Experience with pneumococcal polysaccharide conjugate vaccine (conjugated to CRM197 carrier protein) in children and adults

CRM197-scaffolded vaccines designed by epitope grafting ameliorate cognitive decline in an Alzheimer's disease model

Alzheimer's disease (AD) is the leading cause of dementia in the elderly. Amyloid-beta (Aβ) plaque accumulation and tau neurofibrillary tangles (NFTs) formation in the brain are major neuropathological hallmarks of AD. Immunotherapies targeting Aβ and/or tau are deemed the most promising approaches for AD. Administrations with monoclonal antibodies against Aβ have yielded substantial breakthroughs clinically. Most vaccines tested clinically so far failed to prove efficacious in large part due to inappropriate design of vaccine antigens. In this study, a structure-guided approach was employed to design novel antigens targeting Aβ and/or tau by grafting multiple copies of Aβ and/or tau B-cell epitope peptide onto CRM197, which is the most widely used carrier protein in polysaccharide conjugate vaccines. The immunogenicity of the vaccines was evaluated in BALB/c mice and the efficacy was tested in a transgenic mouse model of human amyloidopathy. The antigens were highly immunogenic early vaccination substantially ameliorated cognitive decline in APP/PS1 mice and significantly reduced insoluble Aβ42/40 in the brains. These results demonstrate that the engineered antigens have protective effects on AD mice, offering a promising translatable strategy for the prevention and/or treatment of AD.

Pneumococcal and Influenza Vaccination Coverage in Patients with Heart Failure: A Systematic Review

Background/Objectives: As heart failure (HF) patients face increased vulnerability to respiratory infections, optimizing pneumococcal and influenza vaccination coverage becomes pivotal for mitigating additional health risks and reducing hospitalizations, morbidity, and mortality rates within this population. In this specific subpopulation of patients, vaccination coverage for pneumococcal and influenza holds heightened significance compared to other vaccines due to their susceptibility to respiratory infections, which can exacerbate existing cardiovascular conditions and lead to severe complications or even death. However, despite the recognized benefits, vaccination coverage among HF patients remains below expectations. The aim of the present systematic review was to assess the vaccination coverage for influenza and pneumococcus in HF patients from 2005 to 2023 and the vaccination's effects on survival and hospitalizations. Methods: The authors developed the protocol of the review in accordance with the PRISMA guidelines, and the search was performed in databases including PubMed and Scopus. After the initial search, 851 studies were found in PubMed Library and 1961 in Scopus (total of 2812 studies). Results: After the initial evaluation, 23 publications were finally included in the analysis. The total study population consisted of 6,093,497 participants. Regarding the influenza vaccine, vaccination coverage ranged from low rates of 2.5% to very high rates of 97%, while the respective pneumococcal vaccination coverage ranged from 20% to 84.6%. Most studies demonstrated a beneficial effect of vaccination on survival and hospitalizations. Conclusions: The present systematic review study showed a wide variety of vaccination coverage among patients with heart failure.

Development and qualification of an automated capillary Western method for the identification of polysaccharide serotypes in pneumococcal conjugate vaccine (PCV)

Streptococcus pneumoniae bacterial infection causes mortality in both adults and infants. To mitigate the impact of the disease, several Pneumococcal conjugate vaccines (PCVs) have been manufactured for the U.S. market, including the recent approval of the 15-valent PCV Vaxneuvance™ from MSD. These vaccines demonstrate high efficacy for both the adult and pediatric dose. These PCVs contain multiple unique serotypes in the final, formulated vaccine product, and identifying a specific polysaccharide, in the presence of other serotypes, is a critical quality attribute that must be demonstrated through analytical testing. Here we describe the development and qualification of an identity assay using an automated capillary western system, called Simple Western, implementing a multi-valent system suitability sample (SSS) to determine individual polysaccharide components. The assay was optimized through rigorous analytical development and was successfully qualified for use in the clinical release of the PCV.

Pneumococcal Vaccine for Adults Aged ≥19 Years: Recommendations of the Advisory Committee on Immunization Practices, United States, 2023

This report compiles and summarizes all published recommendations from CDC’s Advisory Committee on Immunization Practices (ACIP) for use of pneumococcal vaccines in adults aged ≥19 years in the United States. This report also includes updated and new clinical guidance for implementation from CDC

Before 2021, ACIP recommended 23-valent pneumococcal polysaccharide vaccine (PPSV23) alone (up to 2 doses), or both a single dose of 13-valent pneumococcal conjugate vaccine (PCV13) in combination with 1–3 doses of PPSV23 in series (PCV13 followed by PPSV23), for use in U.S. adults depending on age and underlying risk for pneumococcal disease. In 2021, two new pneumococcal conjugate vaccines (PCVs), a 15-valent and a 20-valent PCV (PCV15 and PCV20), were licensed for use in U.S. adults aged ≥18 years by the Food and Drug Administration

