaccination history. It is recommended to administer vaccines when the disease enters the stabilized stage. Administering live attenuated vaccines in patients with AIIRD who are taking immunosuppressants should be avoided. Vaccination should be considered in patients with AIIRD, prior to initiating immunosuppressants. It is recommended to administer influenza, Streptococcus pneumoniae, hepatitis A, hepatitis B, herpes zoster, measles-mumps-rubella virus, human papillomavirus, and tetanus-diphtheria-pertussis vaccines in patients with AIIRD; such patients who planned to travel are generally recommended to be vaccinated at the recommended vaccine level of healthy adults. Those who live in a household with patients with AIIRD and their caregivers should also be vaccinated at levels that are generally recommended for healthy adults.

A quality improvement intervention failed to significantly increase pneumococcal and influenza vaccination rates in immunosuppressed inflammatory arthritis patients

OBJECTIVES

Pneumococcal and influenza vaccination rates have been suboptimal in studies of immunosuppressed patients. We aimed to assess barriers to and increase rates of 23-valent pneumococcal polysaccharide vaccine (PPSV23) and influenza vaccination in this group. The primary endpoint was a statistically significant increase in adequate PPSV23 and influenza vaccination.

METHODS

In 2017, rheumatology outpatients completed an anonymous questionnaire recording vaccination knowledge, status, and barriers. Simultaneously, a low-cost multifaceted quality improvement (QI) intervention was performed. All outpatients on oral steroids, immunosuppressant conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) or biologics disease-modifying antirheumatic drugs (bDMARDs) were included in the study. In 2018, post-intervention, the clinic was re-assessed. Demographics, diagnosis, medications, smart phone access, and willingness to use this for vaccination reminders were assessed for independent vaccination predictors using binary logistic regression analysis.

RESULTS

Four hundred twenty-five patients were included (72.6% rheumatoid arthritis, 74% women, 45.6% ≥ 60 years old). From 2017 to 2018, PPSV23 vaccination rates changed from 41.0 to 47.2% (P = 0.29) and influenza from 61.8 to 62.1% (P = 0.95). The most common reason for non-vaccination was lack of awareness. Following the intervention, this changed for influenza (36.7 to 34.2%) and PPSV23 (82.1 to 76.4%). General practitioners performed most vaccinations, only 3.6% were delivered in the hospital. Significant predictors of PPSV23 vaccination were older age {≥ 80 years had an OR 41.66 (95% CI 3.69-469.8, P = 0.003), compared with ≤ 39 years}, bDMARD use (OR 2.80, 95% CI 1.24-6.32, P = 0.013), and adequate influenza vaccination (OR 9.01, 95% CI 4.40-18.42, P < 0.001). Up-to-date PPSV23 vaccination (OR 8.93, 95% CI 4.39-18.17, P < 0.001) predicted influenza vaccination.

CONCLUSIONS

PPSV23 and influenza vaccination rates were suboptimal. The intervention did not cause a statistically significant change in vaccination rates. Point-of-care vaccination may be more effective.Key Points• Low vaccination rates amongst immunosuppressed inflammatory arthritis outpatients• Less than 5% of vaccinations occurred in hospital• There was no statistically significant difference in the rates of adequate PPSV23 (41.0 to 47.2%) or influenza (61.8 to 62.1%) vaccination following our intervention.

Impact of synthetic and biological immunomodulatory therapy on the duration of 17DD yellow fever vaccine-induced immunity in rheumatoid arthritis

Background

The 17DD-yellow fever (YF) vaccine induces a long-lasting protective immunity, resulting from humoral and cellular immunological memory. The treatment of rheumatoid arthritis (RA) patients with disease-modifying anti-rheumatic drugs (DMARD) may affect pre-existing 17DD-vaccine protective immunity and increase the risk of acquiring YF infection. Our goal was to determine whether DMARD would affect the duration of YF-specific protective immunity in RA patients.

Methods

A total of 122 RA patients, previously immunized with the 17DD-YF vaccine (1–5, 5–9, and ≥ 10 years) and currently under DMARD therapy, were enrolled in the present investigation. Immunomodulatory therapy encompasses the use of conventional synthetic DMARD alone (csDMARD) or combines with biological DMARD (cs+bDMARD). A total of 226 healthy subjects were recruited as a control group (CONT). Neutralizing antibody responses were measured by a plaque-reduction neutralization test (PRNT), and cellular immunity was evaluated by an in vitro 17DD-YF-specific peripheral blood lymphoproliferative assay.

