Effects of Infant Pneumococcal Conjugate Vaccination on Serotype Distribution in Invasive Pneumococcal Disease among Children and Adults in Germany

Pneumococcal serotypes and risk factors in adult community-acquired pneumonia 2018-20; a multicentre UK cohort study

Background

Higher-valency pneumococcal vaccines are anticipated. We aimed to describe serotype distribution and risk factors for vaccine-serotype community-acquired pneumonia (CAP) in the two years pre-SARS-CoV-2 pandemic.

Methods

We conducted a prospective cohort study of adults hospitalised with CAP at three UK sites between 2018 and 2020. Pneumococcal serotypes were identified using a 24-valent urinary-antigen assay and blood cultures. Risk factors associated with vaccine-type pneumonia caused by serotypes in the 13-, 15- and 20-valent pneumococcal conjugate vaccines (PCV13, PCV15, PCV20) and 23-valent pneumococcal polysaccharide vaccine (PPV23) were determined from multivariable analysis.

Findings

Of 1921 adults hospitalised with CAP, 781 (40.7%, 95% confidence intervals (CI) 38.5-42.9%) had pneumococcal pneumonia. A single PCV13-serotype was detected in 242 (31.0%, 95% CI 27.8-34.3%) pneumococcal CAP patients, mostly serotype 3 (171/242, 70.7%, 95% CI 64.5-76.0%). The additional two PCV15-serotypes were detected in 31 patients (4%, 95% CI 2.8-5.6%), and PCV20-non13-serotypes in 192 (24.6%), with serotype 8 most prevalent (123/192, 64.1%, 95% CI 57.1-70.5%). Compared to PCV13-serotype CAP, people with PCV20-non13 CAP were younger (median age 62 versus 72 years, p < 0.001) and less likely to be male (44% versus 61%, p = 0.01). PPV23-non13-serotypes were found in 252 (32.3%, 95% CI 29.1-35.6%) pneumococcal CAP patients.

Interpretation

Despite mature infant pneumococcal programmes, the burden of PCV13-serotype pneumonia remains high in older adults, mainly due to serotype 3. PCV20-non13-serotype pneumonia is more likely in younger people with fewer pneumococcal risk factors.

Funding

Unrestricted investigator-initiated research grant from Pfizer, United Kingdom; support from National Institute for Health Research (NIHR) Biomedical Research Centre, Nottingham.

Serotype Distribution and Disease Severity in Adults Hospitalized with Streptococcus pneumoniae Infection, Bristol and Bath, UK, 2006‒2022

Pneumococcal conjugate vaccinations should be evaluated and considered in formulating future public health policy recommendations.

Ongoing surveillance after pneumococcal conjugate vaccination (PCV) deployment is essential to inform policy decisions and monitor serotype replacement. We report serotype and disease severity trends in 3,719 adults hospitalized for pneumococcal disease in Bristol and Bath, United Kingdom, during 2006–2022. Of those cases, 1,686 were invasive pneumococcal disease (IPD); 1,501 (89.0%) had a known serotype. IPD decreased during the early COVID-19 pandemic but during 2022 gradually returned to prepandemic levels. Disease severity changed throughout this period: CURB65 severity scores and inpatient deaths decreased and ICU admissions increased. PCV7 and PCV13 serotype IPD decreased from 2006–2009 to 2021–2022. However, residual PCV13 serotype IPD remained, representing 21.7% of 2021–2022 cases, indicating that major adult PCV serotype disease still occurs despite 17 years of pediatric PCV use. Percentages of serotype 3 and 8 IPD increased, and 19F and 19A reemerged. In 2020–2022, a total of 68.2% IPD cases were potentially covered by PCV20.

Impact of the progressive uptake of pneumococcal conjugate vaccines on the epidemiology and antimicrobial resistance of invasive pneumococcal disease in Gipuzkoa, northern Spain, 1998-2022

Objectives

To analyze the impact of pneumococcal conjugate vaccines (PCVs) on the incidence of invasive pneumococcal diseases (IPDs) and pneumococcal antibiotic resistance in Gipuzkoa, northern Spain for a 25 years period.

Methods

All cases of IPD confirmed by culture between 1998 and 2022 in a population of around 427,416 people were included. Pneumococci were serotyped and antimicrobial susceptibility was assessed by the EUCAST guidelines.

Results

Overall, 1,516 S. pneumoniae isolates were collected. Annual IPD incidence rates (per 100,000 people) declined from 19.9 in 1998-2001 to 11.5 in 2017-19 (42.2% reduction), especially in vaccinated children (from 46.7 to 24.9) and non-vaccinated older adult individuals (from 48.0 to 23.6). After PCV13 introduction, the decrease in the incidence of infections caused by PCV13 serotypes was balanced by the increase in the incidence of non-PCV13 serotypes. In the pandemic year of 2020, IPD incidence was the lowest: 2.81. The annual incidence rates of penicillin-resistant isolates also decreased, from 4.91 in 1998-2001 to 1.49 in 2017-19 and 0.70 in 2020. Since 2017, serotypes 14, 19A, and 11A have been the most common penicillin-resistant types. The incidence of erythromycin-resistant strains declined, from 3.65 to 1.73 and 0.70 in the same years.

Conclusion

PCV use was associated with declines in the incidence of IPD and the spread of non-vaccine serotypes, that balanced the beneficial effect off PCV13, some of them showing high rates of antibiotic resistance.

