The potential role for protein-conjugate pneumococcal vaccine in adults: what is the supporting evidence?

Constrained Optimization for Pneumococcal Vaccination in Brazil

OBJECTIVES

To identify the most cost-efficient combination of pneumococcal vaccines in infants and aging adults for a 10-year period in Brazil.

METHODS

Constrained optimization (CO) prioritized 9 pneumococcal vaccine regimens according to their gain in quality-adjusted life-years (QALYs) and their related costs over a prespecified time horizon with defined constraints for 2 age groups, infants and aging adults. The analysis starts from the current universal infant vaccination of pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV), 2 primary and 1 booster dose at 2, 4, and 12 months, respectively. Key constraints are the fixed annual vaccine budget increase and the relative return on investment (ROI_R) per regimen, which must be > 1, the reference intervention being the current vaccination strategy in infants and the most cost-efficient one in aging adults.

RESULTS

The CO analysis including all the constraints indicates that over 10 years the maximum extra health gain is 126 194 QALYs for an extra budget of $974 million Brazilian reals (ROI_R = 1.15). Results could be improved with a higher proportion of the at-risk population in aging adults, less herd effect, and better QALY scores.

CONCLUSION

The study shows that with 4 constraints on budget, time horizon, vaccine coverage, and cost efficiency, a CO analysis could identify the most cost-efficient overall pneumococcal vaccination strategy for Brazil, allowing for limited vaccine budget increase while obtaining appropriate health gain.

The Effect of a 13-Valent Conjugate Pneumococcal Vaccine on Circulating Antibodies Against Oxidized LDL and Phosphorylcholine in Man, A Randomized Placebo-Controlled Clinical Trial

Simple Summary

Atherosclerosis is the main underlying mechanism for cardiovascular disease. The main cause for atherosclerosis development is oxidized low density lipoprotein (oxLDL) accumulation in the vessel wall and a subsequent immune response. It has been established that immunoglobulin M antibodies against oxLDL help protect against atherosclerosis. It has been found in mice that vaccination with Streptococcus pneumoniae results in an increase of these protective antibodies and thereby decreases the development of atherosclerosis. In this study, we investigated if this increase of antibodies can be found in human as well. Twenty-four healthy male volunteers were vaccinated with Prevenar-13, a pneumococcal vaccine, using different dosing regimens. An increase in anti-Prevenar antibodies was found, showing that the vaccination worked. However, no increase in protective anti-phosphorylcholine or anti-oxLDL antibodies was observed. This work shows that vaccination against pneumococcal does not seem to be a suitable treatment option to help prevent atherosclerosis development, although further research would be required to test alternative pneumococcal-based vaccines, vaccination regimens or study populations.

Abstract

In mice vaccination with Streptococcus pneumoniae results in an increase in anti-oxLDL IgM antibodies due to mimicry of anti-phosphorylcholine (present in the cell wall of S. pneumoniae) and anti-oxLDL IgM. In this study we investigated the human translation of this molecular mimicry by vaccination against S. pneumoniae using the Prevenar-13 vaccine. Twenty-four healthy male volunteers were vaccinated with Prevenar-13, either three times, twice or once in a double-blind, placebo-controlled, randomized single center clinical study. Anti-pneumococcal wall, oxLDL and phosphorycholine antibody levels were measured at a fixed serum dilution, as well as circulating lipid levels over the course of 68 weeks. A significant increase in anti-oxLDL IgG and IgM was seen in the group receiving two doses six months apart compared to the placebo. However, these differences were not observed in the groups receiving a single dose, two doses one month apart, or three doses. This study shows that vaccination with Prevenar-13 does not result in robust anti-oxLDL IgM levels in humans. Further research would be required to test alternative pneumococcal-based vaccines, vaccination regimens or study populations, such as cardiovascular disease patients.

Early Intervention with Lenalidomide in Patients with High-risk Chronic Lymphocytic Leukemia

PURPOSE

Infectious complications constitute a leading cause of morbidity and mortality in chronic lymphocytic leukemia (CLL). Patients respond poorly to vaccines, particularly pneumococcal polysaccharide and influenza vaccines. In addition, patients with genetically high-risk disease are at increased risk for early disease progression and death. Lenalidomide, an oral immunomodulatory agent with demonstrated clinical activity in CLL, can potentially restore immune system dysfunction associated with CLL while improving disease outcomes.

PATIENTS AND METHODS

Phase II study randomized 49 patients with genetically high-risk CLL or small lymphocytic lymphoma [SLL; defined as unmutated Ig heavy chain variable region, deletion(17p) or (11q), and/or complex abnormal karyotype], to receive lenalidomide either concurrent (arm A) or sequential to (arm B) two doses of 13-valent protein-conjugated pneumococcal vaccine (PCV13) administered 2 months apart, in patients not meeting International Workshop on Chronic Lymphocytic Leukemia treatment criteria.

RESULTS

Four serotypes (3, 4, 5, 6B) achieved the additional seroprotection definition of a fourfold increase in arm A, and six serotypes (3, 4, 5, 6B, 19A, 19F) in arm B. All patients achieved the defined concentration of 0.35 μg/mL for at least one serotype tested. No significant difference was observed with the addition of lenalidomide. At median time on treatment of 3.6 years, median progression-free survival (PFS) was 5.8 years [95% confidence interval (CI), 3.1-not reached]. PFS at 1, 2, and 3 years was 85% (95% CI, 72-93), 79% (95% CI, 64-88), and 72% (95% CI, 57-83), respectively.

CONCLUSIONS

Lenalidomide is efficacious with manageable toxicities as an early intervention strategy in patients with high-risk CLL, but did not enhance humoral response to PCV13 vaccine.

Immunosenescence and human vaccine immune responses

The age-related dysregulation and decline of the immune system-collectively termed "immunosenescence"-has been generally associated with an increased susceptibility to infectious pathogens and poor vaccine responses in older adults. While numerous studies have reported on the clinical outcomes of infected or vaccinated individuals, our understanding of the mechanisms governing the onset of immunosenescence and its effects on adaptive immunity remains incomplete. Age-dependent differences in T and B lymphocyte populations and functions have been well-defined, yet studies that demonstrate direct associations between immune cell function and clinical outcomes in older individuals are lacking. Despite these knowledge gaps, research has progressed in the development of vaccine and adjuvant formulations tailored for older adults in order to boost protective immunity and overcome immunosenescence. In this review, we will discuss the development of vaccines for older adults in light of our current understanding-or lack thereof-of the aging immune system. We highlight the functional changes that are known to occur in the adaptive immune system with age, followed by a discussion of current, clinically relevant pathogens that disproportionately affect older adults and are the central focus of vaccine research efforts for the aging population. We conclude with an outlook on personalized vaccine development for older adults and areas in need of further study in order to improve our fundamental understanding of adaptive immunosenescence.

