Pneumococcal vaccination of elderly adults: new paradigms for protection

The effectiveness of revaccination with pneumococcal polysaccharide vaccine for preventing pneumococcal disease in older adults in England: A population-based cohort study

BACKGROUND

Pneumococcal disease in older adults in the United Kingdom is rising despite immunisation. A key gap in the literature is the clinical effectiveness of revaccination with the pneumococcal polysaccharide vaccine (PPV23).

METHODS

A cohort study was performed in England, using electronic medical records in the Clinical Practice Research Datalink. Individuals aged ≥64 years and vaccinated with PPV23 were included. Rates of hospitalised pneumonia (HP) and invasive pneumococcal disease (IPD) were compared between individuals receiving a single PPV23 dose versus those receiving two doses using multi-level Cox proportional hazards models. Propensity score weighting was performed to minimise the effect of confounding covariates across the comparison groups.

RESULTS

Between 2006 and 2019, there were 462 505 eligible participants. Of those, 6747 (1·5 %) received revaccination. Two doses compared to one dose was associated with an increased risk of HP (adjusted Hazard Ratio [aHR] 1·95; 95 %CI 1·74-2·20) and IPD (aHR 1·44; 95 %CI 1·41-1·46). In participants aged 64-74 years PPV23 revaccination was associated with more IPD (aHR 2·02; 95 %CI 1·75-2·33) and HP (aHR 1·46; 95 %CI 1·42-1.49). In those aged ≥75 years PPV23 revaccination was associated with more HP (aHR 1·12; 95 %CI 1·08-1·16) with no statistically significant difference detected in risk of IPD (aHR 1·20; 95 %CI 0·94-1·52).

CONCLUSIONS

No clear benefit of PPV23 revaccination was measured in older adults in this observational study. The small proportion of revaccinated subjects limits the strength of the conclusions. Further research evaluating the clinical effectiveness of PPV23 revaccination is required.

Distinct baseline immune characteristics associated with responses to conjugated and unconjugated pneumococcal polysaccharide vaccines in older adults

Pneumococcal infections cause serious illness and death among older adults. The capsular polysaccharide vaccine PPSV23 and conjugated alternative PCV13 can prevent these infections; yet, underlying immunological responses and baseline predictors remain unknown. We vaccinated 39 older adults (>60 years) with PPSV23 or PCV13 and observed comparable antibody responses (day 28) and plasmablast transcriptional responses (day 10); however, the baseline predictors were distinct. Analyses of baseline flow cytometry and bulk and single-cell RNA-sequencing data revealed a baseline phenotype specifically associated with weaker PCV13 responses, which was characterized by increased expression of cytotoxicity-associated genes, increased frequencies of CD16+ natural killer cells and interleukin-17-producing helper T cells and a decreased frequency of type 1 helper T cells. Men displayed this phenotype more robustly and mounted weaker PCV13 responses than women. Baseline expression levels of a distinct gene set predicted PPSV23 responses. This pneumococcal precision vaccinology study in older adults uncovered distinct baseline predictors that might transform vaccination strategies and initiate novel interventions.

Unique Changes in the Incidence of Acute Chest Syndrome in Children With Sickle Cell Disease Unravel the Role of Respiratory Pathogens: A Time Series Analysis

BACKGROUND

Acute chest syndrome (ACS) is a life-threatening complication of sickle cell disease (SCD). Although respiratory pathogens are frequently detected in children with ACS, their respective role in triggering the disease is still unclear. We hypothesized that the incidence of ACS followed the unprecedented population-level changes in respiratory pathogen dynamics after COVID-19-related nonpharmaceutical interventions (NPIs).

RESEARCH QUESTION

What is the respective role of respiratory pathogens in ACS epidemiology?

STUDY DESIGN AND METHODS

This study was an interrupted time series analysis of patient records from a national hospital-based surveillance system. All children aged < 18 years with SCD hospitalized for ACS in France between January 2015 and May 2022 were included. The monthly incidence of ACS per 1,000 children with SCD over time was analyzed by using a quasi-Poisson regression model. The circulation of 12 respiratory pathogens in the general pediatric population over the same period was included in the model to assess the fraction of ACS potentially attributable to each respiratory pathogen.

RESULTS

Among the 55,941 hospitalizations of children with SCD, 2,306 episodes of ACS were included (median [interquartile range] age, 9 [5-13] years). A significant decrease was observed in ACS incidence after NPI implementation in March 2020 (-29.5%; 95% CI, -46.8 to -12.2; P = .001) and a significant increase after lifting of the NPIs in April 2021 (24.4%; 95% CI, 7.2 to 41.6; P = .007). Using population-level incidence of several respiratory pathogens, Streptococcus pneumoniae accounted for 30.9% (95% CI, 4.9 to 56.9; P = .02) of ACS incidence over the study period and influenza 6.8% (95% CI, 2.3 to 11.3; P = .004); other respiratory pathogens had only a minor role.

INTERPRETATION

NPIs were associated with significant changes in ACS incidence concomitantly with major changes in the circulation of several respiratory pathogens in the general population. This unique epidemiologic situation allowed determination of the contribution of these respiratory pathogens, in particular S pneumoniae and influenza, to the burden of childhood ACS, highlighting the potential benefit of vaccine prevention in this vulnerable population.

Pneumococcal bacteraemia in adults over a 10-year period (2011-2020): a clinical and serotype analysis

BACKGROUND

Streptococcus pneumoniae (pneumococcus) is a human nasopharyngeal tract coloniser responsible for invasive pneumococcal disease, which is largely vaccine preventable. Vaccination is recommended from birth for all, and through adulthood for those with risk conditions.

AIMS

To describe the clinical and serotype analysis of pneumococcus bacteraemia over a 10-year period.

METHODS

A 10-year (February 2011-December 2020) retrospective review was performed on all adult (age ≥18 years) pneumococcus bacteraemia presenting to the four public hospitals in Western Sydney, Australia. Comorbidities and risk factors were recorded.

RESULTS

Three hundred unique episodes of S. pneumoniae bloodstream infection (SPBI) were identified during the study period. The median age for SPBI was 63 years with 31.7% aged 70 years or older. A 94.7% had one or more risks factors for SPBI. Pneumonia was reported in 80% of all SPBI, whereas meningitis was reported in 6% and infective endocarditis in <1%. Asplenia was noted in 2.4%. Seven- and 30-day mortality was 6.6% and 11.9%, with a higher 30-day mortality in those aged ≥70 years (24.4%). The serotype distribution showed 7-valent conjugate vaccine covered 11.0% of all isolates, whereas 13-valent conjugate vaccine (13vPCV) and a 23-valent polysaccharide vaccine (23vPPV) covered 41.7% and 69.0% respectively. Immunisation details were available for 110 individuals, of whom, only 7.3% had received pneumococcal vaccination.