ACIP recommendations specify the use of either PCV20 alone or PCV15 in series with PPSV23 for all adults aged ≥65 years and for adults aged 19–64 years with certain underlying medical conditions or other risk factors who have not received a PCV or whose vaccination history is unknown. In addition, ACIP recommends use of either a single dose of PCV20 or ≥1 dose of PPSV23 for adults who have started their pneumococcal vaccine series with PCV13 but have not received all recommended PPSV23 doses. Shared clinical decision-making is recommended regarding use of a supplemental PCV20 dose for adults aged ≥65 years who have completed their recommended vaccine series with both PCV13 and PPSV23

Updated and new clinical guidance for implementation from CDC includes the recommendation for use of PCV15 or PCV20 for adults who have received PPSV23 but have not received any PCV dose. The report also includes clinical guidance for adults who have received 7-valent PCV (PCV7) only and adults who are hematopoietic stem cell transplant recipients

Understanding the Molecular Basis for Homodimer Formation of the Pneumococcal Endolysin Cpl-1

The rise of multi-drug-resistant bacteria that cannot be treated with traditional antibiotics has prompted the search for alternatives to combat bacterial infections. Endolysins, which are bacteriophage-derived peptidoglycan hydrolases, are attractive tools in this fight. Several studies have already demonstrated the efficacy of endolysins in targeting bacterial infections. Endolysins encoded by bacteriophages that infect Gram-positive bacteria typically possess an N-terminal catalytic domain and a C-terminal cell-wall binding domain (CWBD). In this study, we have uncovered the molecular mechanisms that underlie formation of a homodimer of Cpl-1, an endolysin that targets Streptococcus pneumoniae. Here, we use site-directed mutagenesis, analytical size exclusion chromatography, and analytical ultracentrifugation to disprove a previous suggestion that three residues at the N-terminus of the CWBD are involved in the formation of a Cpl-1 dimer in the presence of choline in solution. We conclusively show that the C-terminal tail region of Cpl-1 is involved in formation of the dimer. Alanine scanning mutagenesis generated various tail mutant constructs that allowed identification of key residues that mediate Cpl-1 dimer formation. Finally, our results allowed identification of a consensus sequence (FxxEPDGLIT) required for choline-dependent dimer formation─a sequence that occurs frequently in pneumococcal autolysins and endolysins. These findings shed light on the mechanisms of Cpl-1 and related enzymes and can be used to inform future engineering efforts for their therapeutic development against S. pneumoniae.

Assessment of Crosslinkers between Peptide Antigen and Carrier Protein for Fusion Peptide-Directed Vaccines against HIV-1

Conjugate-vaccine immunogens require three components: a carrier protein, an antigen, and a crosslinker, capable of coupling antigen to carrier protein, while preserving both T-cell responses from carrier protein and B-cell responses from antigen. We previously showed that the N-terminal eight residues of the HIV-1 fusion peptide (FP8) as an antigen could prime for broad cross-clade neutralizing responses, that recombinant heavy chain of tetanus toxin (rTTHC) as a carrier protein provided optimal responses, and that choice of crosslinker could impact both antigenicity and immunogenicity. Here, we delve more deeply into the impact of varying the linker between FP8 and rTTHC. In specific, we assessed the physical properties, the antigenicity, and the immunogenicity of conjugates for crosslinkers ranging in spacer-arm length from 1.5 to 95.2 Å, with varying hydrophobicity and crosslinking-functional groups. Conjugates coupled with different degrees of multimerization and peptide-to-rTTHC stoichiometry, but all were well recognized by HIV-fusion-peptide-directed antibodies VRC34.01, VRC34.05, PGT151, and ACS202 except for the conjugate with the longest linker (24-PEGylated SMCC; SM(PEG)24), which had lower affinity for ACS202, as did the conjugate with the shortest linker (succinimidyl iodoacetate; SIA), which also had the lowest peptide-to-rTTHC stoichiometry. Murine immunizations testing seven FP8-rTTHC conjugates elicited fusion-peptide-directed antibody responses, with SIA- and SM(PEG)24-linked conjugates eliciting lower responses than the other five conjugates. After boosting with prefusion-closed envelope trimers from strains BG505 clade A and consensus clade C, trimer-directed antibody-binding responses were lower for the SIA-linked conjugate; elicited neutralizing responses were similar, however, though statistically lower for the SM(PEG)24-linked conjugate, when tested against a strain especially sensitive to fusion-peptide-directed responses. Overall, correlation analyses revealed the immunogenicity of FP8-rTTHC conjugates to be negatively impacted by hydrophilicity and extremes of length or low peptide-carrier stoichiometry, but robust to other linker parameters, with several commonly used crosslinkers yielding statistically indistinguishable serological results.