Adult vaccination for pneumococcal disease: a comparison of the national guidelines in Europe

Pneumococcal disease constitutes a major global health problem. Adults aged over 50 years and younger adults with specific chronic health conditions are at risk for invasive pneumococcal disease, associated with substantial morbidity and mortality. In Europe, two vaccine types are used in adults for pneumococcal immunization: pneumococcal polysaccharide vaccine (PPV23) and pneumococcal conjugate vaccine (PCV13). To provide an overview and to compare the national guidelines for pneumococcal immunization for adults in Europe. In November 2016, national guidelines on pneumococcal vaccination for adults of 31 European countries were obtained by Google search, the website of European Centre for Disease Prevention and Control, and contacting public health officials. In our analysis, we distinguished between age-based and risk-based guidelines. In October 2017, we used the same method to retrieve guideline updates. We observed great variability regarding age, risk groups, vaccine type, and use of boosters. In age-based guidelines, vaccination is mostly recommended in adults aged over 65 years using PPV23. Boosters are generally not recommended. An upper age limit for vaccination is reported in three countries. In the immunocompromised population, vaccination with both vaccines and administration of a booster is mostly recommended. In the population with chronic health conditions, there is more heterogeneity according vaccine type, sequence, and administration of boosters. Asplenia is the only comorbidity for which all countries recommend vaccination. The great variability in European pneumococcal vaccination guidelines warrants European unification of the guidelines for better control of pneumococcal disease.

Cost-Utility Study of PCV13 Versus PPSV23 in Adults in Chile

INTRODUCTION

Pneumococcal infections are a public health problem in older adults. In Chile there are two vaccines at this time, PPSV23 and PCV13. The first has lower immunogenicity and effectiveness in preventing pneumococcal pneumonia and a lower cost than PCV13.

OBJECTIVE

To determine the cost-effectiveness of PCV13 versus PPSV23 in adults 18 years old and over in the Chilean Health System.

MATERIAL AND METHOD

A cost-utility study was performed using the Markov model (population data for a time horizon of 10 years). Utilities and epidemiological data were obtained from the literature and costs from the Chilean Public sector. Vaccine's costs and quality-adjusted life years (QALYs) were determined and compared.

RESULTS

PCV13 vaccination program in adults (≥18 years), generated savings of $42,195 USD and an increase of 6,820 QALYs, avoiding 107 cases of bacteremia, 13 meningitis, 6,706 inpatient pneumonia, 4,509 outpatient pneumonia and 1,189 deaths compared to PPSV23 without variation on sensitivity analysis on high impact variables. For the subgroup of patients over 65 years old PCV13 generates savings of $ 32,105.94USD and produces 5,430 QALYs more compared to PPSV23.

CONCLUSION

PCV13 is dominant. A PCV13 vaccination program saves costs to the public system, reduces mortality and morbidity; these results are robust.

Growth Hormone (GH) Deficient Mice With GHRH Gene Ablation Are Severely Deficient in Vaccine and Immune Responses Against Streptococcus pneumoniae

The precise impact of the somatotrope axis upon the immune system is still highly debated. We have previously shown that mice with generalized ablation of growth hormone (GH) releasing hormone (GHRH) gene (Ghrh^−/−) have normal thymus and T-cell development, but present a marked spleen atrophy and B-cell lymphopenia. Therefore, in this paper we have investigated vaccinal and anti-infectious responses of Ghrh^−/− mice against S. pneumoniae, a pathogen carrying T-independent antigens. Ghrh^−/− mice were unable to trigger production of specific IgM after vaccination with either native pneumococcal polysaccharides (PPS, PPV23) or protein-PPS conjugate (PCV13). GH supplementation of Ghrh^−/− mice restored IgM response to PPV23 vaccine but not to PCV13 suggesting that GH could exert a specific impact on the spleen marginal zone that is strongly implicated in T-independent response against pneumococcal polysaccharides. As expected, after administration of low dose of S. pneumoniae, wild type (WT) completely cleared bacteria after 24 h. In marked contrast, Ghrh^−/− mice exhibited a dramatic susceptibility to S. pneumoniae infection with a time-dependent increase in lung bacterial load and a lethal bacteraemia already after 24 h. Lungs of infected Ghrh^−/− mice were massively infiltrated by inflammatory macrophages and neutrophils, while lung B cells were markedly decreased. The inflammatory transcripts signature was significantly elevated in Ghrh^−/− mice. In this animal model, the somatotrope GHRH/GH/IGF1 axis plays a vital and unsuspected role in vaccine and immunological defense against S. pneumoniae.

Pneumococcal conjugate vaccine triggers a better immune response than pneumococcal polysaccharide vaccine in patients with chronic lymphocytic leukemia A randomized study by the Swedish CLL group

AIM

To determine if patients with untreated chronic lymphocytic leukemia (CLL) benefit from vaccination with a 13-valent pneumococcal conjugated vaccine (PCV13), Prevenar13®, compared to a 23-valent pneumococcal polysaccharide vaccine (PPSV23), Pneumovax®, in terms of immune response.

BACKGROUND

Streptococcus pneumoniae causes substantial morbidity in patients with CLL, a group known to respond poorly to polysaccharide vaccines. Comparative studies with conjugated vaccines are lacking.

METHODS

128 treatment naïve CLL patients from eight hematology clinics in Sweden were randomized to vaccination with PCV13 (n = 63) or PPSV23 (n = 65) after stratification by IgG level and CLL clinical stage (Rai). Blood samples for evaluation of immune response were obtained at baseline, and at one and six months after vaccination. Analyses for each of the 12 pneumococcal serotypes common for PCV13 and PPSV23 were performed by opsonophagocytic assay (OPA) and enzyme-linked immunosorbent assay (ELISA).

RESULTS

PCV13 elicited a superior immune response than PPSV23 in 10/12 serotypes one month after vaccination and in 5/12 serotypes six months after vaccination, measured as OPA geometric mean titers (GMTs). Geometric mean concentrations of serotype-specific IgG antibodies elicited by PCV13 as measured by ELISA, were higher than those elicited by PPSV23 in half of the common serotypes, both after one and six months. PPSV23 did not trigger a better immune response than PCV13 for any of the serotypes, regardless of analysis method or time point of analysis. Negative predictive factors for vaccination response were hypogammaglobulinemia and long disease duration. Both vaccines were well tolerated.

CONCLUSIONS

In patients with previously untreated CLL, the efficacy of PCV13 in terms of immune response is superior to PPSV23 for most serotypes common for the two vaccines. We therefore propose that PCV13 should be included in vaccination programs against Streptococcus pneumoniae for CLL patients and administered as early as possible during the course of the disease.

Effectiveness and practical uses of 23-valent pneumococcal polysaccharide vaccine in healthy and special populations

Streptococcus pneumonia (S. pneumoniae) is responsible for significant morbidity and mortality throughout the world. The 23-valent pneumococcal polysaccharide vaccines (PPV23) have been widely used for many years, but challenges are remaining in some respects, especially for its effectiveness among high-risk populations and older adults. This review aims to summarize recent clinical trials and studies of PPV23 vaccination among healthy people ≥ 2 years of age and those with high-risk conditions such as pregnant women, individuals with immunocompromising diseases and other chronic conditions, and provide health officials in China and other developing countries a comprehensive understanding of the current vaccination strategies for PPV23 and for the combined use of PPV23 and pneumococcal conjugate vaccines (PCVs) in adults.