CONCLUSIONS

Most patients with pneumococcal bacteraemia had age- or comorbidity-related risk factors but were not vaccinated. Two-thirds of cases occurred in people aged <70 years. 13vPCV and 23vPPV covered 41.7% and 69.0% of bacteraemic isolates.

Distinct baseline immune characteristics associated with responses to conjugated and unconjugated pneumococcal polysaccharide vaccines in older adults

Pneumococcal infections cause serious illness and death among older adults. A capsular polysaccharide vaccine PPSV23 (Pneumovax®) and a conjugated polysaccharide vaccine PCV13 (Prevnar®) are used to prevent these infections, yet underlying responses, and baseline predictors remain unknown. We recruited and vaccinated 39 older adults (>60 years) with PPSV23 or PCV13. Both vaccines induced strong antibody responses at day 28 and similar plasmablast transcriptional signatures at day 10, however, their baseline predictors were distinct. Analyses of baseline flow cytometry and RNA-seq data (bulk and single cell) revealed a novel baseline phenotype that is specifically associated with weaker PCV13 responses, characterized by i) increased expression of cytotoxicity-associated genes and increased CD16+ NK frequency; ii) increased Th17 and decreased Th1 cell frequency. Men were more likely to display this cytotoxic phenotype and mounted weaker responses to PCV13 than women. Baseline expression levels of a distinct gene set was predictive of PPSV23 responses. This first precision vaccinology study for pneumococcal vaccine responses of older adults uncovered novel and distinct baseline predictors that might transform vaccination strategies and initiate novel interventions.

Acute organ injury and long-term sequelae of severe pneumococcal infections

Streptococcus pneumoniae (Spn) is a major public health problem, as it is a main cause of otitis media, community-acquired pneumonia, bacteremia, sepsis, and meningitis. Acute episodes of pneumococcal disease have been demonstrated to cause organ damage with lingering negative consequences. Cytotoxic products released by the bacterium, biomechanical and physiological stress resulting from infection, and the corresponding inflammatory response together contribute to organ damage accrued during infection. The collective result of this damage can be acutely life-threatening, but among survivors, it also contributes to the long-lasting sequelae of pneumococcal disease. These include the development of new morbidities or exacerbation of pre-existing conditions such as COPD, heart disease, and neurological impairments. Currently, pneumonia is ranked as the 9^th leading cause of death, but this estimate only considers short-term mortality and likely underestimates the true long-term impact of disease. Herein, we review the data that indicates damage incurred during acute pneumococcal infection can result in long-term sequelae which reduces quality of life and life expectancy among pneumococcal disease survivors.

Costs implications of pneumococcal vaccination of adults aged 30-60 with a recent diagnosis of diabetes

OBJECTIVE

The 23-valent pneumococcal polysaccharide vaccine is routinely recommended for adults with diabetes, but little is known about adherence to this recommendation and how vaccination of these adults affects costs related to pneumococcal disease.

RESEARCH DESIGN AND METHODS

We used data from a commercial insurance claims dataset to examine a cohort of non-elderly adults with a new diagnosis of diabetes and adults with no diagnosis of diabetes from 2005 to 2014. We examined rates of pneumococcal polysaccharide vaccination and the relationship between vaccination and pneumococcal disease costs, comparing results for persons with a diagnosis of diabetes and those with no diagnosis of diabetes.

RESULTS

Overall rates of pneumococcal polysaccharide vaccination among adults 30-60 years old were <1%/year. Rates of pneumococcal polysaccharide vaccination were higher for adults with diabetes. Pneumococcal polysaccharide vaccination rates more than doubled from 2.9% per year in 2005 to 6.0% per year in 2014 for adults vaccinated during the same year as their diabetes diagnosis. Using a two-part differences-in-differences model on a propensity-score matched dataset, pneumococcal polysaccharide vaccination may reduce average annual per-person pneumococcal disease costs by $90.54 [95% CI: $183.59, -$2.49, (p = 0.056)] in persons with diabetes from two years before to two years after vaccination.

CONCLUSIONS

Non-elderly adults with diabetes have low but rising rates of pneumococcal polysaccharide vaccination. Pneumococcal polysaccharide vaccination has a modest impact reducing overall costs of pneumococcal disease in this population.

Factors associated with pneumococcal vaccine uptake in elderly subjects referred to the respiratory department

Streptococcus pneumoniae is the most common pathogen for community-acquired pneumonia and is also common in nursing and healthcare-associated pneumonia. Pneumococcal vaccine shows clinical benefit and 23-valent pneumococcal polysaccharide vaccine (PPSV23) has been introduced in a routine immunization program in Japan. However, uptake of PPSV23 remains low, at 40%. One opportunity for capturing unvaccinated subjects is hospital referrals. Identifying factors associated with pneumococcal vaccination among referred subjects is thus important so that pulmonologists can maximize the capture of unvaccinated subjects. We retrospectively reviewed the records of subjects with a first referral to the Department of Respiratory Medicine at Hiratsuka City Hospital from September 2017 to March 2018. Subjects who were ≥65 years old and lived in Hiratsuka were included in this study. We compared the backgrounds of subjects and investigated factors associated with pneumococcal vaccination. A total of 142 individuals were included in this study and the pneumococcal vaccination rate was 44.4% (95% confidence interval (CI), 36.0–52.9%). Of these, 127 subjects regularly visited clinics and/or hospitals for any diseases and their pneumococcal vaccine rate was 44.1% (95%CI, 35.3–53.2%). In multivariate analysis, chronic respiratory diseases (odds ratio 5.7; 95%CI, 2.2–14.9, P<0.001) and receipt of PPSV23 notification (odds ratio 8.5; 95%CI, 2.5–29.0, P<0.001) were positively associated with pneumococcal vaccination. In conclusion, chronic respiratory diseases and receipt of PPSV23 notification were positively associated with pneumococcal vaccination. However, pneumococcal vaccination rates remain relatively low, even in subjects regularly visiting clinics and/or hospitals.

Investigation of novel cyclic structure in glycoconjugate using a simple model system

Bacterial capsular polysaccharide protein conjugates are a major class of vaccines for preventing severe bacterial infections. The conjugation of a polysaccharide to a carrier protein is critical for inducing adaptive immune response in healthy humans. Due to the high molecular mass and extensive structural heterogeneity of the glycoconjugate, the underlying sugar linkages and polypeptide site selectivity of the conjugation reaction are not well characterized and understood. Here, we report a model conjugation study using a monosaccharide and a synthetic peptide to investigate the fundamental reductive amination chemistry, which is one of the most commonly utilized conjugation strategies for glycoconjugate vaccines. We identified a cyclic tertiary amine linkage as the primary conjugation linkage for monosaccharides containing dialdehydes. Such linkage is previously not well-recognized by the glycoconjugate vaccine field. Our study has provided insights into this commonly used, yet complex conjugation chemistry and will benefit the design of future protein-polysaccharide-based vaccines.