Conjugation of a Toll-Like Receptor Agonist to Glycans of an HIV Native-Like Envelope Trimer Preserves Neutralization Epitopes

Small molecule adjuvants are attractive for enhancing broad protection and durability of immune responses elicited by subunit vaccines. Covalent attachment of an adjuvant to an immunogen is particularly attractive because it simultaneously delivers both entities to antigen presenting cells resulting in more efficient immune activation. There is, however, a lack of methods to conjugate small molecule immune potentiators to viral glycoprotein immunogens without compromising epitope integrity. We describe herein a one-step enzymatic conjugation approach for the covalent attachment of small molecule adjuvants to N-linked glycans of viral glycoproteins. It involves the attachment of an immune potentiator to CMP-Neu5AcN3 by Cu(I)-catalyzed azide-alkyne 1,3-cycloaddition followed by sialyltransferase-mediated transfer to N-glycans of a viral glycoprotein. The method was employed to modify a native-like HIV envelope trimer with a Toll-like receptor 7/8 agonist. The modification did not compromise Env-trimer recognition by several broadly neutralization antibodies. Electron microscopy confirmed structural integrity of the modified immunogen.

Altmışbeş Yaş ve Üzeri Erişkinlerde Pnömokok Bağışıklaması ve Ülkemizdeki Pnömokok Aşı Uygulamaları

Sorunu ortaya çıkmadan önlemek şüphesiz tedaviye göre kolay ve ucuz bir yöntemdir. Birinci basamak sağlık hizmetlerinin esasını oluşturan koruyucu sağlık hizmetlerinden aşılama, aşı ile önlenebilir hastalıkların önlenmesi ve bu hastalıklara bağlı kayıpların azaltılabilmesi için olmazsa olmazdır. Yaşlılarda ve yüksek riskli erişkinlerde önemli morbidite ve mortaliteye sebep olan pnömokok infeksiyonlarına karşı ülkemizde uygulanan iki tip aşı vardır: konjuge pnömokok aşısı ve polisakkarid pnömokok aşısı. Erişkinlerde pnömokok aşılarının yararı kanıtlanmış olmasına rağmen aşı uygulanma oranları hedeflenen düzeyde olmadığı için iyileştirme çalışmalarına ihtiyaç vardır. Birinci basamak çalışanları başta olmak üzere aşı uygulayıcılarının eğitilmesi ve farkındalığının artırılması, topluma aşıların yararları ve olası riskleri hakkında yeterli bilgi verilmesi, sağlık kontrollerinin ve kayıtların düzenli olması, aşıların yeterli miktarda ve ücretsiz olarak sağlanması gerekmektedir. Bu derleme erişkinlerde pnömokok aşı uygulamalarında mevcut durumu gözden geçirmek ve aşılama oranlarını arttırmak için yapılması gereken uygulamaları vurgulamak amacıyla yazılmıştır.

Site-Specific Conjugation of Cell Wall Polyrhamnose to Protein SpyAD Envisioning a Safe Universal Group A Streptococcal Vaccine

Development of an effective vaccine against the leading human bacterial pathogen group A Streptococcus (GAS) is a public health priority. The species defining group A cell wall carbohydrate (GAC, Lancefield antigen) can be engineered to remove its immunodominant N-acetylglucosamine (GlcNAc) side chain, implicated in provoking autoimmune cross-reactivity in rheumatic heart disease, leaving its polyrhamnose core (GACPR). Here we generate a novel protein conjugate of the GACPR and test the utility of this conjugate antigen in active immunization. Instead of conjugation to a standard carrier protein, we selected SpyAD, a highly conserved GAS surface protein containing both B-cell and T-cell epitopes relevant to the bacterium that itself shows promise as a vaccine antigen. SpyAD was synthesized using the XpressTM cell-free protein expression system, incorporating a non-natural amino acid to which GACPR was conjugated by site-specific click chemistry to yield high molecular mass SpyAD-GACPR conjugates and avoid disruption of important T-cell and B-cell immunological epitopes. The conjugated SpyAD-GACPR elicited antibodies that bound the surface of multiple GAS strains of diverse M types and promoted opsonophagocytic killing by human neutrophils. Active immunization of mice with a multivalent vaccine consisting of SpyAD-GACPR, together with candidate vaccine antigens streptolysin O and C5a peptidase, protected against GAS challenge in a systemic infection model and localized skin infection model, without evidence of cross reactivity to human heart or brain tissue epitopes. This general approach may allow GAC to be safely and effectively included in future GAS subunit vaccine formulations with the goal of broad protection without autoreactivity.