Nasopharyngeal Carriage of Streptococcus Pneumoniae and Serotypes Indentified among Nursing Home Residents in Comparison to the Elderly and Patients Younger than 65 Years Living in Domestic Environment

INTRODUCTION

In Slovenia, there is little data available on pneumococcal vaccination rates and no data on asymptomatic NPCR and serotypes in the population of nursing home residents in comparison to the elderly living in domestic environment, therefore the goal was to gain these data.

METHODS

A cross sectional epidemiological study was performed. Nasopharyngeal swabs from 151 nursing home residents, 150 elderly living in domestic environment, and 38 adults less than 65 years old were collected twice (in two consecutive years). The swabs were analysed for pneumococcal identification and serotyping. Patient data were collected from medical files and medical history.

RESULTS

No statistically significant differences in NPCR were seen between compared groups in two consecutive years. An average NPCR in two consecutive years in nursing home residents was 1.45%, in the elderly living in domestic environment 0.85%, and in adults less than 65 years old 7.05%. Serotypes identified among nursing home residents were 6B and 9N, among the group of elderly living in domestic environment, 6A and among adults less than 65 years old, 35F, 18C and 3. Pneumococcal vaccination rates were low (3.3% in nursing home residents, 6% in the elderly from domestic environment and 0% in the group of adults less than 65 years old).

CONCLUSIONS

Our data suggests that NPCR and the proportion of people vaccinated with pneumococcal vaccine among the elderly are low. We identified different serotypes in all groups, only one person was a chronic carrier (serotype 35F).

A case series evaluating the serological response of adult asthma patients to the 23-valent pneumococcal polysaccharide vaccine

BACKGROUND

Asthma is an independent risk factor for invasive pneumococcal disease; however, the immune response of adult asthma patients to pneumococcal vaccination is unknown. We explore the serologic response of patients with moderate to severe asthma to the 23-valent pneumococcal polysaccharide vaccine (PPSV23).

METHODS

Seventeen moderate to severe adult asthma patients that had not been vaccinated against pneumococcus over the 5 previous years were prospectively recruited from a tertiary care asthma clinic. Serum was analyzed for the presence of antibodies to five capsular polysaccharide (CP) antigens (6B, 9V, 19A, 19F, 23F) before and 4 weeks after PPSV23 vaccination.

RESULTS

There was a wide variability in baseline anti-CP antibody concentrations. Other than for serotype 19A, our patients frequently have baseline anti-CP antibody concentrations below 1 µg/mL (35% for serotype 19F, 41% for serotypes 9V and 23F, and 59% for serotype 6B). All post-vaccination geometric mean antibody concentrations were significantly higher than baseline. In the 31 tests where the baseline antibody concentration was <1 µg/mL, 77.4% had at least a twofold increase post-vaccination. Despite this, a large proportion of post-vaccination anti-CP antibody concentrations remained <1 µg/mL (51.6% of tests). Nine patients had at least one anti-CP antibody concentration <1 µg/mL post-vaccination. There was no difference between these patients and the remaining eight patients in demographic or clinical variables.

CONCLUSIONS

Patients with moderate to severe asthma have variable baseline and low post-vaccination antibody concentrations to common CP antigens included in the PPSV23 vaccine. The clinical relevance of these observations remains to be determined since the threshold concentration in adults required for clinical protection from invasive pneumococcal disease is uncertain.

Vaccine profile of PPV23: Beijing Minhai Biotech 23-valent pneumococcal vaccine

Introduction: Diseases caused by Streptococcus pneumoniae are a major public health problem worldwide, which can be effectively prevented by the 23-valent pneumococcal polysaccharide vaccines (PPV23).Areas covered: The Beijing Minhai PPV23 showed good safety and immunogenicity profiles in clinical trials. The immunogenicity of Beijing Minhai PPV23 was non-inferior to other licensed PPVs. Although PPV23 has been proved to be highly efficient and cost-effective, and was recommended for vaccination in high-risk populations in industrialized countries, the coverage of PPV23 vaccination was relatively low in developing countries.Expert commentary: The low vaccination proportions of PPV23 in China have not been improved in recent decades. Most of the populations with indications for receiving PPV23 were not aware of the possible benefits of PPV23. Moreover, PPV23 had some limitations, which called for the development of a new generation of vaccines against pneumococcal infection.

Epidemiology of invasive pneumococcal infections: manifestations, incidence and case fatality rate correlated to age, gender and risk factors

Background

Incidence, manifestations and case-fatality rate (CFR) of invasive pneumococcal disease (IPD) vary with age and comorbidities. New vaccines, changing age distribution, prolonged survival among immunocompromised patients and improved sepsis management have created a need for an update of basic facts to inform vaccine recommendations.

Methods

Age, gender and comorbidities were related to manifestations and death for 2977 consecutive patients with IPD in a Swedish region with 1.5 million inhabitants during 13 years before introduction of pneumococcal conjugate vaccines (PCV) in the infant vaccination program. These data were related to population statistics and prevalence of several comorbidities, and compared with two previous studies giving a total follow-up of 45 years in the same area.

Results

The annual incidence was 15/100,000 for any IPD and 1.1/100,000 for meningitis; highest among elderly followed by children < 2 years. It was 2238/100,000 among myeloma patients, followed by chronic lymphatic leukemia, hemodialysis and lung cancer, but not elevated among asthma patients. CFR was 10 % among all patients, varying from 3 % below 18 years to 22 % ≥ 80 years. During 45 years, the IPD incidence increased threefold and CFR dropped from 20 to 10 %. Meningitis incidence remained stable (1.1/100,000/year) but CFR dropped from 33 to 13 %. IPD-specific mortality decreased among children <2 years from 3.1 to 0.46/100,000/year but tripled among those ≥65 years.

Conclusions

IPD incidence and CFR vary widely between age and risk groups and over time even without general infant vaccination. Knowledge about specific epidemiological characteristics is important for informing and evaluating vaccination policies.

Should Committees That Write Guidelines and Recommendations Publish Dissenting Opinions?

Medical guidelines tend to convey a sense of unanimity of opinion that may not reflect the deliberations of the experts who wrote them. Using, as an example, an analysis of the recently published recommendations on administering pneumococcal conjugate vaccine to adults, the present article raises the question of whether official recommendations and guidelines should include dissenting opinions, analogous to decisions issued by the US Supreme Court. The argument that such a policy would lead to confusion in our profession is addressed in 2 ways: (1) the current system, in which different professional societies publish conflicting recommendations, as in the case of breast or prostate cancer screening, can be far more confusing, and (2) in the long run, greater transparency will lead to more thoughtful and higher-quality medical care. Perhaps the most important point of this paper is the suggestion that it is far better to bring dissent into the recommendation process than to act as if it is not there.

Clinical and microbiological implications of invasive pneumococcal disease in hospitalized patients (1998-2013)

INTRODUCTION

Infections caused by Streptococcus pneumoniae (pneumococcus) still represent a challenge for health systems around the world.

OBJECTIVE

The objective of this study was to assess microbiological and clinical aspects in hospitalized patients with invasive pneumococcus disease between 1998 and 2013.