Immunization with Recombinant Pneumolysin Induces the Production of Antibodies and Protects Mice in a Model of Systemic Infection Caused by Streptococcus pneumoniae

Immunogenic and protective activity of recombinant pneumolysin was studied in experiments on male BALB/c mice. The mice were immunized intraperitoneally with recombinant pneumolysin sorbed on Al(OH)₃ (200 μg per mouse). In 2 weeks after immunization, the isotypes of antibodies to recombinant pneumolysin in the serum of immunized mice were determined by ELISA. The animals were infected with Streptococcus pneumoniae serotype 3. Immunization with recombinant pneumolysin induced the production of anti-pneumolysin antibodies, mainly of IgG1 subisotype. On day 21 after intraperitoneal infection with S. pneumoniae serotype 3 in a dose of 10⁶ microbial cells, the survival rate of animals immunized with recombinant pneumolysin in a dose of 25 μg/mouse was 67% vs. 0% in the control (p<0.001). Recombinant pneumolysin could be considered as a promising protective antigen for inclusion in the serotype-independent vaccine against S. pneumoniae.

Antibody Treatment against Angiopoietin-Like 4 Reduces Pulmonary Edema and Injury in Secondary Pneumococcal Pneumonia

Secondary bacterial lung infection by Streptococcus pneumoniae (S. pneumoniae) poses a serious health concern, especially in developing countries. We posit that the emergence of multiantibiotic-resistant strains will jeopardize current treatments in these regions. Deaths arising from secondary infections are more often associated with acute lung injury, a common consequence of hypercytokinemia, than with the infection per se Given that secondary bacterial pneumonia often has a poor prognosis, newer approaches to improve treatment outcomes are urgently needed to reduce the high levels of morbidity and mortality. Using a sequential dual-infection mouse model of secondary bacterial lung infection, we show that host-directed therapy via immunoneutralization of the angiopoietin-like 4 c-isoform (cANGPTL4) reduced pulmonary edema and damage in infected mice. RNA sequencing analysis revealed that anti-cANGPTL4 treatment improved immune and coagulation functions and reduced internal bleeding and edema. Importantly, anti-cANGPTL4 antibody, when used concurrently with either conventional antibiotics or antipneumolysin antibody, prolonged the median survival of mice compared to monotherapy. Anti-cANGPTL4 treatment enhanced immune cell phagocytosis of bacteria while restricting excessive inflammation. This modification of immune responses improved the disease outcomes of secondary pneumococcal pneumonia. Taken together, our study emphasizes that host-directed therapeutic strategies are viable adjuncts to standard antimicrobial treatments.IMPORTANCE Despite extensive global efforts, secondary bacterial pneumonia still represents a major cause of death in developing countries and is an important cause of long-term functional disability arising from lung tissue damage. Newer approaches to improving treatment outcomes are needed to reduce the significant morbidity and mortality caused by infectious diseases. Our study, using an experimental mouse model of secondary S. pneumoniae infection, shows that a multimodal treatment that concurrently targets host and pathogen factors improved lung tissue integrity and extended the median survival time of infected mice. The immunoneutralization of host protein cANGPTL4 reduced the severity of pulmonary edema and damage. We show that host-directed therapeutic strategies as well as neutralizing antibodies against pathogen virulence factors are viable adjuncts to standard antimicrobial treatments such as antibiotics. In view of their different modes of action compared to antibiotics, concurrent immunotherapies using antibodies are potentially efficacious against secondary pneumococcal pneumonia caused by antibiotic-resistant pathogens.

Environmental factors which can affect the burden of pneumococcal disease and the immune response to pneumococcal vaccines: the need for more precisely delineated vaccine recommendations

Introduction: Precision medicine describes the customization of healthcare tailored to the individual patient. Generally, vaccines are considered as public health tools rather than from the individual patient perspective. However, adult vaccination programs in particular should consider many different factors, at the individual level and also from societal, cultural and country-specific perspectives. Currently, most immunization programs, including those for pneumococcal vaccines, have only been adopted on the basis of age or medical risk. Areas covered: Based on a broad literature search, this review addresses possible environmental factors which can affect the burden of pneumococcal disease and the immune response to pneumococcal vaccines. Expert opinion: Factors which influence the incidence of pneumococcal disease and the reaction against pneumococcal vaccination, including personal conditions, geographic/ethnic factors and social risks, are diverse. To maximize the effects of pneumococcal vaccination, not only for public health but also to induce optimal effects at the individual level, vaccines need to be verified under diverse situations and with collaboration among relevant medical societies, governments, and the pharmaceutical industry. Whereas vaccines are generally considered only from the public health perspective, flexible, comprehensive and tailored pneumococcal immunization programs, with appropriate policy support, can generate a greater positive impact on public health.

Assessing the function of pneumococcal neuraminidases NanA, NanB and NanC in in vitro and in vivo lung infection models using monoclonal antibodies

Streptococcus pneumoniae isolates express up to three neuraminidases (sialidases), NanA, NanB and NanC, all of which cleave the terminal sialic acid of glycan-structures that decorate host cell surfaces. Most research has focused on the role of NanA with limited investigations evaluating the roles of all three neuraminidases in host-pathogen interactions. We generated two highly potent monoclonal antibodies (mAbs), one that blocks the enzymatic activity of NanA and one cross-neutralizing NanB and NanC. Total neuraminidase activity of clinical S. pneumoniae isolates could be inhibited by this mAb combination in enzymatic assays. To detect desialylation of cell surfaces by pneumococcal neuraminidases, primary human tracheal/bronchial mucocilial epithelial tissues were infected with S. pneumoniae and stained with peanut lectin. Simultaneous targeting of the neuraminidases was required to prevent desialylation, suggesting that inhibition of NanA alone is not sufficient to preserve terminal lung glycans. Importantly, we also found that all three neuraminidases increased the interaction of S. pneumoniae with human airway epithelial cells. Lectin-staining of lung tissues of mice pre-treated with mAbs before intranasal challenge with S. pneumoniae confirmed that both anti-NanA and anti-NanBC mAbs were required to effectively block desialylation of the respiratory epithelium in vivo. Despite this, no effect on survival, reduction in pulmonary bacterial load, or significant changes in cytokine responses were observed. This suggests that neuraminidases have no pivotal role in this murine pneumonia model that is induced by high bacterial challenge inocula and does not progress from colonization as it happens in the human host.

