Pneumococcal Vaccination in Immunocompromised Hosts: An Update

Study of pediatric invasive pneumococcal disease in the 13-pneumococcal conjugated vaccine era

BACKGROUND

Invasive pneumococcal disease (IPD) remains a significant concern among children under 5, despite vaccination efforts. This study assessed IPD prevalence and associated risks in pediatric population.

METHODS

An observational, retrospective, multicenter study in Comunidad Valenciana, Spain, of IPD cases in children under 13 from January 2012 to September 2022. Data from the CV Microbiology Surveillance Network (RedMIVA) and medical records were reviewed.

RESULTS

A total of 379 IPD cases in 377 patients were analyzed, predominantly males (54.11 %) under 5 (81.17 %). PCV13 vaccination notably reduced PCV13-serotypes IPD (p=0.0002), except serotype 3. Pneumonia was common, with half having underlying conditions (50.40 %). Worse outcomes occurred in patients with neurological disorders (ANOVA, p=0.57). Vaccine failures often involved underlying conditions (63 %) and serotypes 3 and 19A. Immunodeficiencies may relate to recurrent IPD, but evidence is limited.

CONCLUSION

Despite vaccination, IPD still impacts children, influenced by immunological status, affecting severity and mortality.

Evaluating immune responses to pneumococcal vaccines

Streptococcus pneumoniae (pneumococcus) is a significant cause of bacterial infections ranging from mild infections affecting the respiratory tract such as otitis media and sinusitis to severe diseases including bacteremia, pneumonia, and invasive pneumococcal disease (IPD) (eg, meningitis, septic arthritis, and endocarditis). Pneumococcal vaccines were first developed in the 1970s as capsular pneumococcal polysaccharide vaccines, which were T-cell independent and hence lacked immunologic memory. Subsequently in the year 2000, pneumococcal conjugate vaccines (PCV) conjugated to a protein to increase immunogenicity were developed and made commercially available. The increasing number of pneumococcal serotypes identified and the expanding pipeline of PCV vaccines with improved immunogenicity have significantly reduced the morbidity and mortality associated with IPD in high-risk patients. Pneumococcal vaccines also play an important role in the diagnosis and immunophenotyping of children and adults with inborn errors of immunity (IEI) given the increasing diversity/heterogeneity of IEI presenting with primary and/or specific antibody deficiency. Other than the quantitation of serotype levels in routine clinical care, other measurements of immune response including the functional activity of antibodies, antibody avidity, cell-mediated immunity, and immunological memory remain limited to clinical trials during vaccine development.

Clinical and laboratory characteristics of patients with symptomatic secondary immunodeficiency following the treatment of haematological malignancies

Secondary immunodeficiency (SID), manifesting as increased susceptibility to infection, is an emergent clinical problem in haematoncology. Management of SID includes vaccination, prophylactic antibiotics (pAbx) and immunoglobulin replacement therapy (IgRT). We report clinical and laboratory parameters of 75 individuals, treated for haematological malignancy, who were referred for immunological assessment due to recurrent infections. Forty-five were managed with pAbx while thirty required IgRT after failing to improve on pAbx. Individuals requiring IgRT had significantly more bacterial, viral and fungal infections resulting in hospitalization at least 5 years after their original haemato-oncological diagnosis. Following immunological assessment and intervention, a 4.39-fold reduction in the frequency of hospital admissions to treat infection was observed in the IgRT cohort and a 2.30-fold reduction in the pAbx cohort. Significant reductions in outpatient antibiotic use were also observed in both cohorts following immunology input. Patients requiring IgRT were more hypogammaglobulinaemic and had lower titres of pathogen-specific antibodies and smaller memory B cell populations than those requiring pAbx. Test vaccination with pneumococcal conjugate vaccine discriminated poorly between the two groups. Patients requiring IgRT could be distinguished by combining wider pathogen-specific serology with a frequency of hospital admissions for infection. If validated in larger cohorts, this approach may circumvent the need for test vaccination and enhance patient selection for IgRT.

IgG antibody response to pneumococcal-conjugated vaccine (Prevenar®13) in children with immunodeficiency disorders

Measurement of anti-pneumococcal capsular polysaccharides (anti-PnPs) IgG titers is an important tool in the immunologic assessment of patients with suspected immunodeficiency disorders (ID) to reduce the morbi-mortality and minimize severe infections. Retrospectively, we studied the relationship among anti-PnPs IgG response to 3 doses of Prevenar®13, levels of immune system components, leukocyte populations, and clinical data in children with ID. Serum samples were collected at least 4 weeks post vaccination. Subsequently, multi-serotype enzyme-linked immunosorbent assay (ELISA) was performed. Eighty-seven children (under 12 years) were enrolled. Primary immunodeficiency disorder (PID) was the most common disorder (45) followed by possible immunodeficiency disorder (POID) (19), secondary immunodeficiency disorder (SID) (15), and mixed immunodeficiency disorder (MID) (8). The median age was 3 (1.50-5.33) years, 65% of patients were male. Deficient production of anti-PnPs IgG (titer ≤ 50 mg/L) was detected in 47 patients (54%), especially in the MID group, all of them under immunosuppressive therapy. In PCV13 responders, the mean of leukocyte population levels was higher with statistically significance differences in CD4 + /CD8 + T lymphocytes (p = 0.372, p = 0.014) and CD56 + /CD16 + NK (p = 0.016). Patients with previous bone marrow transplantation were the worst PCV13 responders. Pneumococcal IgG antibody titers (post-vaccination) along with clinical and analytical markers represented.

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.

A Closer Look at the Role of Anti-CCP Antibodies in the Pathogenesis of Rheumatoid Arthritis-Associated Interstitial Lung Disease and Bronchiectasis

Rheumatoid arthritis (RA) is an articular disease with extra-articular manifestations. Pulmonary manifestations are not uncommon and can involve all compartments of the lungs with airway disease in the form of bronchiectasis or bronchiolitis, interstitial lung disease (ILD), pleural effusions and parenchymal lung nodules. The pulmonary features may present synchronously or after the articular disease, but, importantly, it may be the first presentation in 10% of patients in the absence of articular symptoms. Here we discuss the pathogenesis of RA lung involvement, particularly interstitial lung disease and bronchiectasis, focusing on the role anti-CCP antibodies (ACPAs). We highlight the complex interplay among genetic, environmental and immune factors. Furthermore, we explore the relationship of citrullination and smoking as well as the concept of interstitial pneumonia with autoimmune features (IPAF), where patients do not have evidence of another known cause of interstitial pneumonia and have incomplete features of connective tissue disease (CTD). We surmise that the frequency and titers of rheumatoid factor (RF) and ACPAs are increased in bronchiectasis and RA-bronchiectasis compared to RA patients without lung disease. ACPA is associated with more severe disease in both RA-ILD and RA-bronchiectasis even in the absence of articular symptoms. There is no clear prediction of development of articular RA with high ACPA levels in the context of positive ACPA and ILD; however, in RA-bronchiectasis, patients with positive antibodies can develop RA within a year after diagnosis of bronchiectasis. Though the primary focus of this narrative is to highlight the role of ACPA in pathogenesis and clinical practice, we also discuss the current treatment options and trials in RA-ILD and RA-bronchiectasis. Currently, there are no clear treatment guidelines. The treatments are now focusing on using a combination of immunosuppression and antifibrotic agents. Combination treatment targets both the fibrotic and inflammatory components of the disease process. Further studies are needed to identify the use of ACPA as a biomarker to tailor the treatment in RA-ILD and RA-bronchiectasis.