MATERIALS AND METHODS

This was a retrospective study that analyzed the results of pneumococcus identification, serotyping, and susceptibility testing found in the Adolfo Lutz Institute databank. Personal variables, medical history and clinical outcome of patients admitted with invasive pneumococcal disease were analyzed. These were obtained from records of a public teaching hospital - Hospital das Clínicas Faculdade de Medicina Ribeirão Preto.

RESULTS

The sample comprised 332 patients. Patient age ranged from less than one month to 89 years old (mean 20.3 years) and the sample was predominately male. Pneumonia (67.8%) was the most common disease, accounting for 18.2% of deaths. Serotypes 14, 1, 3, 9V, 6B, 6A, 23F, 19A, 18C, 19F, 12F, and 4 were the most common (75.3%). Most patients, or 67.5%, were cured without any complication (success), 6.9% had some type of sequela (failure), and 25.6% died (failure). In the case of deaths due to meningitis, strains of fully penicillin resistant pneumococcus were isolated. Furthermore, 68.2% of patients who died presented some type of comorbidity. The 60 and older age group presented the most significant association (Odds Ratio=4.2), with outcome failure regardless of the presence of comorbidity. Serotype 18C was the most significant risk factor both in raw analysis (Odds Ratio=3.8) and when adjusted for comorbidity (Odds Ratio=5.0) or age (Odds Ratio=5.4). The same occurred with serotype 12F (respectively, Odds Ratio=5.1, Odds Ratio=5.0, and Odds Ratio=4.7) CONCLUSION: The present findings highlight the importance of IPD among young adults and older adults. In the era of conjugate vaccines, monitoring serotypes in different age groups is essential to assess the impact and adequacy of immunization.

Influence of Childhood Pneumococcal Conjugate Vaccines on Invasive Pneumococcal Disease in Adults With Underlying Comorbidities in Calgary, Alberta (2000-2013)

BACKGROUND

Pneumococcal conjugate vaccine (PCV) was introduced into Alberta, Canada's routine childhood immunization programs in 2002 (7-valent [PCV7]) and 2010 (13-valent [PCV13]). We assessed the effect of these programs on the epidemiology of invasive pneumococcal disease (IPD) to determine if PCV-associated indirect protection was relatively reduced in adults with underlying comorbidities.

METHODS

Demographic and clinical data were collected by a prospective, population-based surveillance system in Calgary, Alberta, Canada, from January 2000 to December 2013. An indirect cohort study design was used to assess for changes in the proportion of IPD cases with underlying comorbidities.

RESULTS

There were 1598 overall and 1346 adult IPD cases from 1 January 2000 to 31 December 2013. Overall IPD incidence decreased 33% (age 0-5 months), 86% (6-23 months), 67% (2-4 years), 26% (5-17 years), 22% (18-64 years), 36% (65-84 years), and 42% (≥85 years) from the prevaccine (January 2000-July 2002) to the post-PCV13 (July 2010-December 2013) period. Over the same timeframe, PCV7 serotype disease incidence declined to ≤1 case per 100 000 persons in all age groups. Neither the proportion of adult cases with immunocompetent comorbidities (relative risk ratio [RRR], 0.93; 95% confidence interval [CI], .62-1.40) nor immunocompromising comorbidities (RRR, 0.99; 95% CI, .61-1.61) differed between the pre-PCV period and post-PCV era.

CONCLUSIONS

Childhood PCV programs have provided considerable benefit, with substantial declines in overall and vaccine-serotype IPD in vaccinated children and in unvaccinated persons. Conjugate vaccine-associated indirect protection for adults with comorbidities was similar to that for healthy adults.

Quantitative and Functional Antibody Responses to the 13-Valent Conjugate and/or 23-Valent Purified Polysaccharide Vaccine in Aging HIV-Infected Adults

BACKGROUND

The number of aging human immunodeficiency virus-infected (HIV+) individuals living in the United States has substantially grown over the past two decades. Advanced age and HIV infection both increase susceptibility to Streptococcus pneumoniae infection due to B cell dysfunction. The combined impact of these factors on pneumococcal vaccine responses remains unknown.

METHODS

We assessed serum immunoglobulin (Ig) G and IgM levels and opsonophagocytic killing assay (OPA) titers to pneumococcal serotypes 14 and 23F in HIV+ subjects and HIV-uninfected (HIV-) controls 50-65 years old. HIV+ individuals with CD4⁺ T cells/μl (CD4) >200 and ≥1 year of antiretroviral therapy (ART) received either a dose of the 13-valent pneumococcal conjugate vaccine followed by the 23-valent pneumococcal polysaccharide vaccine 8 weeks later (PCV/PPV) as currently recommended (n=15) or a single dose of PPV only (n=22). HIV- controls received PCV/PPV (n=14).

RESULTS

HIV+ PCV/PPV and PPV groups exhibited similar increases in IgG levels and OPA titers for both serotypes after immunization. Postvaccination IgM levels for serotype 23F, but not 14, were significantly higher in HIV+ PCV/PPV compared to PPV groups. IgG and IgM levels for serotype 14 and OPA titers to serotype 23F were significantly reduced in HIV+ compared to HIV- PCV/PPV groups. Serotype-specific IgG levels correlated with OPA titers for all groups.

CONCLUSIONS

Our data suggest that the recommended PCV/PPV regimen may not significantly improve quantitative or functional antibody responses compared to PPV only in aging HIV+ subjects. Continued efforts aimed at improving vaccine responses in this high risk population are warranted.

Why the recent ACIP recommendations regarding conjugate pneumococcal vaccine in adults may be irrelevant

The Advisory Committee on Immunization Practices of the US Centers for Disease Control (ACIP) has recently recommended the 13-valent protein-conjugate pneumococcal vaccine (PCV13) for routine use in adults age 18-65 who have immunocompromising conditions as well as in all adults over the age of 65. By comparison to 23-valent pneumococcal polysaccharide vaccine (PPSV23), antibody responses to PCV13 are similar or modestly better one month after vaccination. The implication that PCV13 will provide more persistent immunity has been disproven; 12 months later, recipients of PPSV23 or PCV13 have identical anti-pneumococcal activity. The theoretical concept that a protein-based vaccine will be followed by a booster effect when pure polysaccharide antigens are administered is based on remarkably little evidence. The strongest objection to the current recommendations is that, since PCVs stimulate mucosal antibodies, the widespread use of these PCVs has led to a near-disappearance of vaccine serotypes from the population. This phenomenon has been amply documented for PCV7, and PCV13 is well on its way to doing the same. Thus, as US physicians are convincing their adult patients to receive 2 "pneumonia shots" instead of one, the use of PCV13 in the USA is rapidly becoming irrelevant.

Overwhelming Postsplenectomy Infection: A Prospective Multicenter Cohort Study

BACKGROUND

Recent population-based cohort studies have questioned the role of pneumococci as the most frequent pathogen causing severe infection in patients after splenectomy. The aim of the study was to define the causative pathogens and clinical presentation of patients with overwhelming postsplenectomy infection (OPSI).

METHODS

In a prospective cohort study in 173 German intensive care units, we searched for patients with and without asplenia and community-acquired severe sepsis/septic shock. Clinical and laboratory variables and survival of patients were assessed.