Incidence and risk factors for invasive pneumococcal disease in HIV-positive individuals in the era of highly active antiretroviral therapy

Invasive pneumococcal diseases (IPDs) remain a significant cause of morbidity and mortality in human immunodeficiency virus (HIV)-positive individuals despite the widespread use of highly active antiretroviral therapy (HAART) and availability of pneumococcal vaccines. The aim of this study was to measure temporal trends in incidence and risk factors for IPD (defined as culture of Streptococcus pneumoniae from blood, cerebrospinal fluid or both) in a cohort of HIV-positive patients attending an ambulatory HIV care centre in Dublin, Ireland over a 10-year period 2006-2015. Incidence of IPD was determined as events per 100,000 person-years' follow-up. Poisson regression was used to assess linear trend in incidence over time. A nested case-control study (four controls per case) was undertaken to assess risk factors for IPD. Forty-seven episodes of IPD were identified in 42 HIV-positive individuals (median [IQR] age 38 years [33-43], 69% male, 86% injecting drug users (IDUs), median CD4 T-cell count 213 cells/mm³) over 16,008 person-years' follow-up (overall incidence rate 293/100,000 person-years). Three patients had two episodes and one patient had three episodes of IPD during the study period. The overall case fatality rate was 15% (95% confidence interval [CI] 4-24%). The incidence of IPD per 100,000 person-years decreased from 728 (95% CI, 455-1002), to 242 (95% CI, 120-365) to 82 (95% CI, 40-154) in calendar periods 2006-2008, 2009-2012 and 2013-2015, respectively (p < 0.01 for linear trend). Older age (p = 0.02), male gender (p = 0.05), detectable HIV viral load (p < 0.01) and non-receipt of pneumococcal vaccine (p = 0.03) were associated with IPD while IDU as risk of acquisition of HIV was of borderline significance (p = 0.06). HIV-positive individuals remain at greater risk of IPD compared to the general population. Pneumococcal vaccine should be seen as a priority to ensure optimal protection for HIV-positive patients.

Age-related changes in the levels and kinetics of pulmonary cytokine and chemokine responses to Streptococcuspneumoniae in mouse pneumonia models

Streptococcuspneumoniae is a major human pathogen at the extremes of age. The elderly are particularly vulnerable to S.pneumoniae, the most common causative agent of bacterial pneumonia in this population. Despite the availability of vaccines and antibiotics, mortality rates associated with pneumococcal pneumonia in this age group remain high. In light of globally increasing life-expectancy, a better understanding of the patho-mechanisms of elderly pneumococcal pneumonia, including alterations in innate immune responses, is needed to develop improved therapies. In this study we aimed at investigating how increased susceptibility to pneumococcal infection relates to inflammation kinetics in the aged mouse pneumonia model by determining pulmonary cytokine and chemokine levels and comparing these parameters to those measured in young adult mice. Firstly, we detected overall higher pulmonary cytokine and chemokine levels in aged mice. However, upon induction of pneumococcal pneumonia in aged mice, delayed production of certain analytes, such as IFN-γ, MIG (CXCL9), IP-10 (CXCL10), MCP-1 (CCL2), TARC (CCL17) and MDC (CCL22) became apparent. In addition, aged mice were unable to control excess inflammatory responses: while young mice showed peak inflammatory responses at 20 h and subsequent resolution by 48 h post intranasal challenge, in aged mice increasing cytokine and chemokine levels were measured. These findings highlight the importance of considering multiple time points when delineating inflammatory responses to S.pneumoniae in an age-related context. Finally, correlation between pulmonary bacterial burden and cytokine or chemokine levels in young mice suggested that appropriately controlled inflammatory responses support the host to fight pneumococcal infection.

Pneumococcal Disease and the Effectiveness of the PPV23 Vaccine in Adults: A Two-Stage Bayesian Meta-Analysis of Observational and RCT Reports

The efficacy of PPV-23 vaccine on outcomes of pneumococcal disease in adults still remains controversial due mainly to the lack of consistency between the results obtained from observational studies(OSs) and those obtained from randomized controlled trials(RCTs). As a consequence, the complexity in the structure of evidence available, in turn, generates a challenge for combining disparate pieces of evidence quantitatively. In this regard, we used a hierarchical Bayesian inference-based evidence synthesis of RCTs and observational data using a two-stage approach (in addition to a traditional random-effects meta-analysis) to examine the effectiveness of PPV-23 in adults. To this end, 21 studies were included involving 826109 adult participants. By a two-stage Bayesian meta-analysis, which was directly used for combining studies of different designs, the overall log OR (95% credible interval) for IPDs was -0.1048 (-0.3920,-0.0250), indicating a significant protective effect of the vaccination against IPDs. No significant effect of PPV-23 was found on all-cause pneumonia, pneumococcal pneumonia, and death from pneumonia, which confirmed the results obtained by a traditional method followed by stratified and sensitivity analyses. The estimated overall log OR (95% credible interval) was -0.0002 (-0.0241,0.0142), -0.0002 (-0.0110,0.0122), and -6.3912 × 10^-5 (-0.0219,0.0131), respectively. The PPV-23 vaccine might be effective in preventing the most severe invasive forms of pneumococcal diseases, but not effective in preventing other clinical outcomes, in the adult population of 18 years and older.

Anti-protein immunoglobulin M responses to pneumococcus are not associated with aging

Background

The incidence of community-acquired pneumonia and lower respiratory tract infection rises considerably in later life. Immunoglobulin M (IgM) antibody levels to pneumococcal capsular polysaccharide are known to decrease with age; however, whether levels of IgM antibody to pneumococcal proteins are subject to the same decline has not yet been investigated.

Methods

This study measured serum levels and binding capacity of IgM antibody specific to the pneumococcal surface protein A (PspA) and an unencapsulated pneumococcal strain in serum isolated from hospital patients aged < 60 and ≥ 60, with and without lower respiratory tract infection. A group of young healthy volunteers was used as a comparator to represent adults at very low risk of pneumococcal pneumonia. IgM serum antibody levels were measured by enzyme-linked immunosorbent assay (ELISA) and flow cytometry was performed to assess IgM binding capacity. Linear regression and one-way analysis of variance (ANOVA) tests were used to analyse the results.

Results

Levels and binding capacity of IgM antibody to PspA and the unencapsulated pneumococcal strain were unchanged with age.

Conclusions

These findings suggest that protein-based pneumococcal vaccines may provide protective immunity in the elderly.

Trial registration

The LRTI trial (LRTI and control groups) was approved by the National Health Service Research Ethics Committee in October 2013 (12/NW/0713). Recruitment opened in January 2013 and was completed in July 2013. Healthy volunteer samples were taken from the EHPC dose-ranging and reproducibility trial, approved by the same Research Ethics Committee in October 2011 (11/NW/0592). Recruitment for this study ran from October 2011 until December 2012. LRTI trial: (NCT01861184), EHPC dose-ranging and reproducibility trial: (ISRCTN85403723).

