Pneumococcal serotype diversity among adults in various countries, influenced by pediatric pneumococcal vaccination uptake

Cost-effectiveness analysis of 20-valent pneumococcal conjugate vaccine for routine pediatric vaccination programs in Japan

BACKGROUND

The Japanese National Immunization Program currently includes the pediatric 13 valent pneumococcal conjugate vaccine (PCV13) to prevent pneumococcal infections. We aimed to evaluate the cost-effectiveness of 20-valent PCV (PCV20) as a pediatric vaccine versus PCV13.

METHODS

A decision-analytic Markov model was used to estimate expected costs, quality-adjusted life-years (QALYs), and prevented cases and deaths caused by invasive pneumococcal disease, pneumonia, and acute otitis media over a ten-year time horizon from the societal and healthcare payer perspectives.

RESULTS

PCV20 was dominant, i.e. less costly and more effective, over PCV13 (gained 294,599 QALYs and reduced Japanese yen [JPY] 352.6 billion [2.6 billion United States dollars, USD] from the societal perspective and JPY 178.9 billion [USD 1.4 billion] from the payer perspective). Sensitivity and scenario analyses validated the robustness of the base scenario results. When comparing PCV20 with PCV13, the threshold analysis revealed an incremental cost-effectiveness ratio that was within the threshold value (JPY 5 million/QALY) at a maximum acquisition cost of JPY 74,033 [USD 563] (societal perspective) and JPY 67,758 [USD 515] (payer perspective).

CONCLUSIONS

As a pediatric vaccine, PCV20 was dominant over PCV13 regardless of the study perspective.

The impact of vaccination on the burden of invasive pneumococcal disease from a nationwide surveillance program in Lebanon: an unexpected increase in mortality driven by non-vaccine serotypes

BACKGROUND

The impact of pneumococcal conjugate vaccines (PCVs) on the burden of invasive pneumococcal disease (IPD) and serotype distribution was examined across age groups from data collected by the Lebanese Inter-Hospital Pneumococcal Surveillance Program.

METHODS

Between 2005 and 2020, 593 invasive Streptococcus pneumoniae isolates were collected from 79 hospitals throughout Lebanon. Serotypes and antimicrobial resistance (AMR) profiles were identified, and trends compared over 3 eras: PCV7, post-PCV7/ pre-PCV13, and PCV13 eras.

RESULTS

The prevalence of PCV7 serotypes decreased significantly from 43.6% in the PCV7 era to 17.8% during the PCV13 era (p<0.001). PCV13-only serotypes remained stable in the PCV13 compared to the post-PCV7 eras, especially serotypes 1 and 3, whereas non-vaccine types (NVT) increased throughout the study period, especially 24 and 16F. The mortality rate increased substantially from 12.5% (PCV7 era) to 24.8% (PCV13 era). A significant decrease in AMR was observed across the three study eras.

CONCLUSION

PCVs substantially impacted IPD and AMR in vaccinated and unvaccinated populations despite an increase in mortality driven by NVT. Broadening the recommendation of vaccination to include older age-groups, using higher valency vaccines, and implementing stringent antimicrobial stewardship are likely to further impact the burden of IPD.

Pore-forming alpha-hemolysin efficiently improves the immunogenicity and protective efficacy of protein antigens

Highly immunogenic exotoxins are used as carrier proteins because they efficiently improve the immunogenicity of polysaccharides. However, their efficiency with protein antigens remains unclear. In the current study, the candidate antigen PA0833 from Pseudomonas aeruginosa was fused to the α-hemolysin mutant HlaH35A from Staphylococcus aureus to form a HlaH35A-PA0833 fusion protein (HPF). Immunization with HPF resulted in increased PA0833-specific antibody titers, higher protective efficacy, and decreased bacterial burden and pro-inflammatory cytokine secretion compared with PA0833 immunization alone. Using fluorescently labeled antigens to track antigen uptake and delivery, we found that HlaH35A fusion significantly improved antigen uptake in injected muscles and antigen delivery to draining lymph nodes. Both in vivo and in vitro studies demonstrated that the increased antigen uptake after immunization with HPF was mainly due to monocyte- and macrophage-dependent macropinocytosis, which was probably the result of HPF binding to ADAM10, the Hla host receptor. Furthermore, a transcriptome analysis showed that several immune signaling pathways were activated by HPF, shedding light on the mechanism whereby HlaH35A fusion improves immunogenicity. Finally, the improvement in immunogenicity by HlaH35A fusion was also confirmed with two other antigens, GlnH from Klebsiella pneumoniae and the model antigen OVA, indicating that HlaH35A could serve as a universal carrier protein to improve the immunogenicity of protein antigens.