Safety and immunogenicity of a multivalent pneumococcal conjugate vaccine given with 13-valent pneumococcal conjugate vaccine in healthy infants: A phase 2 randomized trial

Use of pneumococcal conjugate vaccines (PCVs) has led to substantial reductions in the global burden of pediatric pneumococcal disease. Expansion of serotype coverage has been achieved by increasing PCV valency, but this may carry the potential risk of antibody interference. A complementary 7-valent PCV (cPCV7) including polysaccharide conjugates from 7 non-13-valent (PCV13) serotypes was developed to potentially complement PCV13-mediated protection and expand serotype coverage. This study evaluated cPCV7 and PCV13 coadministered in separate limbs or separated in time in infants. This phase 2, multicenter, open-label study included 512 infants randomized 1:1:1 to receive cPCV7 coadministered with PCV13 at ages 2, 4, 6, and 12 months (cPCV7 Coadministered); cPCV7 given at ages 3, 5, 7, and 13 months, 3‒5 weeks after PCV13 (cPCV7 Separated); or PCV13 at ages 2, 4, 6, and 12 months followed by a single supplemental dose of cPCV7 at 13 months (PCV13 Control). Safety evaluations included local reactions, systemic events, and adverse events. Serotype-specific immunoglobulin G concentrations and opsonophagocytic activity titers were assessed. The safety profile of cPCV7 was similar to that of PCV13. cPCV7 was well-tolerated in infants when coadministered with or given separately from PCV13. Robust and functional immune responses for all cPCV7 serotypes were observed in both cPCV7 groups. No immunologic interference was observed for either the cPCV7 or PCV13 serotypes with coadministration. A single cPCV7 dose induced immune responses in toddlers. These findings support potential coadministration of a complementary PCV to supplement protection provided by existing PCVs.Trial registration: ClinicalTrials.gov, NCT03550313.

Mathematical modeling of pneumococcal transmission dynamics in response to PCV13 infant vaccination in Germany predicts increasing IPD burden due to serotypes included in next-generation PCVs

INTRODUCTION

Two next-generation pneumococcal conjugate vaccines (PCVs), a 15- and a 20-valent PCV (PCV15 and PCV20), have recently been licensed for use in adults, and PCV15 has also been licensed in children. We developed a dynamic transmission model specific for Germany, with the aim to predict carriage prevalence and invasive pneumococcal disease (IPD) burden for serotypes included in these vaccines.

METHODS

The model allows to follow serotype distributions longitudinally both in the absence and presence of PCV vaccinations. We considered eight age cohorts and seven serotype groups according to the composition of different pneumococcal vaccines. This comprises the additional serotypes contained in PCV15 and PCV20 but not in PCV13.

RESULTS

The model predicted that by continuing the current vaccine policy (standard vaccination with PCV13 in children and with PPSV23 in adults) until 2031, IPD case counts due to any serotype in children <2 years of age will remain unchanged. There will be a continuous decrease of IPD cases in adults aged 16-59y, but a 20% increase in adults ≥60y. Furthermore, there will be a steady decrease of the proportion of carriage and IPD due to serotypes included in PCV7 and PCV13 over the model horizon and a steady rise of non-PCV13 serotypes in carriage and IPD. The highest increase for both pneumococcal carriage and absolute IPD case counts was predicted for serotypes 22F and 33F (included in both PCV15 and PCV20) and serotypes 8, 10A, 11A, 12F, and 15B (included in PCV20 only), particularly in older adults. Between 2022 and 2031, serotypes included in PCV20 only are expected to cause 19.7-25.3% of IPD cases in adults ≥60y.

CONCLUSIONS

We conclude that introduction of next-generation PCVs for adults may prevent a substantial and increasing proportion of adult IPDs, with PCV20 having the potential to provide the broadest protection against pneumococcal disease.

Invasive pneumococcal infections in France: Changes from 2009 to 2021 in antibiotic resistance and serotype distribution of Streptococcus pneumoniae based on data from the French Regional Pneumococcal Observatories network

OBJECTIVE

The 23 French Regional Pneumococcal Observatories (ORPs) analyzed antibiotic resistance and serotypes of Streptococcus pneumoniae strains isolated from invasive infections in France over a 12-year period.

METHODS

Between 2009 and 2021, the ORPs analyzed 19,319 strains, including 1,965 in children and 17,354 in adults. Strains were assessed for their resistance to penicillin G, amoxicillin and cefotaxime. Serotypes were identified in collaboration with the National Reference Centre.

RESULTS

During this period, the number of strains collected yearly decreased significantly. The decrease was particularly pronounced up until 2013, especially in children (-61.0%). However, penicillin non-susceptible strains (PNSPs) increased in children (24.7% in 2009 vs 45.0% in 2021, p < 0.0001) and in adults (27.1% in 2009 vs 31.3% in 2021, p < 0.05), as well as resistance (I + R) to amoxicillin (children: 12.5% in 2009 vs 19.4% in 2021, p < 0.05; adults: 13.4% in 2009 vs 14.5% in 2021, NS) and resistance (I + R) to cefotaxime (children: 8.0% in 2009 vs 13.1% in 2021, p < 0.05; adults: 7.1% in 2009 vs 11.9% in 2021, p < 0.0001). All in all, the proportion of strains belonging to serotypes present in the PCV13 vaccine has fallen sharply, from 64.8% in 2009 to 23.6 % in 2021. At the same time, serotypes such as 8, 10A, 11A, 15B/C and 9N, not included in PCV13, were increasing.