Systematic review of economic evaluations of the 23-valent pneumococcal polysaccharide vaccine (PPV23) in individuals 60 years of age or older

OBJECTIVES

To systematically review the economic evaluations of 23-valent pneumococcal polysaccharide vaccine (PPV23) in adults aged ≥60 years to inform the development of local studies through the discussion of parameters and assumptions that influence the results of the analyses.

METHODS

We searched the MEDLINE, Excerpta Medica, Cochrane Library, Latin-American and Caribbean Health Sciences Literature (LILACS), Brazilian Regional Library of Medicine, National Health Service Economic Evaluation, and Centre for Reviews and Dissemination-as well as the Scopus citation index and the Web of Science for full economic evaluations of PPV23 published up to March 2016. Two independent reviewers screened the articles for relevance and extracted the data. Main study characteristics and methods (clinical and epidemiological data, cost and incremental cost-effectiveness ratios (ICERs) were extracted and compared. Costs were updated to 2016 international dollars.

RESULTS

Twenty-seven studies published from 1980 to 2016 were reviewed. Most studies were conducted in Europe and the USA; three studies were conducted in Latin America (Brazil, 2; Colombia, 1). In addition to the scenario comparing the vaccination with the PPV23 to non-vaccination, three studies also compared PPV23 to pneumococcal conjugate 13-valent vaccine (PCV13). All studies used static models. Most used a lifetime (44.4%) or 5-6 year's time horizon (33.3%). Only three studies considered herd protection from children immunization with PCV13 in the model. Most studies considered PPV23 cost-effective (less than US$50,000 per LYG or QALY) and sometimes cost-saving (results ranging from cost-saving to US$84,636/QALY). The estimates of disease burden, the efficacy/effectiveness of PPV23, and the effects of herd protection from childhood immunization had most influence on the results.

CONCLUSIONS

Well-designed cost-effectiveness studies of PPV23 that represent the current epidemiological scenario and reduce uncertainty related to efficacy/effectiveness are extremely relevant to informing the decision-making process.

Dendritic cell-targeting DNA-based nasal adjuvants for protective mucosal immunity to Streptococcus pneumoniae

To develop safe vaccines for inducing mucosal immunity to major pulmonary bacterial infections, appropriate vaccine antigens (Ags), delivery systems and nontoxic molecular adjuvants must be considered. Such vaccine constructs can induce Ag-specific immune responses that protect against mucosal infections. In particular, it has been shown that simply mixing the adjuvant with the bacterial Ag is a relatively easy means of constructing adjuvant-based mucosal vaccine preparations; the resulting vaccines can elicit protective immunity. DNA-based nasal adjuvants targeting mucosal DCs have been studied in order to induce Ag-specific mucosal and systemic immune responses that provide essential protection against microbial pathogens that invade mucosal surfaces. In this review, initially a plasmid encoding the cDNA of Flt3 ligand (pFL), a molecule that is a growth factor for DCs, as an effective adjuvant for mucosal immunity to pneumococcal infections, is introduced. Next, the potential of adding unmethylated CpG oligodeoxynucleotide and pFL together with a pneumococcal Ag to induce protection from pneumococcal infections is discussed. Pneumococcal surface protein A has been used as vaccine for restoring mucosal immunity in older persons. Further, our nasal pFL adjuvant system with phosphorylcholine-keyhole limpet hemocyanin (PC-KLH) has also been used in pneumococcal vaccine development to induce complete protection from nasal carriage by Streptococcus pneumoniae. Finally, the possibility that anti-PC antibodies induced by nasal delivery of pFL plus PC-KLH may play a protective role in prevention of atherogenesis and thus block subsequent development of cardiovascular disease is discussed.

Understanding the complications of anti-tumor necrosis factor therapy in East Asian patients with inflammatory bowel disease

Remarkable advances have been made in the treatment of inflammatory bowel disease since the introduction of anti-tumor necrosis factor-α agents, especially for patients who are refractory to or cannot tolerate conventional therapies. Currently, infliximab, adalimumab, and golimumab are available in the East Asian medical market, and these agents have been shown to be effective for inducing and maintaining long-term remission of inflammatory bowel disease. Despite their clinical benefits, anti-tumor necrosis factor therapy can also lead to increased vulnerability to infections, development of autoimmune diseases and malignancy, and decreased immunogenicity of vaccinations. Because infectious diseases, such as tuberculosis, hepatitis, and influenza, remain major health problems in East Asia, more cautious use of biologics is needed. To further improve treatment efficacy and safety, close monitoring of inflammation, regular surveillance for malignancy, and regularly scheduled vaccinations are needed. Treatment strategies for biologics should be customized to meet the needs of different patients.

Theory and strategy for Pneumococcal vaccines in the elderly

Pneumonia is the fourth-leading cause of death globally, and Streptococcus pneumoniae is the most important causative pathogen. Because the incidence of pneumococcal diseases is likely to increase with the aging society, we should determine an optimal strategy for pneumococcal vaccination. While consensus indicates that 23-valent pneumococcal polysaccharide vaccine prevents invasive pneumococcal diseases (IPD), its effects on community-acquired pneumonia (CAP) remain controversial. Recently, a 13-valent pneumococcal conjugate vaccine (PCV13) was released. The latest clinical study (CAPiTA study) showed that PCV13 reduced vaccine-type CAP and IPD. Based on these results, the Advisory Committee on Immunization Practices recommended initial vaccination with PCV13 for the elderly. Scientific evidence regarding immunosenescence is needed to determine a more ideal vaccination strategy for the elderly with impaired innate and adaptive immunity. Continuing research on the cost effectiveness of new vaccine strategies considering constantly changing epidemiology is also warranted.

Risk Factors for Pneumonia and the Effect of the Pneumococcal Vaccine in Patients With Chronic Airflow Obstruction

Background: To evaluate the risk factors for pneumonia and the efficacy of the pneumococcal polysaccharide vaccine (PPV) in patients with chronic airflow obstruction. Methods: We retrospectively studied the risk factors for pneumonia in 820 consecutive patients with chronic obstructive pulmonary disease (COPD) (n=509) and patients with asthma-COPD overlap syndrome (ACOS) (n=311). The effects of asthma, age, smoking history, chronic sputum, use of inhaled corticosteroids, percent predicted forced vital capacity (%FVC), percent predicted forced expiratory volume in 1 second (%FEV₁), body mass index (BMI), computed tomography (CT)-diagnosed emphysema, and the pneumococcal vaccination on the frequency of pneumonia were assessed. Results: There was no difference in the frequency of pneumonia in patients with COPD and those with ACOS. In a univariate analysis, age (p= 0.031), %FVC (p< 0.001), %FEV₁ (p < 0.001), BMI (p = 0.003), the presence of emphysema (p < 0.001) and a history of vaccination with the PPV (p = 0.034) were associated with the frequency of pneumonia. A multivariate analysis identified low BMI, the presence of emphysema and the absence of a pneumococcal vaccination as independent risk factors. The combination index of these factors, the BOVE index, which is calculated from low BMI (<22 kg/m²), low %FEV₁ (<60%), vaccination history and emphysema was associated with the overall frequency of pneumonia. Conclusions:The index of multidimensional risk factors is useful to predict the frequency of pneumonia in patients with chronic airflow obstruction. The pneumococcal vaccination was associated with significantly lower incidence of pneumonia.