RESULTS

Fifty-two patients with severe sepsis or septic shock with asplenia and 52 without asplenia were included. OPSI patients more often had a history of malignancy (38% vs 17%; P = .016) and had a lower body mass index (24 kg/m(2) vs 28 kg/m(2); P = .004). Streptococcus pneumoniae was detected more frequently in OPSI patients (42% vs 12% without asplenia; P < .001) and more frequently manifested as bloodstream infection (31% vs 6%; P = .002). Gram-negative infection was similar in both groups (12% vs 19%; P = .157). Pneumococcal vaccine coverage of OPSI patients was low overall (42% vs 8% among patients without asplenia; P < .001). Purpura fulminans was a frequent complication, developing in 19% of OPSI patients vs 5% of patients without asplenia (P = .038). The interval between splenectomy and OPSI was 6 years (range, 1 month-50 years). On multivariable Poisson regression, asplenia was the only predictive variable independently associated with pneumococcal sepsis (adjusted relative risk, 2.53 [95% confidence interval, 1.06-6.08]).

CONCLUSIONS

Pneumococcal infections remain the most important cause of severe sepsis and septic shock following splenectomy.

Community-acquired pneumonia: An overview

Community-acquired pneumonia is still a significant cause of morbidity and mortality and is often misdiagnosed and inappropriately treated. Although it can be caused by a wide variety of micro-organisms, the pneumococcus, atypicals, such as Mycoplasma pneumoniae and Chlamydophila pneumoniae,Staphylococcus aureus and certain Gram-negative rods are the usual pathogens encountered. The site-of-care decision is critical in determining the site and type of care as well as the extent of diagnostic workup. Antimicrobial therapy should be started as soon as possible particularly in those requiring admission to hospital, but typically the physician does not know with any degree of certainty the identity of the etiologic pathogen. A number of national guidelines have been published to help the physician with this choice. The initial drug(s) can be modified if necessary if the pathogen and its antimicrobial susceptibility pattern becomes known. Adjunctive therapy such as pressors and fluid replacement are of value and macrolides appear to help as well, likely secondary to their immunomodulatory effects. Recent data also suggest a role for steroids.

Quantitative and Qualitative Antibody Responses to Immunization With the Pneumococcal Polysaccharide Vaccine in HIV-Infected Patients After Initiation of Antiretroviral Treatment: Results From a Randomized Clinical Trial

BACKGROUND

Pneumococcal vaccination is recommended for human immunodeficiency virus-infected (HIV+) persons; the best timing for immunization with respect to initiation of antiretroviral therapy (ART) is unknown.

METHODS

Double-blind, placebo-controlled trial in HIV+ with CD4(+) T cells/µL (CD4) ≥ 200 randomized to receive the 23-valent pneumococcal polysaccharide vaccine (PPV23) or placebo at enrollment, followed by placebo or PPV23, respectively, 9-12 months later (after ≥6 months of ART). Capsular polysaccharide-specific immunoglobin (Ig) G and IgM levels to serotypes 1, 3, 4, 6B, and 23F, and opsonophagocytic killing activity (OPA) to serotypes 6B and 23F were evaluated 1 month postvaccination.

RESULTS

One hundred seven subjects were enrolled, 72 (67.3%) were evaluable (36/group). Both groups had significant increases in pre- to 1-month postvaccination IgG levels, but negligible to IgM, and significant increases in OPA titers to serotype 6B but not to 23F. There were no significant differences between groups in serotype-specific IgM or IgG levels or OPA titers. For the combined groups, there was a significant correlation between serotype-specific IgG and OPA titers to 23F but not to 6B. There was no correlation between CD4, viral load and IgG responses.

CONCLUSIONS

In HIV+ with CD4 ≥ 200, delaying PPV23 until ≥6 months of ART does not improve responses and may lead to missed opportunities for immunization.

Cost-effectiveness of vaccinating the elderly and at-risk adults with the 23-valent pneumococcal polysaccharide vaccine or 13-valent pneumococcal conjugate vaccine in the UK

OBJECTIVE

The introduction of routine childhood vaccination with pneumococcal conjugate vaccines (PCVs) has led to a decrease in the overall incidence of pneumococcal disease in all ages and a change in the serotype distribution of the remaining disease. This study assessed the cost-effectiveness of vaccinating ≥65 years and at risk adults with either the 23-valent pneumococcal polysaccharide vaccine (PPV23) or the 13-valent conjugate vaccine (PCV13) in the UK, accounting for epidemiological changes.

METHODS

A population-based Markov model was used to track one UK-based cohort of individuals assuming PPV23, PCV13 or no vaccination until death.

RESULTS

The ICER was estimated at £8413 when PPV23 was compared to no vaccination. PPV23 dominated PCV13.

CONCLUSION

This model suggests that vaccinating with PPV23 is cost-effective when compared to both PCV13 and no vaccination. As PPV23 covers 80-90% in the UK of all serotypes causing invasive pneumococcal diseases, it remains cost-effective despite recent reductions in invasive pneumococcal diseases incidence in adults.

A public health and budget impact analysis of vaccinating the elderly and at-risk adults with the 23-valent pneumococcal polysaccharide vaccine or 13-valent pneumococcal conjugate vaccine in the UK

OBJECTIVE

Since the introduction of the routine childhood immunization, a change in epidemiology of pneumococcal disease has been seen in both children and adults. This study aimed to quantify the public health and budget impact of pneumococcal vaccination of the elderly and those in at risk groups in the UK.

METHODS

The model was adapted from a previous population-based Markov model. At-risk adults and the elderly were assumed to receive PPV23 or PCV13 vaccination or no vaccination.

RESULTS

Over the study period (2012-2016), PPV23 vaccination led to a reduction in the number of invasive pneumococcal disease cases in most scenarios. The net budget impact ranged between £15 and £39 million (vs no vaccination) or between -£116 and -£93 million (vs PCV13).

CONCLUSION

PPV23 vaccination program remains the optimal strategy from public health and budgetary perspectives despite epidemiological changes. PCV13 is likely to impose a significant budget with limited health benefits.

The CAPITA study of protein-conjugate pneumococcal vaccine and its implications for use in adults in developed countries

Until 1990, Hemophilus influenzae type b (HITB) was a major cause of morbidity and mortality in toddlers and young children. A vaccine consisting of purified polyribosyl ribitol phosphate (PRP), the capsular polysaccharide (CPS) of HITB, had been shown to be ineffective as an antigen in the population at risk, and this vaccine was withdrawn from the market within a few years of its introduction. By contrast, the discovery that PRP, when covalently bound to an antigenic protein, stimulated antibody production in infants and toddlers, (1) led to the development of a vaccine that has all but eradicated HITB infection and brought about a near-disappearance of this organism in the United States.

A randomized clinical trial of the immunogenicity of 7-valent pneumococcal conjugate vaccine compared to 23-valent polysaccharide vaccine in frail, hospitalized elderly

BACKGROUND

Elderly people do not mount strong immune responses to vaccines. We compared 23-valent capsular polysaccharide (23vPPV) alone versus 7-valent conjugate (PCV7) vaccine followed by 23vPPV 6 months later in hospitalized elderly.