Pneumococcal serotype determines growth and capsule size in human cerebrospinal fluid

Background

The polysaccharide capsule is a major virulence factor of S. pneumoniae in diseases such as meningitis. While some capsular serotypes are more often found in invasive disease, high case fatality rates are associated with those serotypes more commonly found in asymptomatic colonization. We tested whether growth patterns and capsule size in human cerebrospinal fluid depends on serotype using a clinical isolate of S. pneumoniae and its capsule switch mutants.

Results

We found that the growth pattern differed markedly from that in culture medium by lacking the exponential and lysis phases. Growth in human cerebrospinal fluid was reduced when strains lost their capsules. When a capsule was present, growth was serotype-specific: high carriage serotypes (6B, 9 V, 19F and 23F) grew better than low carriage serotypes (7F, 14, 15B/C and 18C). Growth correlated with the case-fatality rates of serotypes reported in the literature. Capsule size in human cerebrospinal fluid also depended on serotype.

Conclusions

We propose that serotype-specific differences in disease severity observed in meningitis patients may, at least in part, be explained by differences in growth and capsule size in human cerebrospinal fluid. This information could be useful to guide future vaccine design.

Vaccination of Adults in General Medical Practice

In vaccinating adults, clinicians face 2 types of challenges: (1) staying current on recommendations for influenza, pneumococcal, hepatitis A and B, zoster, and other vaccines and (2) addressing systemic barriers to implementing practices that increase vaccination rates. Although adult immunization rates remain suboptimal, there has been much good news in adult vaccination recently. New high-dose and adjuvanted influenza vaccines help improve immune response and may reduce influenza complications in older adults. The new recombinant zoster vaccine offers significantly more efficacy against zoster outbreaks and postherpetic neuralgia than zoster vaccine live. Pertussis vaccine given during the third trimester of pregnancy may prevent between 50% and 90% of pertussis infections in infants. Shorter time for completion (1 vs 6 months) of new, adjuvanted hepatitis B vaccine may increase adherence. Clinicians can address systemic barriers to increasing vaccination rates in their clinics and health care systems by following the Centers for Disease Control and Prevention's Standards for Adult Immunization Practice. Clinicians can help increase vaccination rates by writing standing orders and by advocating for nurses or medical assistants to receive training and protected time for assessing and documenting vaccination histories and administration. Strong recommendations that presume acceptance of vaccination are effective with most patients. Communication techniques similar to motivational interviewing can help with vaccine-hesitant patients. Clinicians, as experts on providing preventive services, can educate community leaders about the benefits of immunization and can inform vaccine experts about challenges of implementing vaccination recommendations in clinical practice and strategies that can work to raise vaccination rates.

Prevalence of pneumococcal serotypes in adults ≥50 years of age

CONTEXT

Currently, majority of studies on antibiotic resistance and serotype prevalence in Streptococcus pneumoniae are in paediatric population and there is limited epidemiologic data pertaining to elderly Indian population.

AIMS

This study was undertaken to assess antibiotic resistance pattern and the coverage of the polysaccharide vaccine 23 (PPV23) in the elderly population.

SETTINGS AND DESIGN

This was a prospective 2-year pneumococcal surveillance study in patients with community-acquired pneumococcal infections of ≥50 years' age group on fifty isolates of S. pneumoniae.

MATERIALS AND METHODS

Antibiotic susceptibility by Kirby-Bauer disc diffusion method and minimum inhibitory concentration susceptibility testing by E-test method were performed for various antibiotics. All isolates were serotyped by the capsular Quellung method with commercial antisera.