CONCLUSION

During the study period, data collected by the network highlighted an increase of invasive PNSPs in children and non-vaccine serotypes. Surveillance of resistance and serotypes remains instrumental, particularly to monitor the evolution of vaccine efficacy.

Factors affecting antimicrobial resistance in Streptococcus pneumoniae following vaccination introduction

Streptococcus pneumoniae is a major cause of pneumonia, meningitis, and septicaemia worldwide. Pneumococcal antimicrobial resistance (AMR) has been highlighted by the WHO as an important public health concern, with emerging serotypes showing resistance to multiple antibiotics. Indeed, although the introduction of pneumococcal conjugate vaccines (PCVs) has been associated with an overall decline in pneumococcal AMR, there have been increases in prevalence of potentially disease-causing AMR serotypes not targeted by vaccination. Here, we discuss a variety of evolutionary mechanisms at the host, pathogen, and environmental levels that may contribute to changes in the prevalence of pneumococcal AMR in the post-vaccination era. The relative importance of these factors may vary by population, pneumococcal lineage, geography, and time, leading to the complex relationship between vaccination, antibiotic use, and AMR.

Emergence of a multidrug-resistant and virulent Streptococcus pneumoniae lineage mediates serotype replacement after PCV13: an international whole-genome sequencing study

BACKGROUND

Serotype 24F is one of the emerging pneumococcal serotypes after the introduction of pneumococcal conjugate vaccine (PCV). We aimed to identify lineages driving the increase of serotype 24F in France and place these findings into a global context.

METHODS

Whole-genome sequencing was performed on a collection of serotype 24F pneumococci from asymptomatic colonisation (n=229) and invasive disease (n=190) isolates among individuals younger than 18 years in France, from 2003 to 2018. To provide a global context, we included an additional collection of 24F isolates in the Global Pneumococcal Sequencing (GPS) project database for analysis. A Global Pneumococcal Sequence Cluster (GPSC) and a clonal complex (CC) were assigned to each genome. Phylogenetic, evolutionary, and spatiotemporal analysis were conducted using the same 24F collection and supplemented with a global collection of genomes belonging to the lineage of interest from the GPS project database (n=25 590).

FINDINGS

Serotype 24F was identified in numerous countries mainly due to the clonal spread of three lineages: GPSC10 (CC230), GPSC16 (CC156), and GPSC206 (CC7701). GPSC10 was the only multidrug-resistant lineage. GPSC10 drove the increase in 24F in France and had high invasive disease potential. The international dataset of GPSC10 (n=888) revealed that this lineage expressed 16 other serotypes, with only six included in 13-valent PCV (PCV13). All serotype 24F isolates were clustered in a single clade within the GPSC10 phylogeny and long-range transmissions were detected from Europe to other continents. Spatiotemporal analysis showed GPSC10-24F took 3-5 years to spread across France and a rapid change of serotype composition from PCV13 serotype 19A to 24F during the introduction of PCV13 was observed in neighbouring country Spain.

INTERPRETATION

Our work reveals that GPSC10 alone is a challenge for serotype-based vaccine strategy. More systematic investigation to identify lineages like GPSC10 will better inform and improve next-generation preventive strategies against pneumococcal diseases.

FUNDING

Bill & Melinda Gates Foundation, Wellcome Sanger Institute, and the US Centers for Disease Control and Prevention.

Development and Validation of a Sensitive and Robust Multiplex Antigen Capture Assay to Quantify Streptococcus pneumoniae Serotype-Specific Capsular Polysaccharides in Urine

Streptococcus pneumoniae is a major cause of community-acquired pneumonia (CAP) in young children, older adults, and those with immunocompromised status. Since the introduction of pneumococcal vaccines, the burden of invasive pneumococcal disease caused by vaccine serotypes (STs) has decreased; however, the effect on the burden of CAP is unclear, potentially due to the lack of testing for pneumococcal STs. We describe the development, qualification, and clinical validation of a high-throughput and multiplex ST-specific urine antigen detection (SSUAD) assay to address the unmet need in CAP pneumococcal epidemiology. The SSUAD assay is sensitive and specific to the 15 STs in the licensed pneumococcal conjugate vaccine V114 (STs 1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, 22F, 23F, and 33F) and uses ST-specific monoclonal antibodies for rapid and simultaneous quantification of the 15 STs using a Luminex microfluidics system. The SSUAD assay was optimized and qualified using healthy adult urine spiked with pneumococcal polysaccharides and validated using culture-positive clinical urine samples (n = 34). Key parameters measured were accuracy, precision, sensitivity, specificity, selectivity, and parallelism. The SSUAD assay met all prespecified validation acceptance criteria and is suitable for assessments of disease burden associated with the 15 pneumococcal STs included in V114.

IMPORTANCEStreptococcus pneumoniae has more than 90 serotypes capable of causing a range of disease manifestations, including otitis media, pneumonia, and invasive diseases, such as bacteremia or meningitis. Only a minority (<10%) of pneumococcal diseases are bacteremic with known serotype distribution. Culture and serotyping of respiratory specimens are neither routine nor reliable. Hence, the serotype-specific disease burden of the remaining (>90%) noninvasive conditions is largely unknown without reliable laboratory techniques. To address this need, a 15-plex urine antigen detection assay was developed and validated to quantify pneumococcal serotype-specific capsular polysaccharides in urine. This assay will support surveillance to estimate the pneumococcal disease burden and serotype distribution in nonbacteremic conditions. Data obtained from this assay will be critical for understanding the impact of pneumococcal vaccines on noninvasive pneumococcal diseases and to inform the choice of pneumococcal serotypes for next-generation vaccines.