Novel Strategy To Protect against Influenza Virus-Induced Pneumococcal Disease without Interfering with Commensal Colonization

Streptococcus pneumoniae commonly inhabits the nasopharynx as a member of the commensal biofilm. Infection with respiratory viruses, such as influenza A virus, induces commensal S. pneumoniae to disseminate beyond the nasopharynx and to elicit severe infections of the middle ears, lungs, and blood that are associated with high rates of morbidity and mortality. Current preventive strategies, including the polysaccharide conjugate vaccines, aim to eliminate asymptomatic carriage with vaccine-type pneumococci. However, this has resulted in serotype replacement with, so far, less fit pneumococcal strains, which has changed the nasopharyngeal flora, opening the niche for entry of other virulent pathogens (e.g., Streptococcus pyogenes, Staphylococcus aureus, and potentially Haemophilus influenzae). The long-term effects of these changes are unknown. Here, we present an attractive, alternative preventive approach where we subvert virus-induced pneumococcal disease without interfering with commensal colonization, thus specifically targeting disease-causing organisms. In that regard, pneumococcal surface protein A (PspA), a major surface protein of pneumococci, is a promising vaccine target. Intradermal (i.d.) immunization of mice with recombinant PspA in combination with LT-IIb(T13I), a novel i.d. adjuvant of the type II heat-labile enterotoxin family, elicited strong systemic PspA-specific IgG responses without inducing mucosal anti-PspA IgA responses. This response protected mice from otitis media, pneumonia, and septicemia and averted the cytokine storm associated with septic infection but had no effect on asymptomatic colonization. Our results firmly demonstrated that this immunization strategy against virally induced pneumococcal disease can be conferred without disturbing the desirable preexisting commensal colonization of the nasopharynx.

The clinical management of lower respiratory tract infections

The 2010 Global Burden of Disease Study reported that lower respiratory tract infections, including pneumonia, are the fourth most common cause of death globally. The etiology of acute bronchitis and asthma exacerbations is mostly viral and the therapy is symptomatic. Management decisions in community acquired pneumonia regarding site of care, extent of assessment, and level of treatment are based primarily on disease severity (outpatient, inpatient, ICU admission). Antibiotics are the main choice of treatment for patients with pneumonia, acute exacerbations (AE) of COPD (including increased sputum purulence and worsening shortness of breath) and AE of non-CF bronchiectasis. Inhaled antibiotics may represent a more optimal approach for the treatment and prevention of AE of non-CF bronchiectasis. Approved strategies for the prevention of exacerbations include smoking cessation and rehabilitation programs, drug therapy and vaccination.

[Pneumococcal vaccines. New conjugate vaccines for adults]

Pneumococcal infections are a significant cause of morbidity and mortality, and are one of the 10 leading causes of death worldwide. Children under 2 years have a higher incidence rate, followed by adults over 64 years. The main risk group are individuals with immunodeficiency, and those with anatomical or functional asplenia, but can also affect immunocompetent persons with certain chronic diseases. Significant progress has been made in the last 10 years in the prevention of these infections. Until a few years ago, only the 23-valent non-conjugate pneumococcal vaccine was available. Its results were controversial in terms of efficacy and effectiveness, and with serious limitations on the type of immune response induced. The current possibility of using the 13-valent conjugate vaccine in adults has led to greater expectations in improving the prevention of pneumococcal disease in these age groups.

Nanogel-based pneumococcal surface protein A nasal vaccine induces microRNA-associated Th17 cell responses with neutralizing antibodies against Streptococcus pneumoniae in macaques

We previously established a nanosized nasal vaccine delivery system by using a cationic cholesteryl group-bearing pullulan nanogel (cCHP nanogel), which is a universal protein-based antigen-delivery vehicle for adjuvant-free nasal vaccination. In the present study, we examined the central nervous system safety and efficacy of nasal vaccination with our developed cCHP nanogel containing pneumococcal surface protein A (PspA-nanogel) against pneumococcal infection in nonhuman primates. When [(18)F]-labeled PspA-nanogel was nasally administered to a rhesus macaque (Macaca mulatta), longer-term retention of PspA was noted in the nasal cavity when compared with administration of PspA alone. Of importance, no deposition of [(18)F]-PspA was seen in the olfactory bulbs or brain. Nasal PspA-nanogel vaccination effectively induced PspA-specific serum IgG with protective activity and mucosal secretory IgA (SIgA) Ab responses in cynomolgus macaques (Macaca fascicularis). Nasal PspA-nanogel-induced immune responses were mediated through T-helper (Th) 2 and Th17 cytokine responses concomitantly with marked increases in the levels of miR-181a and miR-326 in the serum and respiratory tract tissues, respectively, of the macaques. These results demonstrate that nasal PspA-nanogel vaccination is a safe and effective strategy for the development of a nasal vaccine for the prevention of pneumonia in humans.

Pneumococcal polysaccharide vaccination in rheumatoid arthritis patients receiving tacrolimus

Introduction

In rheumatoid arthritis (RA) patients receiving immunosuppressive treatments, vaccination against Streptococcus pneumoniae is recommended. The objective of the study was to evaluate the effects of tacrolimus (TAC) on immune response following administration of a 23-valent pneumococcal polysaccharide vaccine (PPSV23) in patients with established RA.

Methods

Patients with RA (n = 133) were vaccinated with PPSV23. Patients were classified into TAC (n = 29), methotrexate (MTX) (n = 55), control (n = 35), and TAC/MTX (n = 14) treatment groups. We measured the concentrations of pneumococcal serotypes 6B and 23F by using an enzyme-linked immunosorbent assay and determined antibody functionality by using a multiplexed opsonophagocytic killing assay, reported as the opsonization index (OI), before and 4 to 6 weeks after vaccination. A positive antibody response was defined as at least a twofold increase in the IgG concentration or as at least a 10-fold increase in the OI.