RESULTS

All S. pneumoniae isolates were sensitive to penicillin and ceftriaxone. Non-susceptibility to levofloxacin, co-trimoxazole, erythromycin and clindamycin was noted as 16%, 74%, 10% and 6%, respectively. Prevalence of multidrug resistance in S. pneumoniae was observed as 6%. The most common serotypes observed in our study were 19A (14%), 8 (10%), 19F (8%), 3 (6%) and 9N (6%). PCV7, PCV10, PCV13 and PCV23 coverage was observed as 16%, 24%, 48% and 66%, respectively. The non-vaccine serotypes (NVTs) comprised 30% (n = 15) of the isolates.

CONCLUSIONS

Our study shows different antibiotic susceptibility patterns of S. pneumoniae as compared to other neighbouring regions in Asia. The modest coverage of S. pneumoniae serotypes by PPV23 vaccine and prevalence of diverse NVTs in adult population make it a challenging task to recommend further changes in the future vaccine.

[Pneumococcal disease in adults: Risk levels and vaccine recommendations]

Actualmente 2 vacunas antineumocócicas están disponibles para uso en adultos: la «clásica» vacuna neumocócica polisacárida tricosavalente (VNP23) y la «nueva» vacuna neumocócica conjugada tridecavalente (VNC13). La principal ventaja de la VNC13 sería su potencial mejor inmunogenicidad, siendo sus principales inconvenientes el elevado coste y la baja cobertura de serotipos en comparación con la VNP23. Las evidencias actualmente disponibles apoyan las siguientes recomendaciones básicas: a) en los adultos con más alto riesgo (básicamente inmunocompromiso y/o asplenia) se recomienda la vacunación dual con ambas vacunas; b) en los sujetos con riesgo elevado (básicamente personas > 65 años y pacientes de 15-64 años con enfermedad pulmonar o cardiaca crónica, diabetes y/o alcoholismo) se recomienda la vacunación simple con VNP23 (dosis única en primovacunados ≥ 65 años; revacunación a los 5-10 años en el caso de primovacunados antes de los 65 años), y c) en el resto de adultos (riesgo normal/bajo) no se recomienda la vacunación.

Characteristics of serogroup 20 S.pneumoniae isolates from Brazil

Background

Although serogroup 20 is not part of any conjugate pneumococcal vaccine, its serotype 20A, but not 20B, belongs to the polysaccharide 23-valent formula. Little is known about its clinical, laboratorial and epidemiological characteristics.

Methods

The purpose of this study was to evaluate the bacterial genotypes (by PFGE and MLST), clinical characteristics of patients (from review of medical records) and antimicrobial susceptibility of serogroup 20 isolates which were recovered from patients with invasive pneumococcal disease (IPD) from 2007 to 2012. Subtyping to determine 20A and 20B types was also performed by sequencing the genes of the cps locus.

Results

Sixteen isolates were genotyped and were highly related. All pneumococci were resistant to tetracycline and 31 % were non-susceptible to trimethoprim/sulfamethoxazole. Penicillin MIC ranged from 0.004 to 1 μg/mL and non-susceptibility (MIC ≥ 0.12 μg/mL) was observed in 5/16 isolates (31 %). All isolates belonged to subtype 20B. Most patients were male with a median age of 62 years and presented at least one underlying disease (mostly respiratory conditions). All isolates belonged to ST8889 and to a unique PFGE clone.

Conclusions

A high clonal occurrence of serotype 20B pneumococci recovered from patients with IPD in Brazil was observed. As a non-PCV10 serotype, selective pressure may be responsible for this unusual occurrence of serogroup 20. However, temporal variation effect should not be underestimated; therefore it is an issue that warrants continued monitoring.