Non-invasive pneumococcal pneumonia due to vaccine serotypes: A systematic review and meta-analysis

BACKGROUND

Non-invasive pneumococcal pneumonia causes significant morbidity and mortality in older adults. Understanding pneumococcal sero-epidemiology in adults ≥50 years is necessary to inform vaccination policies and the updating of pneumococcal vaccines.

METHODS

We conducted a systematic review and random-effects meta-analysis to determine the proportion of community-acquired pneumonia (CAP) in people ≥50 years due to pneumococcus and the proportion caused by pneumococcal vaccine serotypes. We searched MEDLINE, EMBASE and PubMed from 1 January 1990 to 30 March 2021. Heterogeneity was explored by subgroup analysis according to a) patient group (stratified versus age) and depth of testing, b) detection/serotyping method, and c) continent. The protocol is registered with PROSPERO (CRD42020192002).

FINDINGS

Twenty-eight studies were included (34,216 patients). In the period 1-5 years after introduction of childhood PCV10/13 immunisation, 18% of CAP cases (95% CI 13-24%) were attributable to pneumococcus, with 49% (43-54%) of pneumococcal CAP due to PCV13 serotypes. The estimated proportion of pneumococcal CAP was highest in one study that used 24-valent serotype-specific urinary-antigen detection (ss-UAD)(30% [28-31%]), followed by studies based on diagnostic serology (28% [24-33%]), PCR (26% [15-37%]), ss-UAD14 (17% [13-22%]), and culture alone (14% [10-19%]). A higher estimate was observed in Europe (26% [21-30%] than North America (11% [9-12%](p<0·001). PCV13-serotype estimates were also influenced by serotyping methods.

INTERPRETATION

Non-invasive pneumococcal CAP and vaccine-type pneumococcal CAP remains a burden in older adults despite widespread introduction of pneumococcal infant immunisation. Studies heavily reliant on ss-UADs restricted to vaccine-type serotypes may overestimate the proportion of potentially vaccine-preventable pneumococcal pneumonia. Sero-epidemiological data from low-income countries are lacking.

Evaluation of the indirect impact of the 10-valent pneumococcal Haemophilus influenzae protein D conjugate vaccine in a cluster-randomised trial

Background

In the nation-wide double-blind cluster-randomised Finnish Invasive Pneumococcal disease trial (FinIP, ClinicalTrials.gov NCT00861380, NCT00839254), we assessed the indirect impact of the 10-valent pneumococcal Haemophilus influenzae protein D conjugate vaccine (PHiD-CV10) against five pneumococcal disease syndromes.

Methods

Children 6 weeks to 18 months received PHiD-CV10 in 48 clusters or hepatitis B/A-vaccine as control in 24 clusters according to infant 3+1/2+1 or catch-up schedules in years 2009―2011. Outcome data were collected from national health registers and included laboratory-confirmed and clinically suspected invasive pneumococcal disease (IPD), hospital-diagnosed pneumonia, tympanostomy tube placements (TTP) and outpatient antimicrobial prescriptions. Incidence rates in the unvaccinated population in years 2010―2015 were compared between PHiD-CV10 and control clusters in age groups <5 and ≥5 years (5―7 years for TTP and outpatient antimicrobial prescriptions), and in infants <3 months. PHiD-CV10 was introduced into the Finnish National Vaccination Programme (PCV-NVP) for 3-month-old infants without catch-up in 9/2010.

Results

From 2/2009 to 10/2010, 45398 children were enrolled. Vaccination coverage varied from 29 to 61% in PHiD-CV10 clusters. We detected no clear differences in the incidence rates between the unvaccinated cohorts of the treatment arms, except in single years. For example, the rates of vaccine-type IPD, non-laboratory-confirmed IPD and empyema were lower in PHiD-CV10 clusters compared to control clusters in 2012, 2015 and 2011, respectively, in the age-group ≥5 years.

Conclusions

This is the first report from a clinical trial evaluating the indirect impact of a PCV against clinical outcomes in an unvaccinated population. We did not observe consistent indirect effects in the PHiD-CV10 clusters compared to the control clusters. We consider that the sub-optimal trial vaccination coverage did not allow the development of detectable indirect effects and that the supervening PCV-NVP significantly diminished the differences in PHiD-CV10 vaccination coverage between the treatment arms.

Pivotal Phase 3 Randomized Clinical Trial of the Safety, Tolerability, and Immunogenicity of 20-Valent Pneumococcal Conjugate Vaccine in Adults 18 Years and Older

BACKGROUND

Pneumococcal conjugate vaccines (PCVs) have significantly reduced pneumococcal disease, but disease from non-PCV serotypes remains. Safety, tolerability, and immunogenicity of a 20-valent PCV (PCV20) were evaluated.