Results

IgG concentrations and OIs were significantly increased in all treatment groups after PPSV23 vaccination. The TAC treatment group appears to respond in a manner similar to that of the RA control group in terms of 6B and 23F serotype concentration and function. In contrast, the MTX group had the lowest immune response. Patients who received a combination of TAC and MTX (TAC/MTX) also had a diminished immune response compared with those who received TAC alone.

Conclusions

TAC monotherapy does not appear to impair PPSV23 immunogenicity in patients with RA, whereas antibody production and function may be reduced when TAC is used with MTX. Thus, PPSV23 administration during ongoing TAC treatment should be encouraged for infection-prone TAC-treated patients with rheumatic diseases.

Trial registration

University Hospital Medical Information Network Clinical Trials Registry: UMIN000009566. Registered 12 December 2012.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-015-0662-x) contains supplementary material, which is available to authorized users.

Prior pneumococcal and influenza vaccinations and in-hospital outcomes for community-acquired pneumonia in elderly veterans

BACKGROUND

Studies of adults hospitalized for community-acquired pneumonia (CAP) reported better outcomes associated with prior pneumococcal vaccination (PV), suggesting potential additional benefits of PV in hospitalized CAP patients. Influenza (flu) vaccination (FV) could independently/additively improve CAP outcomes in hospitalized patients.

OBJECTIVE

To examine the effect of prior PV and FV on in-hospital outcomes in elderly veterans hospitalized for CAP.

DESIGN

Retrospective cohort study.

SETTING AND PATIENTS

A total of 6,723 elderly veterans who were admitted to Veterans Affairs hospitals for CAP between October 1, 2002 and September 30, 2003.

INTERVENTION

PV in the 5 years and FV in the 1 year before admission.

MEASUREMENTS

The association of prior PV and/or FV with inpatient mortality and length of stay (LOS) (primary) and risk of any bacteremia and respiratory complications (secondary) were assessed using logistic regressions and generalized linear model, controlling for patient demographic and clinical characteristics.

RESULTS

Prior PV alone was not associated with shortened LOS, or reduced risk of inpatient mortality or respiratory complications. Lower risk of bacteremia was associated with prior PV (odds ratio: 0.66; 95% confidence interval [CI]: 0.48-0.90). After adjusting for patients' characteristics, risk of inpatient mortality was not statistically significantly different across the vaccination groups, but having had both PV and FV before CAP admission was associated with a 10% reduction in LOS (95% CI: 0.86-0.95) compared to having had neither vaccinations.

CONCLUSION

Significant survival benefit and improved in-hospital outcomes may not be expected among CAP-hospitalized elderly patients with prior PV alone. However, having both PV and FV before CAP admission may reduce LOS.

Pneumococcal vaccines: understanding centers for disease control and prevention recommendations

Streptococcus pneumoniae infection is a common and serious health problem that is best prevented by the pneumococcal vaccine. The first vaccine approved by the U.S. Federal Drug Administration in 1977 contained 14 polysaccharide antigens. An improved vaccine introduced in 1983 included 23 polysaccharide antigens. Both vaccines were effective for immunocompetent adults; however, young children and immunocompromised adults remained susceptible. A pediatric vaccine was developed consisting of the capsular antigens of seven pneumococcal serotypes commonly found in children. The antigens in this preparation are covalently conjugated to diphtheria protein to make them more antigenic. The conjugate vaccine was expanded to include 13 serotypes by 2010. Although more immunogenic, the conjugate vaccine has fewer serotypes than the older 23-valent vaccine. The U.S. Centers for Disease Control and Prevention recommend that children at risk for pneumococcal pneumonia as defined by the presence of chronic disease should receive the 13-valent conjugated vaccine. Adults at risk for pneumococcal pneumonia, which includes those over 65 years of age and those who have a chronic disease, should receive the 23-polysaccharide vaccine. Immunosuppressed patients of any age should receive both vaccines. Adults should be revaccinated once at age 65 years or older with the 23-polysaccharide vaccine provided that at least 5 years have elapsed since the previous vaccination.

Systems vaccinology: Enabling rational vaccine design with systems biological approaches

Vaccines have drastically reduced the mortality and morbidity of many diseases. However, vaccines have historically been developed empirically, and recent development of vaccines against current pandemics such as HIV and malaria has been met with difficulty. The advent of high-throughput technologies, coupled with systems biological methods of data analysis, has enabled researchers to interrogate the entire complement of a variety of molecular components within cells, and characterize the myriad interactions among them in order to model and understand the behavior of the system as a whole. In the context of vaccinology, these tools permit exploration of the molecular mechanisms by which vaccines induce protective immune responses. Here we review the recent advances, challenges, and potential of systems biological approaches in vaccinology. If the challenges facing this developing field can be overcome, systems vaccinology promises to empower the identification of early predictive signatures of vaccine response, as well as novel and robust correlates of protection from infection. Such discoveries, along with the improved understanding of immune responses to vaccination they impart, will play an instrumental role in development of the next generation of rationally designed vaccines.

Safety and tolerability of 13-valent pneumococcal conjugate vaccine in the elderly

BACKGROUND

In September 2011 the European Medical Agency authorized the use of 13-valent pneumococcal conjugate vaccine (PCV13) in adults aged ≥50 years. The same occurred in the US in December 2011 when the Food and Drug Administration approved the use of PCV13 in the same target age-group with indication for the prevention of invasive pneumococcal diseases and community acquired pneumonia sustained by the serotypes contained in the vaccine. The Liguria Region, in Italy, implemented in 2013 an active and free of charge immunization strategy with PCV13 among adults affected by specific risk conditions and the elderly aged ≥70 years.

METHODS

An observational study was performed in order to assess the safety and tolerability of PCV13 among elderly dwelling in the metropolitan area of Genoa, the capital city of Liguria Region. Eligible subjects, who received PCV13 following the public health immunization campaign at the Local Health Unit 3 of Genoa, provided a written informed consent to take part in the study. Eight-hundred-seventy-one subjects were enrolled between October 2013 and May 2014: all were monitored by qualified healthcare personnel for at least 30 min after vaccination at the outpatient clinics, in order to assess any possible sudden reaction. The occurrence of a series of local and systemic solicited reactions and of any unsolicited Adverse Events (AEs) was monitored using a self-administered clinical diary and by regular phone contacts up to 14 and 21 d following immunization, respectively. Moreover, a 6-months follow-up following vaccination was planned in order to monitor Severe Adverse Events (SAEs).

RESULTS

No sudden reaction occurred in vaccinees at the outpatient clinics. Pain (27.4%) was the most frequent reaction reported by subjects at the injection site, while new muscle pain (13.6%), fatigue (10.7%), and headache (9.9%) resulted the most common systemic reactions. Rates of the main reactions reported in this on-field study resulted generally lower than those registered in clinical trials performed in the elderly. The incidence of fever (2.2%) following vaccination was low at values superimposable to that reported in previous studies.