Pneumococcal vaccination coverages among low-, intermediate-, and high-risk adults in Catalonia

There is scarce data about pneumococcal vaccination coverages among adults in recent years. We investigated current pneumococcal vaccination coverages in Catalonia, Spain, with a cross-sectional population-based study including 2,033,465 individuals aged 50 y or older assigned to the Catalonian Health Institute at 01/01/2015 (date of survey). A previously validated institutional research clinical Database was used to classify study subjects by their vaccination status for both 23-valent pneumococcal polysaccharide vaccine (PPSV23) and 13-valent pneumococcal conjugate vaccine (PCV13), to identify comorbidities and underlying conditions, and establish the risk stratum of each individual: High risk stratum: functional or anatomic asplenia, cochlear implants, CSF leaks, or immunocompromising conditions; medium risk stratum: immunocompetent persons with history of chronic cardiac or respiratory disease, liver disease, diabetes mellitus, alcoholism and/or smoking; low risk stratum: persons without high or medium risk conditions. Of the total 2,033,465 study population, an amount of 789,098 (38.8%) had received PPVS23, whereas 5031 (0.2%) had received PCV13. PPSV23 coverages increased largely with increasing age: 4.8% in 50-59 y vs 35.5% in 60-69 y vs 71.9% in 70-79 y vs 79.5% in 80 y or older; p < 0.001). PCV13 coverages also increased with age, although they were very low in all age groups. PPSV23 coverages were 59.2% in high risk stratum, 48.3% in medium risk stratum and 28.1% in low risk stratum (p < 0.001). For the PCV13, uptakes were 1.2%, 0.3% and 0.1% in high, medium and low stratum, respectively (p < 0.001). In conclusion, pneumococcal vaccination coverages in Catalonian adults are not optimal, being especially small for the PCV13 (even in high-risk subjects).

Serotype Changes and Drug Resistance in Invasive Pneumococcal Diseases in Adults after Vaccinations in Children, Japan, 2010-2013

Pneumococcal conjugate vaccination of children is associated with penicillin-resistant Streptococcus pneumoniae in adults.

After 7-valent pneumococcal conjugate vaccine (PCV) for children was introduced in Japan in November 2010, we examined changes in Streptococcus pneumoniae serotypes and in genetic antimicrobial drug resistance of isolates from adults with invasive pneumococcal diseases. During April 2010–March 2013, a total of 715 isolates were collected from adults with invasive pneumococcal diseases. Seven-valent PCV serotypes in adults decreased from 43.3% to 23.8%, most noticeably for serotype 6B. Concomitantly, 23-valent pneumococcal polysaccharide vaccine (PPSV23) serotypes decreased from 82.2% to 72.2%; non-PPSV23 serotypes increased from 13.8% to 25.1%. Parallel with serotype changes, genotypic penicillin-resistant S. pneumoniae decreased from 32.4% to 21.1%, and 6 non-PPSV23 serotypes emerged (6D, 15A, 15C, 16F, 23A, and 35B). Respective vaccine coverage rates for 13-valent PCV and PPSV23 differed by disease: 73.9% and 84.3% for patients with pneumonia, 56.4% and 69.2% for patients with bacteremia and sepsis, and 45.7% and 69.3% for patients with meningitis.

Vaccination of adults with 23-valent pneumococcal polysaccharide vaccine induces robust antibody responses against pneumococcal serotypes associated with serious clinical outcomes

PNEUMOVAX™ 23, a 23-valent polysaccharide pneumococcal vaccine (PPV23), covers 65% to 91% of the isolates recovered from adult cases of invasive pneumococcal disease. Several studies have demonstrated that pneumococcal serotypes 31, 11A, 35F, 17F, 3, 16F, 19F, 15B, and 10A are associated with higher case-fatality or meningitis rates than other pneumococcal serotypes. This study (U05-PnPS-403; EudraCT: 2008-003648-12) evaluated the immune response followings administration of PPV23 for 4 of these serotypes (10A, 11A, 15B, and 17F), that are included in PPV23 but not in licensed pneumococcal conjugate vaccines. Serotype-specific IgG geometric mean concentrations (GMCs) and geometric mean fold-rises (GMFRs) for these 4 serotypes were measured by a validated enzyme-linked immunosorbent assay (ELISA) in 104 subjects >50 y of age who were enrolled in a study evaluating the safety and immunogenicity of a single-dose of PPV23. At 1 month post-vaccination, GMCs for serotypes10A, 11A, 15B and 17F were 6.5, 4.3, 14.7, and 5.1 µg/mL, respectively. GMFRs from baseline were 9.0, 4.5, 8.4, and 11.5, respectively. The percentages of subjects achieving >2-fold increases in IgG GMCs between pre-vaccination and 1 month post-vaccination were 90%, 85%, 88% and 89%, respectively. In conclusion, PPV23 induces a robust immune response in adults to pneumococcal serotypes 10A, 11A, 15B, and 17F, which have been associated with elevated case-fatality or meningitis rates.