METHODS

This pivotal phase 3, randomized, double-blind study enrolled adults into 3 age groups (≥60, 50-59, 18-49 years) at US and Swedish sites. Participants were randomized to receive one PCV20 or PCV13 dose. After 1 month, participants ≥60 years also received one dose of saline or 23-valent polysaccharide vaccine (PPSV23). Safety assessments included local reactions, systemic events, adverse events, serious adverse events, and newly diagnosed chronic medical conditions. Opsonophagocytic activity (OPA) geometric mean titers (GMTs) 1 month after PCV20 were compared to 13 matched serotypes after PCV13 and to 7 additional serotypes after PPSV23 in participants ≥60 years; noninferiority was declared if lower bound of the 2-sided 95% CI for OPA GMT ratio (PCV20/saline:PCV13/PPSV23 group) was >0.5. PCV20-elicited immune responses in younger participants were also bridged to those in 60-64-year-olds.

RESULTS

Severity and frequency of prompted local reactions and systemic events were similar after PCV20 or PCV13; no safety concerns were identified. Primary immunogenicity objectives were met, with immune responses after PCV20 noninferior to 13 matched serotypes after PCV13 and to 6 additional PPSV23 serotypes in participants ≥60 years; serotype 8 missed the statistical noninferiority criterion. PCV20 induced robust responses to all 20 vaccine serotypes across age groups.

CONCLUSIONS

PCV20 was safe and well tolerated, with comparable immunogenicity to PCV13/PPSV23. PCV20 is anticipated to expand protection against pneumococcal disease in adults.

A trial to evaluate the safety and immunogenicity of a 20-valent pneumococcal conjugate vaccine in populations of adults ≥65 years of age with different prior pneumococcal vaccination

INTRODUCTION

A 20-valent pneumococcal conjugate vaccine, PCV20, was developed to expand protection against vaccine-preventable pneumococcal disease. PCV20 contains the components of the 13-valent pneumococcal conjugate vaccine, PCV13, and includes capsular polysaccharide conjugates for 7 additional serotypes. Thus, PCV20 may cover those additional serotypes in individuals previously vaccinated with PCV13 or provide benefits of immunization with a conjugate vaccine to individuals previously immunized with a pneumococcal polysaccharide vaccine. This study described the safety and immunogenicity of PCV20 in adults ≥65 years of age with prior pneumococcal vaccination.

METHODS

This phase 3, multicenter, randomized, open-label study was conducted in the United States and Sweden. Adults ≥65 years of age were enrolled into 1 of 3 cohorts based on their prior pneumococcal vaccination history (23-valent pneumococcal polysaccharide vaccine [PPSV23], PCV13, or both PCV13 and PPSV23). Participants were randomized 2:1 within their cohort to receive a single dose of PCV20 or PCV13 in those with prior PPSV23 only, and PCV20 or PPSV23 in those with prior PCV13 only; all participants with prior PCV13 and PPSV23 received PCV20. Safety was assessed by prompted local reactions within 10 days, systemic events within 7 days, adverse events (AEs) within 1 month, and serious AEs (SAEs) and newly diagnosed chronic medical conditions (NDCMCs) within 6 months after vaccination. Immune responses 1 month after PCV20 were assessed.

RESULTS

The percentages of participants reporting local reactions, systemic events, and AEs after PCV20 administration were similar across cohorts and comparable with the PCV13 and PPSV23 control groups. SAE and NDCMC rates were low in all groups. Robust immune responses, including opsonophagocytic antibody responses, to the 20 vaccine serotypes were observed 1 month after PCV20 regardless of prior pneumococcal vaccination.

CONCLUSIONS

PCV20 was well tolerated and immunogenic in adults ≥65 years of age previously vaccinated with different pneumococcal vaccine regimens. Clinicaltrials.gov NCT03835975.

Comparative characteristics of the background and blood test findings in adults with pneumococcal pneumonia and invasive pneumococcal disease: A retrospective study

INTRODUCTION

Invasive pneumococcal disease (IPD) is often fatal, requiring prompt diagnosis and treatment. To evaluate the factors associated with IPD in adults, we retrospectively investigated its characteristics compared to pneumococcal pneumonia without confirmation of invasion (PP).

METHODS

Patients >18 years with PP (n = 79) and IPD (n = 53) from whom Streptococcus pneumoniae was isolated were enrolled from two hospitals between 2011 and 2017. Clinical backgrounds, blood test results at admission, initial antimicrobials administered, isolate serotypes, and outcomes were compared between the PP and IPD groups.

RESULTS

Patients with IPD exhibited higher mortality (28.3%) than those with PP (2.5%) (p<0.001), regardless of the type of antimicrobials first administered. The majority (80.0%) of fatal cases of IPD were due to vaccine serotypes. Almost all patients with PP (97.4%) and IPD (88.7%) had underlying disease. C-reactive protein (CRP) ≥17.0 mg/dL (odds ratio [OR], 7.1; 95% CI, 2.7-19.0; p<0.001), white blood cell counts <11.0 × 10³/μL (OR, 3.2; 95% CI, 1.3-8.4; p = 0.016), and platelet (PLT) counts <16.2 × 10⁴/μL (OR, 2.8; 95% CI, 1.1-7.4; p = 0.036) were significantly more common in IPD. Moreover, 89.5% of cases with both CRP ≥23.8 mg/dL and PLT <18.5 × 10⁴/μL were diagnosed with IPD.

CONCLUSION

Laboratory blood test findings at admission, particularly high CRP and low PLT values, are useful early indicators of IPD in adults. These results could be used to initiate rapid and intensive treatment and improve prognosis.