METHODS

Participants were randomized to receive 23vPPV or PCV7-23vPPV. Antibodies against serotypes 3, 4, 6A, 6B, 9V, 14, 18C, 19A, 19F, 23F were measured by enzyme-linked immunosorbent (ELISA) and opsonophagocytic (OPA) assays at baseline, 6 months and 12 months.

RESULTS

Of 312 recruited, between 40% and 72% of subjects had undetectable OPA titres at baseline. After one dose, PCV7 recipients had significantly higher responses to serotypes 9V (both assays) and 23F (OPA only), and 23vPPV recipients had significantly higher responses to serotype 3 (ELISA), 19F and 19A (OPA only). In subjects with undetectable OPA titres at baseline, a proportionately greater rise in OPA titre (P<0.01) was seen for all serotypes after both vaccines. The GMT ratio of OPA was significantly higher at 12 months in the PCV7-23vPPV group for serotypes 6A, 9V, 18C and 23F. OPA titre levels for these serotypes increased moderately after 6 months, whereas immunity waned in the 23vPPV only arm.

CONCLUSION

We did not show overwhelming benefit of one vaccine over the other. Low baseline immunity does not preclude a robust immune response, reiterating the importance of vaccinating the frail elderly. A schedule of PCV7-23vPPV prevents waning of antibody, suggesting that both vaccines could be useful in the elderly. Follow up studies are needed to determine persistence of immunity.

TRIAL REGISTRATION

The Australian Clinical Trials Registry ACTRN12607000387426.

The management of community-acquired pneumonia in the elderly

Pneumonia is one of the main causes of morbidity and mortality in the elderly. The elderly population has exponentially increased in the last decades and the current epidemiological trends indicate that it is expected to further increase. Therefore, recognizing the special needs of older people is of paramount importance. In this review we address the main differences between elderly and adult patients with pneumonia. We focus on several aspects, including the atypical clinical presentation of pneumonia in the elderly, the methods to assess severity of illness, the appropriate setting of care, and the management of comorbidities. We also discuss how to approach the common complications of severe pneumonia, including acute respiratory failure and severe sepsis. Moreover, we debate whether or not elderly patients are at higher risk of infection due to multi-drug resistant pathogens and which risk factors should be considered when choosing the antibiotic therapy. We highlight the differences in the definition of clinical stability and treatment failure between adults and elderly patients. Finally, we review the main outcomes, preventive and supportive measures to be considered in elderly patients with pneumonia.

Preventing pneumococcal disease in the elderly: recent advances in vaccines and implications for clinical practice

Streptococcus pneumoniae remains a major cause of morbidity and mortality throughout the world. To date, after the introduction of routine childhood immunization, elderly people (i.e., persons aged 65 years or older) suffer the greatest burden of pneumococcal disease in developed countries. At present, two anti-pneumococcal vaccines are available for use in adults: the 23-valent pneumococcal polysaccharide vaccine (PPV23) and the 13-valent protein-polysaccharide conjugate vaccine (PCV13). This article reviews current data about the burden of pneumococcal disease in the elderly, as well as evidence for immunogenicity, clinical efficacy, and possible cost-effectiveness of both vaccines. The main advantage of PCV13 is that it may be more effective than PPV23, but a major limitation is that it is directed against strains that are likely to be greatly reduced in the population since its introduction in childhood immunization. The main disadvantage of PPV23 is that it may be less effective than PCV13 against vaccine-type infections but a major advantage is that it may provide protection against ten additional serotypes. To date, expert committees have not changed recommendations for pneumococcal vaccination in adults. However, at present, they are evaluating different alternatives (basically, maintaining PPV23, changing from PPV23 to PCV13 in some groups, or adding PCV13 for all or some target adult population subgroups). Critical data (clinical efficacy reported in ongoing trials and magnitude of indirect effects of pediatric PCV13 programs) needed to make a well-informed decision could be available during 2013. Considering all concerns over indirect effects and replacement strains following the use of polysaccharide-based vaccines, efforts should be directed toward developing vaccines, such as protein-based pneumococcal vaccines, with potential serotype-independent protection. Meanwhile, according to current recommendations, PPV23 should continue to be used for high-risk adults and all elderly people (with and without additional high-risk conditions). Although it is only moderately effective, it has a considerable serotype coverage and at-risk persons can benefit from the vaccination. High-risk individuals could also obtain a benefit from adding PCV13, but more data are needed before a universal recommendation can be made.

Immunosenescence and pneumococcal disease: an imbalance in host-pathogen interactions

Respiratory infections are among the most important causes of morbidity and mortality from infectious diseases worldwide. The most common causative bacterium, Streptococcus pneumoniae, frequently colonises the upper respiratory tract, where it resides mostly asymptomatically. Occasionally, however, S pneumoniae can cause severe disease such as pneumonia. Local host immunity is essential to control colonising pathogens by preventing overgrowth, spread, and invasion. However, age-related immune deficits in elderly people, known as immunosenescence, might contribute to increased disease burden. We review present knowledge about immunosenescence in the respiratory tract against Gram-positive bacteria, particularly S pneumoniae. We discuss the possible underdetection of pneumococcal colonisation in elderly people, and suggest changes to present surveillance methods to improve understanding of the relation between colonisation and disease. We conclude that present knowledge about alteration of host-pathogen interactions by immunosenescence in the respiratory tract is insufficient, and that research is needed to enable improved measures for prevention.

The majority of adult pneumococcal invasive infections in Portugal are still potentially vaccine preventable in spite of significant declines of serotypes 1 and 5

In Portugal, pneumococcal conjugate vaccines have been administered to children outside of the national immunization plan since 2001. We determined the serotype and antimicrobial susceptibility of 1265 isolates responsible for adult invasive pneumococcal infections (IPD) between 2009 and 2011 and compared the results with previously published data from 1999 to 2008. Serotypes 3 (12.6%), 7F (10.0%), 19A (9.1%), 14 (8.4%), 1 (6.9%) and 8 (6.2%) were the most frequent and together accounted for 53.2% of adult IPD. Serotypes 1 and 5 declined significantly while serotype 34, not included in any vaccine, increased. Taken together, the serotypes included in the 13-valent conjugate vaccine (PCV13) peaked among adult IPD isolates in 2008 (70.2%) and declined since then reaching 53.5% in 2011. The decline in the serotypes included in the 23-valent polysaccharide vaccine since 2007 was also significant but much more modest with 79.2% of the isolates causing IPD in 2011 expressing these serotypes. Since the changes in serotypes causing IPD in adults coincided with the 10-valent and PCV13 introduction in children, it is unlikely that vaccination triggered these changes although it may have accelerated them. The proportion of IPD caused by serotypes included in the 7-valent conjugate vaccine remained stable (19.0%). Both penicillin non-susceptibility and erythromycin resistance increased in the study period, with serotypes 14 and 19A accounting for the majority of resistant isolates.