A chimeolysin with extended-spectrum streptococcal host range found by an induced lysis-based rapid screening method

The increasing emergence of multi-drug resistant streptococci poses a serious threat to public health worldwide. Bacteriophage lysins are promising alternatives to antibiotics; however, their narrow lytic spectrum restricted to closely related species is a central shortcoming to their translational development. Here, we describe an efficient method for rapid screening of engineered chimeric lysins and report a unique “chimeolysin”, ClyR, with robust activity and an extended-spectrum streptococcal host range against most streptococcal species, including S. pyogenes, S. agalactiae, S. dysgalactiae, S. equi, S. mutans, S. pneumoniae, S. suis and S. uberis, as well as representative enterococcal and staphylococcal species (including MRSA and VISA). ClyR is the first lysin that demonstrates activity against the dominant dental caries-causing pathogen as well as the first lysin that kills all four of the bovine mastitis-causing pathogens. This study demonstrates the success of the screening method resulting in a powerful lysin with potential for treating most streptococcal associated infections.

Usefulness of pneumococcal antigen urinary testing in the intensive care unit?

OBJECTIVES

The use of pneumococcal antigen urinary tests is substantially increasing and is associated with a significant cost. The relevant use of this test in the intensive care unit (ICU) should be better defined. Our aim was to define the role of this test in relation to other microbiological tests. We described a series of patients admitted to the ICU for an invasive pneumococcal disease (IPD).

PATIENTS AND METHODS

We conducted a retrospective and descriptive study of the microbiological tests used to diagnose IPD in patients admitted to the ICU of the University Hospital in Bordeaux. Our aim was to measure the sensitivity of these bacteriological tests and of the BinaxNOWS. pneumoniae test.

RESULTS

Between 2009 and 2013, 148 patients were admitted for an IPD. A lower respiratory tract infection was diagnosed in 96.6% of them (143 patients). The overall ICU case fatality rate was 17.6%. The sensitivity of the pneumococcal antigen urinary test, sputum bacteriological examination, and blood cultures was respectively 83%, 37.6%, and 29.7%. S. pneumoniae was isolated from at least one bacteriological sample in 48.6% of patients, but in 51.4%, the diagnosis was only based on the results of the pneumococcal antigen urinary test.

CONCLUSION

We suggest performing a pneumococcal antigen urinary test when an IPD is suspected, only if the bacteriological tests are still negative after 48hours. This strategy would result in a substantial cost saving. Patients would not face any additional risks as the result of the pneumococcal antigen urinary test does not have any impact on the initially prescribed antibiotic therapy.

Clinical usefulness of pneumococcal urinary antigen test, stratified by disease severity and serotypes

Early diagnosis of pneumococcal pneumonia facilitates appropriate antibiotic therapy. The urinary antigen test (UAT) is known to be useful for the diagnosis of pneumococcal pneumonia. This study aimed to evaluate the usefulness of UAT in the 13-valent pneumococcal conjugated vaccine (PCV13) era. Community-acquired pneumonia (CAP) cases aged ≥19 years were reviewed retrospectively. This study evaluated the utility of Streptococcus pneumoniae UAT (BinaxNOW^® assay) for diagnosis of pneumococcal CAP, and the relation of the UAT positive rate to age, comorbidities, pneumonia severity, and pneumococcal serotypes. Among 752 microbiologically identified CAP cases, S. pneumoniae (36.7%) was the most common isolate, and of those cases, 56.4% were positive for UAT. UAT positivity varied by pneumococcal serotype (serotype 3, 50%; 9V/9A, 85%; 11A/11E, 54%; 14, 36.4%; 19A, 50%; and 23F, 37.5%), and was significantly increased since 2012, two years after introduction of PCV13. The positive rate of UAT was significantly related to CRP level (P = 0.007) and lobar pneumonia (P = 0.006), but not to age, co-morbidities or prior antibiotic therapy. In conclusion, urinary antigen detection varied depending on the S. pneumoniae serotype. In the PCV13 era, the serotype distribution of pneumococcal pneumonia may be changing, and the clinical usefulness of UAT needs to be monitored. The positive rate of UAT may be influenced by a localized bacterial burden and host reactions.