Nasopharyngeal Carriage in Children After the Introduction of Generalized Infant Pneumococcal Conjugate Vaccine Immunization in Germany

Epidemiological data on nasopharyngeal (NP) bacterial carriage in children in Germany are scarce. We prospectively characterized NP colonization to evaluate the impact of pneumococcal immunization. We longitudinally collected NP swabs from 2-month-old infants (visit 1; V1) at eight representative pediatric offices 10/2008-06/2009. The second swabs were taken at age 9–12 months (V2); the third swab was taken 3–6 months after the booster vaccination at age 17–19 months (V3), and the fourth swab (V4) at age 59–61 months. Samples were broth enriched, cultured for bacteria, and isolates were serotyped. Demographic risk factors for colonization were evaluated. Among 242 vaccinees, bacterial NP carriage increased with age [from 27.2% (V1) to 70.1% (V4)]; leading isolates were S. pneumoniae, H. influenzae, M. catarrhalis, and S. pyogenes. Overall pneumococcal carriage increased [14.7% (V1), 31.5% (V2), 34.8% (V3), 42.2% (V4)], being even greater among day-care attendees. Serotype distribution changed during the study period, with vaccine serotypes declining. At visit 4, 10-valent pneumococcal conjugate vaccine (PCV10) serotypes were no longer among the NP flora, while some serotypes unique to 13-valent pneumococcal conjugate vaccine (PCV13; 3 and 19A) were found. In Germany, universal infant PCV immunization was associated with an almost complete eradication of PCV-serotypes and concomitant increase of non-PCV-serotypes, mainly 11A, 22F, and 23A.

Paediatric pneumonia in high-income countries: Defining and recognising cases at increased risk of severe disease

World Health Organisation definitions of pneumonia severity are routinely used in research. In high income health care settings with high rates of pneumococcal vaccination and low rates of mortality, malnutrition and HIV infection, these definitions are less applicable. National guidelines from leading thoracic and infectious disease societies describe 'severe pneumonia' according to criteria derived from expert consensus rather than a robust evidence base. Contemporary cohort studies have used clinical outcomes such as intensive care therapy or invasive procedures for complicated pneumonia, to define severe disease. Describing severe pneumonia in such clinically relevant terms facilitates the identification of risk factors associated with worsened disease and the subsequently increased morbidity, and need for tertiary level care. The early recognition of children at higher risk of severe pneumonia informs site of care decisions, antibiotic treatment decisions as well as guiding appropriate investigations. Younger age, malnutrition, comorbidities, tachypnoea, and hypoxia have been identified as important associations with 'severe pneumonia' by WHO definition. Most studies have been performed in low-middle income countries and whilst they provide some insight into those at risk of mortality or treatment failure, their generalisability to the high-income setting is limited. There is a need to determine more precise definitions and criteria for severe disease in well-resourced settings and to validate factors associated with intensive care admission or invasive procedures to enhance the early recognition of those at risk.

A phase 3, randomized, double-blind study to evaluate the immunogenicity and safety of 3 lots of 20-valent pneumococcal conjugate vaccine in pneumococcal vaccine-naive adults 18 through 49 years of age

INTRODUCTION

Introduction of pneumococcal conjugate vaccines (PCVs), including the 13-valent PCV (PCV13), has considerably reduced pneumococcal disease burden. However, additional serotypes not in PCV13 continue to present a substantial disease burden. The 20-valent PCV (PCV20) was developed to expand protection against pneumococcal disease beyond PCV13. As part of the phase 3 clinical development program, the current study assessed consistency of immune responses across 3 lots of PCV20 and described the safety profile of PCV20.

METHODS

This phase 3, randomized, multicenter, double-blind study of pneumococcal vaccine-naive adults 18-49 years of age randomized 1710 participants in a 2:2:2:1 ratio to receive 1 of 3 lots of PCV20 or PCV13. Immunogenicity was assessed through serotype-specific opsonophagocytic activity (OPA) titers before and approximately 1 month (28-42 days) after vaccination. Reported local reactions within 10 days, systemic events within 7 days, adverse events (AEs) within 30 days, and serious AEs (SAEs) and newly diagnosed chronic medical conditions (NDCMCs) within 6 months after vaccination were evaluated.

RESULTS

Equivalence in immune responses (OPA geometric mean titers) for all 20 vaccine serotypes was demonstrated across the 3 PCV20 lots. Robust responses, assessed by OPA geometric mean fold rises, percentage of participants achieving ≥4-fold rises, and percentage of participants with OPA titers ≥lower limit of quantitation, were observed after PCV20. Reported rates of local reactions, systemic events, and AEs were similar between the pooled PCV20 lots and PCV13; most events were mild or moderate. Reported rates of SAEs and NDCMCs were low and similar between the PCV20 and PCV13 groups.

CONCLUSIONS

Three different lots of PCV20 demonstrated robust and consistent immunogenicity. The safety and tolerability of PCV20 was acceptable and similar to that of PCV13. (Clinicaltrials.gov: NCT03828617).