Elicitation of integrated immunity in mice by a novel pneumococcal polysaccharide vaccine conjugated with HBV surface antigen

The conjugation of polysaccharides with an effective carrier protein is critical for the development of effective bacterial polysaccharide vaccines. Therefore, the identification and optimization of carrier proteins to induce an effective immune response is necessary for developing a combined vaccine. In the current study, we utilized hepatitis B virus surface antigen (HBsAg) as a novel carrier protein combined with a capsular polysaccharide molecule to develop a new pneumococcal conjugated vaccine. The specific antibodies and T cell immune response against the capsular polysaccharide and HBsAg in the mice immunized with this conjugated vaccine were evaluated. In addition, the unique gene profiles of immune cells induced by this conjugated vaccine in the immunized mice were analyzed. Our results demonstrated that the vaccine consisting of pneumonia type 33 F capsular polysaccharide (Pn33Fps) conjugated with HBsAg can induce strong specific immune responses against both antigens in vivo in immunized mice. Furthermore, the conjugated vaccine induced higher expression of genes related to the activation of immunity and higher antibody titers against Pn33Fps and HBsAg in mice than those obtained via vaccination with a single antigen. Analyses of the dynamic expression changes in immunity-related genes in mice immunized with Pn33Fps_HBs, Pn33Fps, or HBsAg indicated the potent immunogenicity of the conjugated vaccine. In addition, a pathological evaluation of the organs from immunized mice further suggested that the conjugated vaccine is safe. Together, these results indicate that a conjugated vaccine consisting of Pn33Fps with HBsAg is a novel and effective vaccine.

Carbohydrates in Vaccine Development

Despite advances in the development of new vaccines, there are still some diseases with no vaccine solutions. Therefore, further efforts are required to more comprehensively discern the different antigenic components of these microorganisms on a molecular level. This review summarizes advancement in the development of new carbohydrate-based vaccines. Following traditional vaccine counterparts, the carbohydrate-based vaccines introduced a new approach in fighting infectious diseases. Carbohydrates have played various roles in the development of carbohydrate-based vaccines, which are described in this review, including carbohydrates acting as antigens, carriers or targeting moieties. Carbohydrate-based vaccines against infectious diseases, such as group A streptococcus, meningococcal meningitis and human immunodeficiency virus, are also discussed. A number of carbohydrate- based vaccines, such as Pneumovax 23, Menveo and Pentacel, have been successfully marketed in the past few years and there is a promising standpoint for many more to come in the near future.

Immunogenicity and Optimal Timing of 13-Valent Pneumococcal Conjugate Vaccination during Adjuvant Chemotherapy in Gastric and Colorectal Cancer: A Randomized Controlled Trial

Purpose

Pneumococcal vaccination (13-valent pneumococcal conjugate vaccine [PCV13]) is recommended to cancer patients undergoing systemic chemotherapy. However, the optimal time interval between vaccine administration and initiation of chemotherapy has been little studied in adult patients with solid malignancies.

Materials and Methods

We conducted a prospective randomized controlled trial to evaluate whether administering PCV13 on the first day of chemotherapy is non-inferior to vaccinating 2 weeks prior to chemotherapy initiation. Patients were randomly assigned to two study arms, and serum samples were collected at baseline and 4 weeks after vaccination to analyze the serologic response against Streptococcus pneumoniae using a multiplexed opsonophagocytic killingassay.

Results

Of the 92 patients who underwent randomization, 43 patients in arm A (vaccination 2 weeks before chemotherapy) and 44 patients in arm B (vaccination on the first day of chemotherapy) were analyzed. Immunogenicity was assessed by geometric mean and fold-increase of post-vaccination titers, seroprotection rates (percentage of patients with post-vaccination titers > 1:64), and seroconversion rates (percentage of patients with > 4-fold increase in post-vaccination titers). Serologic responses to PCV13 did not differ significantly between the two study arms according to all three types of assessments.

Conclusion

The overall antibody response to PCV13 is adequate in patients with gastric and colorectal cancer during adjuvant chemotherapy, and no significant difference was found when patients were vaccinated two weeks before or on the day of chemotherapy initiation.

Development of experimental pneumococcal vaccine for mucosal immunization

Streptococcus pneumonia is an important human pathogen that causes various severe diseases such as pneumonia, otitis and meningitis. Vaccination against S. pneumoniae is implemented in many developed countries. The presently used vaccines are safe, well tolerated but relatively expensive and require modification due to the immunological changes of the epidemic strains. This paper describes the development of a new pneumococcal vaccine candidate for immunization on mucosal surfaces. For this purpose the antigens of chimeric protein PSPF, previously suggested for an injectable S. pneumoniae vaccine, were expressed on the surface of the live probiotic strain Enterococcus faecium L3. Experiments on laboratory mice vaccinated with live bacteria demonstrated the appearance of the specific IgA and IgG which provide protection against the lethal S. pneumoniae infection.