Pneumococcal conjugate vaccination for older adults: Reply letter to Hollingsworth et al

Hollingsworth and Isturiz (1) have raised several questions about our earlier review of the use of pneumococcal conjugate (PCV) or polysaccharide (PPV) vaccine for older adults (i.e., ≥65 y of age). (2) They begin by citing two metaanalyses published in 2009 and 2013 that concluded that prevention of pneumococcal pneumonia could not be demonstrated for PPV. (3)(,) (4) They overlook my earlier review of five metaanalyses that was published in 2004. (5) This review showed that the study populations in prospective trials of PPV were often not representative of the populations of elderly and high-risk adults for whom PPV is recommended. Furthermore, the five metaanalyses often omitted clinical trials that should have been evaluated, included trials that should have been omitted, and frequently miscounted the numbers of subjects and outcome events in the individual clinical trials. More important, retrospective sample size calculations showed that none of the five metaanalyses included an adequate number of person years of observation to rule out false-negative results. The numbers speak for themselves and cannot be ignored. Simply put, metaanalyses of the PPV clinical trials will never tell us whether the vaccine prevents pneumococcal pneumonia or all-cause pneumonia in elderly and high-risk adults, and consequently they must be regarded as inconclusive and uninformative. Since 2004, only one small prospective clinical trial of PPV has been published (reviewed in 6). Nothing new has been added to our knowledge of PPV efficacy by the more recent metaanalyses. (3)(,) (4) Epidemiologists have reminded us that the lack of evidence of PPV efficacy is not evidence of its absence. The conclusions of our earlier review still stand. (5.)

Aging promotes B-1b cell responses to native, but not protein-conjugated, pneumococcal polysaccharides: implications for vaccine protection in older adults

The efficacy of different vaccines in protecting elderly individuals against Streptococcus pneumoniae infections is not clear. In the current study, aged mice (22-25 months old) exhibited significantly increased susceptibility to respiratory infection with serotype 3 S. pneumoniae relative to younger adult mice, regardless of whether mice were naive or immunized with native pneumococcal polysaccharide (PPS; Pneumovax23) or protein-PPS conjugate (Prevnar-13) vaccines. Nonetheless, Pneumovax-immunized aged mice developed limited bacteremia following respiratory challenge and exhibited significantly increased survival following systemic challenge relative to Prevnar-immune aged mice and young mice that had received either vaccine. This was explained by >10-fold increases in PPS-specific immunoglobulin G (IgG) levels in Pneumovax-immunized aged mice relative to other groups. Remarkably, PPS3-specific B-cell expansion, IgG switching, plasmablast differentiation, and spleen and bone marrow antibody-secreting cell frequencies were 10-fold higher in aged mice following Pneumovax immunization relative to young mice, due to significantly increased B-1b cell participation. In summary, this study highlights (1) the need to devise strategies to enhance respiratory immunity in aged populations, (2) the diverse responses young and aged populations generate to Pneumovax vs Prevnar vaccines, and (3) the potential value of exploiting B-1b cell responses in aged individuals for increased vaccine efficacy.

How effective is vaccination in preventing pneumococcal disease?

Vaccination with a preparation that currently contains 23 pneumococcal capsular polysaccharides (PPV23) successfully reduces the risk of serious pneumococcal infection by an estimated 50% to 80%. Because infants and young children do not respond to polysaccharide antigens, a conjugated polysaccharide vaccine that first contained 7 capsule types (PCV7) and now contains 13 capsule types (PCV13) was developed for use in them. A single study in patients with AIDS showed protection against pneumococcal disease by PCV13, but not after PPV23. Based on these observations, the CDC has now recommended that immunocompromized adults receive PCV13 followed 8 weeks later by PPV23.

Pneumococcal vaccination of older adults: conjugate or polysaccharide?

Invasive pneumococcal disease continues to be important problem for older adults. Pneumococcal polysaccharide vaccine (PPV23) has a clinical effectiveness of 43-81%, and following primary vaccination and revaccination, antibody responses last 5-10 y. Hyporesponsiveness to a second dose of vaccine has not been shown to be a significant problem. The use of pneumococcal conjugate vaccines (initially PCV7; more recently PCV13) has led to a dramatic fall in the incidence of conjugate vaccine-type invasive pneumococcal disease in children. Because PCVs are immunogenic in older adults, the question has arisen as to whether to also use PCVs in this age group. However, PCV vaccination of children has also reduced the incidence of conjugate vaccine-serotype disease in older adults, and so wherever PCVs are used in children, there is no epidemiological reason to vaccinate older adults with PCV. The cost-effectiveness of PPV for older adults has changed wherever PCVs have been used for children, and this needs to be periodically re-evaluated.

Serologic response to primary vaccination with 7-valent pneumococcal conjugate vaccine is better than with 23-valent pneumococcal polysaccharide vaccine in HIV-infected patients in the era of combination antiretroviral therapy

OBJECTIVES

The objectives of this study were to compare the serologic responses at week 48 to primary vaccination with 23-valent pneumococcal polysaccharide vaccine (PPV) vs. 7-valent pneumococcal conjugate vaccine (PCV); and to identify factors associated with serologic response in HIV-infected adult patients with access to combination antiretroviral therapy (cART).

METHODS

One hundred and four CD4-matched pairs of HIV-infected patients who underwent primary pneumococcal vaccination with 23-valent PPV or 7-valent PCV were enrolled for determinations of anti-capsular antibody responses against four serotypes (6B, 14, 19F and 23F) at baseline, 24 weeks and 48 weeks following vaccination. Significant antibody responses were defined as 2-fold or greater increase of antibody levels at week 48 compared with baseline. The logistic regression model was used to determine the factors associated with serologic response to at least one and two serotypes.

RESULTS

At week 48, patients who received PCV demonstrated a statistically significantly higher response rate to at least 2 serotypes than those who received PPV (37.5% vs. 20.2%, p = 0.006). In multivariate analysis, factors associated with significant antibody responses to at least one or two serotypes included receipt of PCV (adjusted odds ratio [AOR], 2.42 [95% CI, 1.23-4.78] and 3.58 [95% CI. 1.76-7.28], respectively), and undetectable plasma HIV RNA load (< 400 copies/ml) at vaccination (AOR, 1.47 [95% CI, 0.60-3.64] and 3.62 [95% CI, 1.11-11.81], respectively).

CONCLUSIONS

Primary vaccination with 7-valent PCV achieved a significantly better serologic responses to one or two out of the four serotypes studied at week 48 than with 23-valent PPV in HIV-infected patients in the cART era. Suppression of HIV replication when primary vaccination was administered was associated with better serologic responses.

Vaccination of risk groups in England using the 13 valent pneumococcal conjugate vaccine: economic analysis

OBJECTIVE

To estimate the cost effectiveness of vaccinating people with high risk conditions against invasive pneumococcal disease using the 13 valent pneumococcal conjugate vaccine.

DESIGN

Economic evaluation using a cohort model from the perspective of healthcare providers.

SETTING

England.

PARTICIPANTS

People aged 2 years and older at increased risk of invasive pneumococcal disease due to chronic kidney disease; splenic dysfunction; HIV infection; a compromised immune system; chronic heart, liver, or respiratory disease; or diabetes.

MAIN OUTCOME MEASURES

Costs, gains in life years and quality adjusted life years (QALYs), and incremental cost effectiveness ratios.