Structural, Genetic, and Serological Elucidation of Streptococcus pneumoniae Serogroup 24 Serotypes: Discovery of a New Serotype, 24C, with a Variable Capsule Structure

Pneumococcal capsules are important in pneumococcal pathogenesis and vaccine development. Although conjugate vaccines have brought about a significant reduction in invasive pneumococcal disease (IPD) caused by vaccine serotypes, the relative serotype prevalence has shifted with the dramatic emergence of serotype 24F in some countries. Here, we describe 14 isolates (13 IPD and 1 non-IPD) expressing a new capsule type, 24C, which resembles 24F but has a novel serological profile. We also describe the antigenic, biochemical, and genetic basis of 24F and 24C and the related serotypes 24A and 24B. Structural studies show that 24B, 24C, and 24F have identical polysaccharide backbones [β-Ribf-(1→4)-α-Rhap-(1→3)-β-GlcpNAc-(1→4)-β-Rhap-(1→4)-β-Glcp] but with different side chains, as follows: 24F has arabinitol-phosphate and 24B has ribitol-phosphate. 24C has a mixture of 24F and 24B repeating units, with the ratio of ribitol to arabinitol being strain dependent. In contrast, the 24A capsule has a backbone without β-Ribf but with arabinitol-phosphate and phosphocholine side chains. These structures indicate that factor-sera 24d and 24e recognize arabinitol and ribitol, respectively, which explains the serology of serogroup 24, including those of 24C. The structures can be genetically described by the bispecificity of wcxG, which is capable of transferring arabinitol or ribitol when arabinitol is limiting. Arabinitol is likely not produced in 24B but is produced in reduced amounts in 24C due to various mutations in abpA or abpB genes. Our findings demonstrate how pneumococci modulate their capsule structure and immunologic properties with small genetic changes, thereby evading host immune responses. Our findings also suggest a potential for new capsule types within serogroup 24.

Immunogenicity of PCV24, an expanded pneumococcal conjugate vaccine, in adult monkeys and protection in mice

Invasive pneumococcal disease (IPD) is responsible for serious illnesses such as bacteremia, sepsis, meningitis, and pneumonia in young children, older adults, and persons with immunocompromising conditions and often leads to death. Although the most recent pneumococcal conjugate vaccines (PCVs) have been designed to target serotypes identified as the primary causative agents of IPD, the epidemiological landscape continues to change stressing the need to develop new PCVs. We have developed an investigational 24-valent PCV (PCV24) including serotypes 1, 2, 3, 4, 5, 6A, 6B, 7F, 8, 9N, 9V, 10A, 11A, 12F, 14, 15B, 17F, 18C, 19A, 19F, 20, 22F, 23F, and 33F all conjugated to CRM197 and evaluated this vaccine in adult monkeys. PCV24 was shown to be immunogenic and induced functional antibody for all vaccine serotypes. Of the serotypes common to PCV13 and V114 (PCV15), PCV24 had a similar immunogenic response with the exceptions of 23F which had higher IgG GMCs for PCV13 and V114, and 7F which had higher GMCs for PCV13. Functional antibody responses were similar for the serotypes in common between PCV24, PCV13 and V114 vaccines, with the exception of serotype 7F which was greater for PCV13. Overall, this study shows that PCV24 provided similar immunogenicity as the lower valent vaccines in adult monkeys with no apparent serotype interference. In addition, PCV24 also provided protection against pneumococcal infection in a mouse challenge model.

Long-term population effects of infant 10-valent pneumococcal conjugate vaccination on pneumococcal meningitis in Finland

BACKGROUND

No previous studies have reported long-term follow-up of ten-valent pneumococcal conjugate vaccine (PCV10) program impact on pneumococcal meningitis (PM). We assessed the effects of infant PCV10 program on PM incidence, mortality and serotype distribution in children and adults during 7 years after introduction.

METHODS

We conducted a population-based observational study. A case of PM was defined as isolation of Streptococcus pneumoniae from cerebrospinal fluid or, a patient with S. pneumoniae isolated from blood and an ICD-10 hospital discharge diagnosis of bacterial meningitis within 30 days before or after positive culture date.We compared age- and serotype-specific incidence and associated 30-day mortality rates in 2011-2017 (PCV10 period) with those in 2004-2010 (pre-PCV10 baseline) by using Poisson regression models. Absolute rate differences and 95% confidence intervals (CIs) were calculated from the parameter estimates by using delta method.

RESULTS

During the PCV10 period, the overall incidence of PCV10 serotype meningitis decreased by 68% (95%CI 57%-77%), and the overall PM incidence by 27% (95%CI: 12%-39%). In age groups 0-4, 50-64, and ≥ 18 years, the overall PM incidence was reduced by 64%, 34% and 19%, respectively. In adults ≥ 65 years of age, a 69% reduction in PCV10 serotypes was offset by 157% (56%-342%) increase in non-PCV10 serotypes. The overall PM-related mortality rate decreased by 42% (95%CI 4%-65%). Overall case fatality proportion (CFP) was 16% in pre-PCV10 period and 12% in PCV10 period (p = 0.41); among persons 50-64 years the CFP decreased from 25% to 10% (p = 0.04).

CONCLUSIONS

We observed substantial impact and herd protection for vaccine-serotype PM and associated mortality after infant PCV10 introduction. However, in older adults ≥ 65 years of age, PM burden remains unchanged due to serotype replacement.

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.