Limited impact of pneumococcal vaccines on invasive pneumococcal disease in Nunavik (Quebec)

OBJECTIVE

In 2002, a mass immunization campaign using the 23-valent pneumococcal polysaccharide vaccine (PPV23) was carried out in Nunavik to control an outbreak caused by a virulent clone of serotype 1 Streptococcus pneumoniae. At the same time, the 7-valent pneumococcal conjugate vaccine (PCV7) was introduced for routine immunization of infants, replaced by the 10-valent vaccine (PCV10) in 2009, and the 13-valent vaccine (PCV13) in 2011. The objective of this study was to describe the epidemiology of invasive pneumococcal disease (IPD) in relation to pneumococcal vaccine use.

METHOD

Retrospective analysis of IPD cases identified by the Quebec Public Health Laboratory during the period 1997-2016.

RESULTS

One hundred thirty-two IPD cases were identified during the study period. In adults, serotype 1 incidence decreased following the 2002 PPV23 mass campaign, but breakthrough cases occurred. Following PCV use, the incidence of vaccine-type IPD decreased markedly in children and also in adults but serotypes not covered by conjugate vaccines increased. The overall IPD rate was 43/100,000 person-years in the 1997-1999 pre-vaccine era and 58/100,000 person-years in 2010-2016.

CONCLUSIONS

The 2002 PPV23 mass immunization campaign may have contributed to control the serotype 1 outbreaks in Nunavik, but its effect was short-lived as IPDs caused by serotypes included in this vaccine continued to occur after 2005. PCV use in children induced important modifications in the epidemiology of IPD, but most of the benefits were eroded by serotype replacement.

[Risk of pneumococcal disease in elderly patients with and without previous vaccination]

Objetivos

Conocer la cobertura vacunal antineumocócica en pacientes ≥ 65 años, así como el riesgo de enfermedad neumocócica según hayan o no recibido dicha vacunación.

Diseño

Estudio transversal, seguido de cohorte histórica.

Emplazamiento

Ámbito urbano.

Participantes

Se seleccionaron por muestreo sistemático 2.805 personas ≥ 65 años de la ciudad de Albacete.

Mediciones principales

Variable dependiente: diagnóstico de enfermedad neumocócica y fecha. Variables independientes: edad, sexo, enfermedades crónicas, medicación, vacunación antineumocócica y fecha. Se revisaron las historias clínicas informatizadas, de 1-1-2009 a octubre-diciembre de 2015. Se ha realizado un análisis descriptivo, se ha calculado el riesgo relativo de aparición de enfermedad neumocócica según la vacunación y se ha realizado un análisis de supervivencia con el programa estadístico SPSS 17.0.

Resultados

La mediana de edad era de 71 años; el 57,2% eran mujeres. Recibieron vacuna polisacárida el 46,0% (IC 95% 44,1-47,8). Solo 10 recibieron la conjugada. Fueron diagnosticadas de enfermedad neumocócica invasiva 22 personas, y de no invasiva, 153. El riesgo relativo de enfermedad neumocócica en vacunados frente a no vacunados, respectivamente para invasiva y no invasiva, era 1,59 (IC 95% 0,69-3,68) y 1,84 (IC 95% 1,33-2,54). Por regresión de Cox se demostró un mayor riesgo de enfermedad no invasiva para EPOC (1,95; IC 95% 1,32-2,89), tabaquismo (1,87; IC 95% 1,28-2,73), corticoterapia (1,73; IC 95% 1,08-2,79), vacunación polisacárida (141,41; IC 95% 5,92-3.378,49) y edad (1,11; IC 95% 1,08-1,14), con interacción entre estas 2 (0,94; IC 95% 0,91-0,98).

Conclusiones

Existe un mayor riesgo de presentar enfermedad neumocócica en pacientes ≥ 65 años vacunados con la polisacárida, si bien habría que considerar un efecto protector en los vacunados de mayor edad.

The development of a staphylococcus aureus four antigen vaccine for use prior to elective orthopedic surgery

Staphylococcus aureus (S. aureus) is a challenging bacterial pathogen which can cause a range of diseases, from mild skin infections, to more serious and invasive disease including deep or organ space surgical site infections, life-threatening bacteremia, and sepsis. S. aureus rapidly develops resistance to antibiotic treatments. Despite current infection control measures, the burden of disease remains high. The most advanced vaccine in clinical development is a 4 antigen S. aureus vaccine (SA4Ag) candidate that is being evaluated in a phase 2b/3 efficacy study in patients undergoing elective spinal fusion surgery (STaphylococcus aureus suRgical Inpatient Vaccine Efficacy [STRIVE]). SA4Ag has been shown in early phase clinical trials to be generally safe and well tolerated, and to induce high levels of bactericidal antibodies in healthy adults. In this review we discuss the design of SA4Ag, as well as the proposed clinical development plan supporting licensure of SA4Ag for the prevention of invasive disease caused by S. aureus in elective orthopedic surgical populations. We also explore the rationale for the generalizability of the results of the STRIVE efficacy study (patients undergoing elective open posterior multilevel instrumented spinal fusion surgery) to a broad elective orthopedic surgery population due to the common pathophysiology of invasive S. aureus disease and commonalties of patient and procedural risk factors for developing postoperative S. aureus surgical site infections.