Impact of pneumococcal conjugate vaccine on pediatric tympanostomy tube insertion in partial immunized population

Objective. To investigate the impact of seven-valent pneumococcal conjugate vaccine on tube insertions in a partial immunized pediatric population. Study Design. Retrospective ecological study. Methods. This study used Taiwan National Health Insurance Research Database for the period 2000–2009. Every child under 17 years old who received tubes during this 10-year period was identified and analyzed. The tube insertion rates in different age groups and the risk to receive tubes in different birth cohorts before and after the release of the vaccine in 2005 were compared. Results. The tube insertion rates for children under 17 years of age ranged from 21.6 to 31.9 for 100,000 persons/year. The tube insertion rate of children under 2 years old decreased significantly after 2005 in period effect analysis (β = −0.074, P < 0.05, and the negative β value means a downward trend) and increased in children 2 to 9 years old throughout the study period (positive β values which mean upward trends, P < 0.05). The rate of tube insertion was lower in 2004-2005 and 2006-2007 birth cohorts than that of 2002-2003 birth cohort (RR = 0.90 and 0.21, 95% CI 0.83–0.97 and 0.19–0.23, resp.). Conclusion. The seven-valent pneumococcal conjugate vaccine may reduce the risk of tube insertion for children of later birth cohorts. The vaccine may have the protective effect on tube insertions in a partial immunized pediatric population.

The burden and etiology of community-onset pneumonia in the aging Japanese population: a multicenter prospective study

BACKGROUND

The increasing burden of pneumonia in adults is an emerging health issue in the era of global population aging. This study was conducted to elucidate the burden of community-onset pneumonia (COP) and its etiologic fractions in Japan, the world's most aged society.

METHODS

A multicenter prospective surveillance for COP was conducted from September 2011 to January 2013 in Japan. All pneumonia patients aged ≥ 15 years, including those with community-acquired pneumonia (CAP) and health care-associated pneumonia (HCAP), were enrolled at four community hospitals on four major islands. The COP burden was estimated based on the surveillance data and national statistics.

RESULTS

A total of 1,772 COP episodes out of 932,080 hospital visits were enrolled during the surveillance. The estimated overall incidence rates of adult COP, hospitalization, and in-hospital death were 16.9 (95% confidence interval, 13.6 to 20.9), 5.3 (4.5 to 6.2), and 0.7 (0.6 to 0.8) per 1,000 person-years (PY), respectively. The incidence rates sharply increased with age; the incidence in people aged ≥ 85 years was 10-fold higher than that in people aged 15-64 years. The estimated annual number of adult COP cases in the entire Japanese population was 1,880,000, and 69.4% were aged ≥ 65 years. Aspiration-associated pneumonia (630,000) was the leading etiologic category, followed by Streptococcus pneumoniae-associated pneumonia (530,000), Haemophilus influenzae-associated pneumonia (420,000), and respiratory virus-associated pneumonia (420,000), including influenza-associated pneumonia (30,000).

CONCLUSIONS

A substantial portion of the COP burden occurs among elderly members of the Japanese adult population. In addition to the introduction of effective vaccines for S. pneumoniae and influenza, multidimensional approaches are needed to reduce the pneumonia burden in an aging society.