CONCLUSION

This observational study showed a good safety and tolerability of PCV13 among the elderly in routine clinical practice further confirming the evidence coming from clinical trials in the same age-group.

Pneumococcal vaccine and patients with pulmonary diseases

Chronic pulmonary diseases are chronic diseases that affect the airways and lung parenchyma. Examples of common chronic pulmonary diseases include asthma, bronchiectasis, chronic obstructive lung disease, lung fibrosis, sarcoidosis, pulmonary hypertension, and cor pulmonale. Pulmonary infection is considered a significant cause of mortality in patients with chronic pulmonary diseases. Streptococcus pneumoniae is the leading isolated bacteria from adult patients with community-acquired pneumonia, the most common pulmonary infection. Vaccination against S. pneumoniae can reduce the risk of mortality, especially from more serious infections in both immunocompetent and immunocompromised patients. Patients with chronic pulmonary diseases who take steroids or immunomodulating therapy (eg, methotrexate, anti-tumor necrosis factor inhibitors), or who have concurrent sickle cell disease or other hemoglobinopathies, primary immunodeficiency disorders, human immunodeficiency virus infection/acquired immunodeficiency syndrome, nephrotic syndrome, and hematologic or solid malignancies should be vaccinated with both 13-valent pneumococcal conjugate vaccine and the pneumococcal polysaccharide vaccine 23-valent.

Vaccinations in older adults with gastrointestinal diseases

Vaccines play a key role in the prevention of illness in the elderly, are cost effective, and generally safe. Hepatitis C, cirrhosis, autoimmune hepatitis, and inflammatory bowel disease are more prevalent than ever among older adults. Along with an age-related decline in immune system function (immunosenescence), these diseases make elderly individuals more susceptible to infections and more likely to experience a poor outcome relative to their younger counterparts. Vaccinations also appear to be less effective in the elderly, warranting research into different vaccination strategies such as booster vaccines, higher doses of vaccine, and measurement of antibody titers to guide vaccination.

Attributable healthcare utilization and cost of pneumonia due to drug-resistant streptococcus pneumonia: a cost analysis

BACKGROUND

The burden of disease due to S. pneumoniae (pneumococcus), particularly pneumonia, remains high despite the widespread use of vaccines. Drug resistant strains complicate clinical treatment and may increase costs. We estimated the annual burden and incremental costs attributable to antibiotic resistance in pneumococcal pneumonia.

METHODS

We derived estimates of healthcare utilization and cost (in 2012 dollars) attributable to penicillin, erythromycin and fluoroquinolone resistance by taking the estimate of disease burden from a previously described decision tree model of pneumococcal pneumonia in the U.S. We analyzed model outputs assuming only the existence of susceptible strains and calculating the resulting differences in cost and utilization. We modeled the cost of resistance from delayed resolution of illness and the resulting additional health services.

RESULTS

Our model estimated that non-susceptibility to penicillin, erythromycin and fluoroquinolones directly caused 32,398 additional outpatient visits and 19,336 hospitalizations for pneumococcal pneumonia. The incremental cost of antibiotic resistance was estimated to account for 4% ($91 million) of direct medical costs and 5% ($233 million) of total costs including work and productivity loss. Most of the incremental medical cost ($82 million) was related to hospitalizations resulting from erythromycin non-susceptibility. Among patients under age 18 years, erythromycin non-susceptibility was estimated to cause 17% of hospitalizations for pneumonia and $38 million in costs, or 39% of pneumococcal pneumonia costs attributable to resistance.

CONCLUSIONS

We estimate that antibiotic resistance in pneumococcal pneumonia leads to substantial healthcare utilization and cost, with more than one-third driven by macrolide resistance in children. With 5% of total pneumococcal costs directly attributable to resistance, strategies to reduce antibiotic resistance or improve antibiotic selection could lead to substantial savings.

The role of vaccination in preventing pneumococcal disease in adults

Pneumococcal infections, including pneumonia and invasive disease, are major sources of morbidity and mortality worldwide. Prevention of the first acquisition of Streptococcus pneumoniae through the use of vaccines represents an effective method to reduce the burden of the disease in both children and adults. Two vaccines are currently available in adults: a pneumococcal polysaccharide vaccine (PPV23) that includes 23 purified capsular polysaccharide antigens and a pneumococcal protein-conjugate vaccine (PCV13) that includes capsular polysaccharide antigens covalently linked to a non-toxic protein. The PPV23 induces a humoral immune response and since it has been licensed has been the subject of debates and controversies. Numerous studies and meta-analyses have shown that PPV23 protects against invasive pneumococcal disease, although there are conflicting data regarding its efficacy for the prevention of pneumonia. Vaccination with PCV13 stimulates good antibody responses as well as mucosal immunity and suppresses colonization. A conjugate vaccine can be expected to have benefits over a polysaccharide vaccine because of the characteristics of a T-cell-dependent response in terms of affinity, maturation of antibodies with repeated exposure, induction of immunological memory and long-lasting immunity. PCV13 has demonstrated all of these characteristics in children and fundamental differences in adults are not expected. The efficacy in adults is currently being investigated and results will be available soon.

Characterization of the inflammatory infiltrate in Streptococcus pneumoniae pneumonia in young and elderly patients

There is an increased susceptibility and mortality in the elderly due to pneumonia caused by Streptococcus pneumoniae. We aimed to assess the inflammatory cell composition with respect to age in pneumococcal pneumonia patients. Neutrophilic granulocytes and various lymphocyte and macrophage subpopulations were immunohistochemically quantified on lung tissue specimens of young (n = 5; mean age 8.4 years), middle-aged (n = 8; mean age 55.9 years) and elderly (n = 9; mean age 86.6 years) pneumonia patients with microbiologically proven S. pneumoniae pneumonia. We discovered a higher percentage of neutrophilic granulocytes in elderly as opposed to young patients (95 vs. 75%, p = 0.012). Conversely, young patients versus elderly patients had more alveolar macrophages (CD11c+: 20 vs. 9%, p = 0.029) and M1 macrophages (CD14+: 30 vs. 10%, p = 0.012 and HLA-DR+: 52 vs. 11%, p = 0.019). There was no significant difference concerning M2 macrophages and lymphocytes. Comparison of young patients with middle-aged patients showed similar significant results for alveolar macrophages (p = 0.019) and subsignificant results for M1 macrophages and neutrophilic granulocytes (p < 0.08). This is the first study characterizing the inflammatory infiltrate of pneumococcal pneumonia in situ. Our observations improve the understanding of the innate immune mechanisms of pneumococcal lung infection and point at the potential of therapies for restoring macrophage function and decreasing neutrophilic influx in order to help prevent or cure pneumonia.