T cells control the generation of nanomolar-affinity anti-glycan antibodies

Vaccines targeting glycan structures at the surface of pathogenic microbes must overcome the inherent T cell-independent nature of immune responses against glycans. Carbohydrate conjugate vaccines achieve this by coupling bacterial polysaccharides to a carrier protein that recruits heterologous CD4 T cells to help B cell maturation. Yet they most often produce low- to medium-affinity immune responses of limited duration in immunologically fit individuals and disappointing results in the elderly and immunocompromised patients. Here, we hypothesized that these limitations result from suboptimal T cell help. To produce the next generation of more efficacious conjugate vaccines, we have explored a synthetic design aimed at focusing both B cell and T cell recognition to a single short glycan displayed at the surface of a virus-like particle. We tested and established the proof of concept of this approach for 2 serotypes of Streptococcus pneumoniae. In both cases, these vaccines elicited serotype-specific, protective, and long-lasting IgG antibodies of nanomolar affinity against the target glycans in mice. We further identified a requirement for CD4 T cells in the anti-glycan antibody response. Our findings establish the design principles for improved glycan conjugate vaccines. We surmise that the same approach can be used for any microbial glycan of interest.

Changing trends in serotypes of S. pneumoniae isolates causing invasive and non-invasive diseases in unvaccinated population in Mexico (2000-2014)

OBJECTIVE

Introduction of pneumococcal conjugate vaccines (PCV) targeted against a limited number of serotypes substantially decreased invasive (IPD) and non-invasive pneumococcal diseases (NIPD) but it was accompanied by non-vaccine type replacement disease. After 9 years of introduction of PCV in Mexico, we analyze the evidence of the indirect effects on IPD and NIPD serotype distribution among groups not targeted to receive the vaccine.

METHODS

From January 2000 to December 2014, pneumococcal strains isolated from IPD and NIPD cases from patients ≥5 years of age from participant hospitals of the SIREVA II (Sistema Regional de Vacunas) network were serotyped. A regression analysis was performed considering year and proportion of serotypes included in the different vaccine formulations (PCV7, PCV10 and PCV13). The slope was obtained for each regression line and their correspondent p-value. The proportion of each serotype in the pre-PCV7 and post-PCV7 periods was evaluated by χ2 test.

RESULTS

From a total of 1147 pneumococcal strains recovered, 570 corresponded to the pre-PCV7 and 577 to the post-PCV7 periods. The proportion of vaccine serotypes included in the three PCV formulations decreased by 2.4, 2.6 and 1.3%, respectively per year during the study period. A significant increase of serotype 19A was observed in the post-vaccine period in all age groups.

CONCLUSIONS

A percentage of annual decline of serotypes causing IPD and NIPD included in PCV was detected among groups not targeted to receive the vaccine, probably due to herd effect. Considering pneumococcal serotype distribution is a dynamic process, we highlight the importance of surveillance programs.

Hospitalizations for pneumonia, invasive diseases and otitis in Tuscany (Italy), 2002-2014: Which was the impact of universal pneumococcal pediatric vaccination?

Streptococcus pneumoniae is the main causative organism of acute media otitis in children and meningitis and bacterial pneumonia in the community. Since 2008 in Tuscany, central Italy, the pneumococcal conjugate vaccine (7-valent vaccine, switched to 13-valent vaccine in 2010) was actively offered free of charge to all newborns. Aim of the study is to evaluate the impact of pneumococcal pediatric vaccination in the Tuscan population on hospitalizations potentially caused by S. pneumoniae, during pre-vaccination (PVP, 2002–2007) and vaccination period (VP, 2009–2014). We analyzed hospital discharge records (HDRs) of all hospitals in Tuscany from 2002 to 2014. Hospitalizations potentially due to pneumococcal diseases were 347, 221. The general hospitalization rate was 716/100,000 inhabitants during PVP and 753/100,000 in VP, with a decrease of 29.1% in the age-group 0–9 y (“target” of the vaccination program) and an increase of 75.7% in subjects >64 y of age. During VP, admission days and hospitalization costs increased (6.2% and 24.2%, respectively), especially in patients >64 y (12.9% and 33.8%, respectively); in children <10 y decreased by 21.2% and 12.8%, respectively. The pneumococcal pediatric vaccination resulted in the decrease of hospitalizations in younger but the expected indirect effect in the elderly was not reported, justifying the Tuscan recommendation to extend the vaccination to subjects > 64 y.