RESULTS

Increasing indirect protection resulting from the vaccination programme of infants using the 13 valent pneumococcal conjugate vaccine means that the burden of disease preventable by targeting high risk groups will diminish in time. Under base case assumptions--that is, no overall impact on non bacteraemic pneumonia in high risk groups and assuming the high risk vaccination programme would be launched two to three years after the infant programme--the incremental cost effectiveness ratio was estimated to be more than £30,000 (€37,216; $48,210) per QALY gained for most risk groups. If, however, the vaccine does not offer protection against non-bacteraemic pneumococcal pneumonia or the vaccine was introduced concomitantly with the infant 13 valent pneumococcal conjugate vaccination programme then vaccinating high risk people would (more) likely be cost effective. Sensitivity analyses showed that the cost effectiveness was particularly sensitive to assumed herd benefits and vaccine efficacy estimates.

CONCLUSION

Under base case assumptions it is unlikely that a pneumococcal vaccination programme aimed at risk groups could be considered cost effective. Uncertainty could be substantially reduced by establishing the effectiveness of the 13 valent pneumococcal conjugate vaccine against non-bacteraemic pneumococcal pneumonia, particularly in at risk groups.

Long-term comparative immunogenicity of protein conjugate and free polysaccharide pneumococcal vaccines in chronic obstructive pulmonary disease

BACKGROUND

Although the 23-valent pneumococcal polysaccharide vaccine (PPSV23) protects against invasive disease in young healthy persons, randomized controlled trials in chronic obstructive pulmonary disease (COPD) have demonstrated no benefit in the intention-to-treat population. We previously reported that the 7-valent diphtheria-conjugated pneumococcal polysaccharide vaccine (PCV7) is safe and induced greater serotype-specific immunoglobulin G (IgG) and functional antibody than did PPSV23 1 month after vaccination. We hypothesized that these advantages would persist at 1 and 2 years.

METHODS

One hundred eighty-one patients with moderate to severe COPD were randomized to receive PPSV23 (n = 90) or PCV7 (1.0 mL; n = 91). We measured IgG by enzyme-linked immunosorbent assay and assessed functional antibody activity by a standardized opsonophagocytosis assay, reported as a killing index (OPK). We determined differences in IgG and OPK between vaccine groups at 1 and 2 years.

RESULTS

Relative to PPSV23, PCV7 induced greater OPK at both 1 and 2 years for 6 of 7 serotypes (not 19F). This response was statistically greater for 5 of 7 serotypes at 1 year and 4 of 7 at 2 years. Comparable differences in IgG were observed but were less often statistically significant. Despite meeting Centers for Disease Control and Prevention criteria for PPSV23 administration, almost 50% of individuals had never been vaccinated. No differences in the frequency of acute exacerbations, pneumonia, or hospitalization were observed.

CONCLUSIONS

PCV7 induces a greater functional antibody response than PPSV23 in patients with COPD that persists for 2 years after vaccination. This superior functional response supports testing of conjugate vaccination in studies examining clinical end points.

CLINICAL TRIALS REGISTRATION

NCT00457977.

Pneumococcal vaccination among adults with chronic respiratory diseases: a historical overview

Streptococcus pneumoniae, the most common cause of community-acquired pneumonia, remains a major cause of morbidity and mortality worldwide. The presence of chronic respiratory illness is a major risk factor for pneumonia, and smoking (the most common cause of chronic obstructive pulmonary disease) is also an important risk factor for pneumonia and invasive pneumococcal disease. There are currently three established approaches to antipneumococcal vaccination: capsular polysaccharide pneumococcal vaccines (recommended for adults and some children at risk), protein-polysaccharide conjugate pneumococcal vaccines (classically recommended for infants and young children and currently under evaluation for adults aged 50 years or older for the prevention of invasive disease) and experimental protein-based pneumococcal vaccines (under investigation in animal models). Although patients with chronic respiratory diseases are commonly described as an at-risk population for pneumococcal infections, studies on pneumococcal vaccination efficacy in such patients are very limited and vaccination effectiveness remains controversial. This paper reviews available data on the efficacy and effectiveness of polysaccharide pneumococcal vaccination among adults with chronic respiratory diseases.

Comparison of serologic responses to vaccination with one dose or two doses of 7-valent pneumococcal conjugate vaccine in HIV-infected adult patients

BACKGROUND

Vaccination with 7-valent pneumococcal conjugate vaccine (PCV) has been shown to decrease the incidence of recurrent invasive pneumococcal disease among HIV-infected adults in Africa. Longitudinal follow-up studies of serologic responses to different doses of 7-valent PCV are rarely performed in HIV-infected adult patients receiving combination antiretroviral therapy (cART).

METHODS

From October 2008 to June 2010, 115 CD4-matched pairs of HIV-infected patients aged ≥ 20 years who had no prior pneumococcal vaccination received one or two doses of 7-valent PCV. Anticapsular antibodies against 4 serotypes (6B, 14, 19F, and 23F) were examined at the 12th, 24th, 36th, and 48th week following vaccination. Significant antibody responses were defined as ≥ 2-fold increase in the IgG level plus a post-vaccination antibody level ≥ 1000 ng/ml.

RESULTS

The most common reported adverse effects were injection site soreness (19.3%) and pain (4.8%). Significant antibody response rate was highest for serotype 14, followed by 23F, 19F, and 6B in all of the four time points examined. At week 48, patients who received two doses of 7-valent PCV had a significantly higher response rate to serotype 6B (P=0.03) and 23F (P=0.01) than those who received one dose; moreover, the former group also had a higher response rate to at least one (P=0.03) and two serotypes (P=0.02) in intention-to-treat analysis than the latter group.

CONCLUSIONS

HIV-infected adult patients on cART who received two doses of 7-valent PCV achieved better serological responses to at least one serotype than those who received one dose during the 48 weeks of follow-up.

Safety, immunogenicity and efficacy of pneumococcal conjugate vaccine in HIV-infected individuals

Streptococcus pneumoniae is the leading bacterial opportunistic infection in HIV-infected individuals. Anti-retroviral treatment (ART) of HIV-infected individuals reduces their risk of invasive pneumococcal disease (IPD), however, it remains 20- to 40-fold greater compared with age-matched general population. This review summarizes the available published data on the immunogenicity, safety and efficacy of pneumococcal polysaccharide-protein conjugate vaccines (PCV) in HIV-infected children and adults.   Several studies have demonstrated that PCV are safe in the HIV-infected persons. Although PCV are immunogenic in HIV-infected infants, the antibodies produced are functionally impaired, there is possibly a lack or loss of anamnestic responses and immunity declines in later life However, quantitative and qualitative antibody responses to PCV in HIV-infected infants are enhanced when vaccination occurs whilst on ART, as well as if vaccination occurs when the CD4+ cell percentage is ≥ 25% and if the nadir CD4+ is > 15%. Although the efficacy of PCV was lower, the vaccine preventable burden of hospitalization for IPD and clinical pneumonia were 18-fold and 9-fold greater, respectively, in HIV-infected children compared with -uninfected children. In HIV-infected adults, PCV vaccination induces more durable and functional antibody responses in individuals on ART at the time of vaccination than in ART-naive adults, independently of baseline CD4+ cell count, although there does not appear to be much benefit from a second-dose of PCV. PCV has also been shown to reduce the risk of recurrent IPD by 74% in HIV-infected adults not on ART, albeit, also with subsequent decline in immunity and protection.