Results

The data demonstrated that csDMARD therapy did not affect the duration of protective immunity induced by the 17DD-YF vaccine compared to that of CONT, as both presented a significant time-dependent decline at 10 years after vaccination. Conversely, cs+bDMARD therapy induced a premature depletion in the main determinants of the vaccine protective response, with diminished PRNT seropositivity levels between 5 and 9 years and impaired effector memory in CD8⁺ T cells as early as 1–5 years after 17DD-YF vaccination.

Conclusions

These findings could support changing the vaccination schedule of this population, with the possibility of a planned booster dose upon the suspension of bDMARD in cases where this is allowed, even before 10 years following 17DD-YF vaccination. The benefit of a planned booster dose should be evaluated in further studies.

Trial registration

RBR-946bv5. Date of registration: March 05, 2018. Retrospectively registered

Immunogenicity, safety and tolerability of anti-pneumococcal vaccination in systemic lupus erythematosus patients: An evidence-informed and PRISMA compliant systematic review and meta-analysis

The immunological perturbations associated with systemic lupus erythematosus (SLE) put many patients at a higher risk of infections, including pneumococcal pneumonia. However, the uptake and utility of anti-pneumococcal vaccines in SLE patient is both controversial and not completely agreed upon. Indeed, several epidemiological studies of anti-pneumococcal vaccine safety and efficacy in SLE have reported short-term immunogenicity with elevated anti-pneumococcal antibody titres but inconsistent long-term findings, with some studies finding poor responses, mainly for long-term immune protection. Moreover, the safety and efficacy of the pneumococcal vaccine in SLE patients remains controversial due to the different types of anti-pneumococcal vaccines, and the heterogeneity of SLE patients. Several reviews addressing anti-pneumococcal vaccination in SLE patients exist, however, to the best of our knowledge, the present is the first systematic review and meta-analysis. To better understand the efficacy and safety of pneumococcal vaccination in SLE, a comprehensive literature search was performed identifying 18 studies, which have been included in the present systematic review and meta-analysis. All studies were designed as longitudinal investigations, 2, in particular, were of high quality, being randomized, double-blind trials (RCTs). Four studies had control groups. Total sample size included 601 participants. Vaccine immunogenicity in terms of subjects with protective antibody titers ranged from 36% to 97.6%. According to our systematic review and metanalysis, high erythrocyte sedimentation rate (ESR), older age, earlier SLE onset, high disease activity, and immunosuppressive therapy were predictors of poor immunogenicity, although belimumab was found to have no significant impact. With regard to safety, no serious adverse events were found, with up to one third of cases reporting mild/low-grade complaints. In conclusion, due to the high risk of pneumococcal infection in SLE patients and given the safety and, at least partial, effectiveness, according to our systematic review and meta-analysis, in such patients, preventive strategies mainly by immunization, are required in all age groups and, in those needing immunosuppressive therapy, immunization should be given prior the initiation of the treatment. PROSPERO registration code CRD42018103605.

VACCINATION IN RHEUMATIC DISEASES: AN ALLY OR AN ENEMY?

The importance of comorbid infections in rheumatology has recently increased substantially, particularly due to the introduction of biological agents into clinical practice. One of the ways to solve the above problem is to investigate and actively use different vaccines. The paper deals with the issues concerning the use of vaccines against influenza and pneumococcal infections in rheumatic patients. It discusses the safety and immunogenicity of vaccination in preventing respiratory infections as the most common cause of an adverse outcome in rheumatic diseases. Main areas for future investigations of the considered problem are shown.

 

Anti-polysaccharide and anti-diphtheria protective antibodies after 13-valent pneumococcal conjugate vaccination in rheumatoid arthritis patients under immunosuppressive therapy

Immunogenicity of 13-valent pneumococcal polysaccharide (PnPS) conjugate vaccine (PCV13) was evaluated in 38 rheumatoid arthritis patients under immunosuppressive treatment and 20 healthy controls (HC). Antibodies to all PnPS and diphtheria-toxin analogue conjugate protein were measured pre- (T0), 1 (T1), 6 (T2), 12 (T3) months post-immunization. Patients and HC had similar response to individual PnPS. Mean antibody levels to all PnPS but one doubled at T1 compared with T0, with T3 persistence for only 8-7/13 PnPS. Baseline antibody levels was inversely associated with the rate of responders at T1 (T1/T0≥2) to 11/13 PnPS. Few subjects reached protective IgG levels against some serotypes frequently isolated in Italian patients with invasive pneumococcal disease. Antibody response was not influenced by therapy, except the one to PS7F, which was reduced by tumor necrosis factor-α-inhibitors. Vaccination increased also anti-diphtheria IgG. Despite this study substantially confirmed the PCV13 immunogenicity in immunocompromised patients, it also revealed some limitations.