Strategies to develop vaccines of pediatric interest

INTRODUCTION

The success of the vaccines available on the market has significantly increased interest in vaccine development. Areas covered: The main aim of this paper is to discuss the most important vaccines of pediatric interest that are currently being developed. New pneumococcal vaccines and vaccines against group B Streptococcus, Staphylococcus aureus and respiratory syncytial virus are analyzed in detail. Expert commentary: Advances in understanding human immunology, including human monoclonal antibody identification, sequencing technology, and the ability to solve atomic level structures of vaccine targets have provided tools to guide the rational design of future vaccines. It is likely that some of these vaccines will reach the market in the future and will thus partially contribute to the prevention of very severe diseases that significantly affect the morbidity and mortality of children. However, further studies in animals and several clinical trials in children must be performed before new vaccines become licensed.

Parental knowledge, attitudes and perception of pneumococcal disease and pneumococcal conjugate vaccines in Singapore: a questionnaire-based assessment

Background

Under the National Childhood Immunisation Schedule (NCIS) in Singapore most vaccines are provided free while some, including pneumococcal conjugate vaccines (PCV), added to the NCIS in October 2009, are not free. In contrast to ≥95 % coverage achieved for recommended childhood vaccines that are free, 2013 coverage of the PCV booster dose was 58.9 % (for unclear reasons). To date, no population impact on pneumococcal disease (PD) has been observed. We conducted a questionnaire-based study of parents of young children to assess the value of PCV to parents, and to quantify the extent to which vaccine cost is a barrier to PCV uptake in Singapore.

Methods

A single, trained interviewer administered a questionnaire to 200 parents ≥21 years of age with young children attending the Singapore Sengkang Polyclinic. The questionnaire asked closed-ended questions on parents’ knowledge about PD and PCV. A 5-point Likert scale measured perceived benefits and barriers to PCV vaccination.

Results

There were 162 parents whose children were either PCV-vaccinated or who intended to vaccinate their child with PCV (Vaccinated group), and 38 whose children were non-PCV vaccinated or who did not intend to vaccinate (Unvaccinated group). The odds ratio for PCV vaccination among parents who perceived cost as a barrier was 0.16 (95%CI 0.02–1.23). Compared to the Vaccinated group, parents in the Unvaccinated group were less willing to pay for PCV (50.0 %/94.4 %). Compared to the Vaccinated group, fewer parents in the Unvaccinated group had heard about PD (34.2 %/82.1 %) or PCV (36.8 %/69.1 %), or perceived that PD was a threat to their child. Fewer parents in the Unvaccinated group knew that vaccination could prevent PD (28.9 %/77.8 %), or reported that PCV vaccination was recommended to them by any source (63.2 % had no PCV recommendation, versus 20.4 %). When informed that PCV is included in the NCIS only 65.8 % of parents in the Unvaccinated group, versus 98.8 % in the Vaccinated group, indicated that they would be willing to vaccinate their child.

Conclusions

Cost considerations, not having vaccination recommended to parents and a lack of knowledge among parents of the benefits of PCV to the child may adversely impact PCV uptake in Singapore.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-016-3597-5) contains supplementary material, which is available to authorized users.

Reduction of Streptococcus pneumoniae in upper respiratory tract cultures and a decreased incidence of related acute otitis media following introduction of childhood pneumococcal conjugate vaccines in a Swedish county

BACKGROUND

The effect of pneumococcal conjugate vaccines (PCV) on invasive pneumococcal disease is frequently reported, but the impact on upper respiratory tract infections in a clinical setting is less documented. Our aim in this 5-year observational study was to investigate serotype changes in a large number of Streptococcus pneumoniae upper respiratory tract isolates following sequential introduction of PCV7 and pneumococcal Haemophilus influenza protein D conjugate vaccine (PHiD-CV10) in a Swedish county.

METHODS

All bacterial isolates from the upper respiratory tract (nasopharynx, sinus or middle ear fluid) from patients with respiratory tract infections referred to a clinical microbiology laboratory prior to (2 years 2007-2008; n = 1566) and after introduction of PCV (3 years 2011-2013; n = 1707) were prospectively collected. Microbiological findings were compared between the two periods, and information from clinical referrals was recorded in order to explore changes in incidence of pneumococcal acute otitis media (AOM).

RESULTS

Pneumococcal serotypes covered by PHiD-CV10 decreased from 45 to 12 % prior to and after immunization (p < 0.001), respectively. Despite non-PHiD-CV10 serotypes increased from 49 to 80 %, a significant decline of 35 % in the absolute incidence of pneumocococal isolates (p < 0.001) was observed. Finally, the frequency of complicated AOM caused by S. pneumoniae decreased by 32 % (p < 0.001).

CONCLUSIONS

After introduction of PCV in 2009, we have observed a significantly decreased number of pneumococcal isolates in the upper respiratory tract, a shift to non-PHiD-CV10 serotypes, and a reduction of complicated AOM. Our findings may have implications for future vaccine design.