[Incidence and lethality of invasive pneumococcal disease in Tarragona, Spain, 2006-2009]

An epidemiological study was conducted on all cases of invasive pneumococcal disease (IPD) diagnosed in Tarragona, Spain, between 1 January 2006 and 31 December 2009. A total of 286 IPD cases were observed, which was an overall incidence of 21.2 episodes per 100,000 persons-year (95% CI: 16.6-26.9). Incidence rates were 26.3/100,000 (95% CI: 14.4-44.3) among children, 12.2/100,000 (95% CI: 8.2-17.6) among patients between 15-64 years and 59.6/100,000 (95% CI: 40.0-85.8) in those ≥65 years. Overall lethality rate was 7.3% (none in children, 3.4% among patients 15-64 years, and 14.8% among patients ≥65 years; p<0.001).

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.

An ahemolytic pneumolysin of Streptococcus pneumoniae manipulates human innate and CD4⁺ T-cell responses and reduces resistance to colonization in mice in a serotype-independent manner

BACKGROUND

Some Streptococcus pneumoniae serotypes express an ahemolytic pneumolysin (PLYa). Serotypes that commonly express PLYa, including serotype 8 (ST8) and ST1, are often associated with a low prevalence during colonization but a higher propensity to cause invasive disease. We sought to study the host response to ST8 PLYa in a homologous and heterologous capsular background.

METHODS

We genetically exchanged the PLYa of ST8 strain 6308 with the hemolytic PLY (PLYh) of ST3 A66.1 and vice versa and determined the impact of the exchange on nasopharyngeal colonization in mice. Then, to compare the response of human cells to PLYa-expressing and PLYh-expressing strains, we infected human peripheral blood mononuclear cells (PBMCs) with PLY-switched strains and assessed dendritic cell and CD4(+) T-cell responses by intracellular cytokine staining.

RESULT

Mice colonized with PLYa-expressing strains had significantly higher colonization densities than those colonized with PLYh-expressing strains, irrespective of capsular background. Compared with infection of PBMCs with PLYh-expressing strains, infection with PLYa-expressing strains induced diminished innate (dendritic cell cytokines, costimulatory receptor, and apoptotic) and adaptive (CD4(+) T-cell proliferative and memory interleukin 17A) responses.

CONCLUSION

Our findings demonstrate that PLYa has the potential to manipulate host immunity irrespective of capsule type. PLY exchange between STs expressing PLYa and PLYh could lead to unexpected colonization or invasion phenotypes.

Differences in serious clinical outcomes of infection caused by specific pneumococcal serotypes among adults

BACKGROUND

Infections due to Streptococcus pneumoniae serotypes differ in clinical manifestations among adults, varying in propensity for severity, invasiveness, and lethality. To characterize differences in serious outcomes between pneumococcal serotypes, we systematically reviewed the literature.

METHODS

After distilling 676 hits to 28 relevant articles, statistically significant differences in individual serotypes associated with serious clinical outcomes were assessed. Serotypes associated with elevated risk of serious clinical outcomes were evaluated in terms of serotypes included in licensed adult pneumococcal vaccines (i.e., 23-valent pneumococcal polysaccharide vaccine (PPSV23) and 13-valent pneumococcal conjugate vaccine (PCV13)). Repeated findings were considered a measure of robustness.

RESULTS

Among adult studies evaluating serious clinical outcomes, the following serotypes were associated with elevated risk: Empyema (serotypes 1, 3, 5, 7F, 8, 19A), necrotizing pneumonia (serotype 3), septic shock (serotypes 3, 19A), meningitis (repeatedly serotypes 10A, 15B, 19F, 23F), reduced quality-adjusted life years (QALYs, serotypes 15B, 3, 10A, 9N, 19F, 11A, 31), and increased case-fatality rates (repeatedly serotypes 3, 6B, 9N, 11A, 16F, 19F, 19A).

CONCLUSION

Both vaccine formulations include multiple pneumococcal serotypes associated with increased risk for serious clinical outcomes. Three studies found elevated risk from serotype 6A (unique to PCV13). Fourteen studies found elevated risk from nine serotypes unique to PPSV23 (repeatedly: case-fatality-11A & 9N, meningitis-10A & 15B). Seven studies found elevated risk from serotypes not represented in either vaccine formulation (notably 16F). The pneumococcal serotypes repeatedly associated with elevated risk of serious outcomes in adults are an important consideration for vaccine policy making.