[Vaccinations in respiratory medicine]

Vaccinations are the most successful and cost-effective measures for prevention of infections. Important pathogens of respiratory tract infections (e.g. influenza viruses and pneumococci) can be effectively treated by vaccinations. The seasonal trivalent and recently now quadrivalent influenza vaccines include antigens from influenza A and B type viruses, which have to be modified annually oriented to the circulating strains. The effective protection by influenza vaccination varies considerably (too short protection time, mismatch); therefore, administration late in the year is the best approach (November/December). Two pneumococcal vaccines are recommended for adults: the over 30-year-old 23-valent polysaccharide vaccine (PPV23) and the 4-year-old 13-valent conjugate vaccine (PCV13). The immunological and clinical efficacy of PPV23 is controversially discussed; however, a moderate reduction of invasive pneumococcal infections is widely accepted. The PCV13 stimulates a T-cell response and has currently demonstrated its clinical efficacy in an impressive study (CAPiTA). The problem of PCV13 is the relatively limited coverage of only 47% of the currently circulating invasive pneumococcal serotypes.

Toxins and derivatives in molecular pharmaceutics: Drug delivery and targeted therapy

Protein and peptide toxins offer an invaluable source for the development of actively targeted drug delivery systems. They avidly bind to a variety of cognate receptors, some of which are expressed or even up-regulated in diseased tissues and biological barriers. Protein and peptide toxins or their derivatives can act as ligands to facilitate tissue- or organ-specific accumulation of therapeutics. Some toxins have evolved from a relatively small number of structural frameworks that are particularly suitable for addressing the crucial issues of potency and stability, making them an instrumental source of leads and templates for targeted therapy. The focus of this review is on protein and peptide toxins for the development of targeted drug delivery systems and molecular therapies. We summarize disease- and biological barrier-related toxin receptors, as well as targeted drug delivery strategies inspired by those receptors. The design of new therapeutics based on protein and peptide toxins is also discussed.

A retrospective analysis of hospital discharge records for S. pneumoniae diseases in the elderly population of Florence, Italy, 2010-2012

Invasive pneumococcal diseases (IPD) and community acquired pneumonia (CAP) represent two of the major causes of out-patient visits, hospital admissions and deaths in the elderly. In Tuscany (Italy), in the Local Health Unit of Florence, a project aimed at implementing an active surveillance of pneumococcal diseases in the hospitalized elderly population started in 2013. The aim of this study is to show the results of the retrospective analysis (2010-2012) on hospital discharge records (HDRs) related to diseases potentially due to S. pneumoniae, using a selection of ICD9-CM codes. All ordinary hospitalizations (primary and secondary diagnoses) of the elderly population were included (11 245 HDRs). Among a population of about 200 000 inhabitants ≥65 y, the hospitalization rate (HR) increased with increasing age and was higher in males in all age groups. Almost all hospitalizations (95%) were due to CAP, only 5% were invasive diseases. Only few cases of CAP were specified as related to S. pneumoniae, the percentage was higher in case of meningitis (100%) or septicemia (22%). In-hospital deaths over the three-year period were 1703 (case fatality rate: 15%). The risk of dying, being hospitalized for a disease potentially attributable to pneumococcus (as primary diagnosis) increased significantly with age (P < 0.001), the odds ratio (OR) per increasing age year was 1.06 (95% CI 1.05-1.07) and was higher in patients with co-existing medical conditions with respect to patients without comorbidities. Currently, an active surveillance system on S. pneumoniae diseases with the inclusion of bio-molecular tests (RT-PCR), is a key step to assess the effectiveness of the PCV13 vaccine (13-valent pneumococcal conjugate vaccine) in the elderly population after implementation of vaccination policies. The results of this study will provide the comparator baseline data for the evaluation of a possible immunization programme involving one or more cohorts of the elderly in Tuscany.

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.

Clinical manifestations of invasive pneumococcal disease by vaccine and non-vaccine types

Pneumococcal conjugated vaccines (PCVs) have shown protection against invasive pneumococcal disease by vaccine serotypes, but an increase in non-vaccine serotype disease has been observed. Type-specific effects on clinical manifestation need to be explored. Clinical data from 2096 adults and 192 children with invasive pneumococcal disease were correlated to pneumococcal molecular serotypes. Invasive disease potential for pneumococcal serotypes were calculated using 165 invasive and 550 carriage isolates from children. The invasive disease potential was lower for non-PCV13 compared to vaccine-type strains. Patients infected with non-PCV13 strains had more underlying diseases, were less likely to have pneumonia and, in adults, tended to have a higher mortality. Furthermore, patients infected with pneumococci belonging to clonal serotypes only expressing non-PCV13 capsules had a higher risk for septicaemia and mortality. PCV vaccination will probably lead to a decrease in invasive pneumococcal disease but an alteration in the clinical manifestation of invasive pneumococcal disease. Genetic lineages causing invasive pneumococcal disease in adults often express non-vaccine serotypes, which can expand after vaccination with an increased risk of infection in patients with underlying diseases.