Multi-Valent Protein Hybrid Pneumococcal Vaccines: A Strategy for the Next Generation of Vaccines

Streptococcus pneumoniae (Spn) is a bacterial pathogen known to colonize the upper respiratory tract and cause serious opportunistic diseases such as pneumonia, bacteremia, sepsis and meningitis. As a consequence, millions of attributable deaths occur annually, especially among infants, the elderly and immunocompromised individuals. Although current vaccines, composed of purified pneumococcal polysaccharide in free form or conjugated to a protein carrier, are widely used and have been demonstrated to be effective in target groups, Spn has continued to colonize and cause life-threatening disease in susceptible populations. This lack of broad protection highlights the necessity of improving upon the current "gold standard" pneumococcal vaccines to increase protection both by decreasing colonization and reducing the incidence of sterile-site infections. Over the past century, most of the pneumococcal proteins that play an essential role in colonization and pathogenesis have been identified and characterized. Some of these proteins have the potential to serve as antigens in a multi-valent protein vaccine that confers capsule independent protection. This review seeks to summarize the benefits and limitations of the currently employed vaccine strategies, describes how leading candidate proteins contribute to pneumococcal disease development, and discusses the potential of these proteins as protective antigens-including as a hybrid construct.

Impact of pneumococcal conjugate vaccine on invasive pneumococcal disease in children under 5 years of age in the Czech Republic

Introduction

The aim of this study is to analyse the impact of vaccination of infants with pneumococcal conjugate vaccine (PCV) on the incidence of invasive pneumococcal disease (IPD) in children under 5 years of age in the Czech Republic.

Material and methods

The present study includes all IPD cases reported in children aged 0–4 years within the surveillance program in 2007–2017. The impact of PCV is analysed for five categories of IPD: cases caused by all serotypes, cases caused by PCV7 serotypes (4, 6B, 9V, 14, 18C, 19F, and 23F), cases caused by three additional PCV10 serotypes (1, 5, and 7F), cases caused by three additional PCV13 serotypes (3, 6A, and 19A), and cases caused by non-PCV serotypes. To assess the impact of PCV, the study period was divided into the pre-vaccination period 2007–2008 and post-vaccination period 2009–2017, which was divided into three three-year parts: 2009–2011, 2012–2014, and 2015–2017. Analysis of differences between periods was based on the Poisson regression model where the population numbers were handled as an offset.

Results

The annual incidence of IPD in children under 5 years of age caused by all serotypes has had a downward trend since 2007: it dropped from 8.52/100 000 in 2007 to 2.67/100 000 in 2017, with slight increases in 2010 and 2013. All three post-vaccination periods show significantly lower (p<0.001) incidences in comparison to the pre-vaccination period, but they do not statistically significantly differ from each other.

Conclusions

IPD surveillance data in the Czech Republic show that after the introduction of PCV vaccination of infants, there has been a significant decrease in the IPD incidence of children under 5 years of age. Continued IPD surveillance is essential to monitor for possible post-vaccination serotype replacement.

Health and economic burden of invasive pneumococcal disease associated with 15-valent pneumococcal conjugate vaccine serotypes in children across eight European countries

AIMS

V114, a 15-valent pneumococcal conjugate vaccine (PCV15) currently approved in adults in the US, contains the 13 S. pneumoniae serotypes in PCV13 and two additional serotypes, 22 F and 33 F, which are important contributors to residual PD. This study quantified the health and economic burden of pediatric invasive pneumococcal disease (IPD) associated with V114 serotypes in eight countries in Europe.

MATERIALS AND METHODS

A Markov model estimated V114-type IPD cases and costs in hypothetical unvaccinated birth cohorts from Denmark, France, Germany, Italy, Norway, Spain, Switzerland, and the UK over 20 years. Inputs were obtained from published literature. IPD cases and costs were calculated for three time periods using time-specific epidemiological data: (a) pre-PCV7; (b) pre-PCV13; and (c) post-PCV13. Costs were estimated from a societal perspective (2018 Euros) and discounted at 3%.

RESULTS

The model estimated that 4,649 IPD cases in the pre-PCV7 period, 3,248 cases in the pre-PCV13 period, and 958 cases in the post-PCV13 period were attributable to V114 serotypes. Total discounted costs associated with V114 serotypes were €109.1 million (pre-PCV7 period), €65.7 million (pre-PCV13 period), and €18.7 million (post-PCV13 period).

LIMITATIONS

Post-meningitis sequelae, acute otitis media, and non-bacteremic pneumonia were not considered. Direct non-medical costs were not included. Conclusions on effectiveness of V114 or added value over existing infant vaccination programs cannot be drawn.

CONCLUSIONS

IPD cases and costs were estimated in hypothetical birth cohorts in eight European countries followed for 20 years during three time periods. Serotypes included in V114 were associated with significant morbidity and costs in pre-PCV7, pre-PCV13, and post-PCV13 periods. Future pediatric pneumococcal vaccines should maintain protection against serotypes in licensed vaccines while extending coverage to additional serotypes to ensure reductions in IPD burden are maintained.

Serotype distribution and antimicrobial susceptibility of Streptococcus pneumoniae associated with invasive pneumococcal disease among adults in Japan

OBJECTIVES

This study evaluated the serotype distribution and antimicrobial susceptibility of Streptococcus pneumoniae isolates from adults (aged ≥20 years) with invasive pneumococcal disease (IPD) in Japan.

METHODS

This prospective observational study was conducted in 49 participating Japanese hospitals. S. pneumoniae isolates were serotyped and tested for antimicrobial susceptibility at a central laboratory. Information regarding patient characteristics, underlying disease, IPD clinical syndromes, and treatment was collected through medical chart review.

RESULTS

The final analysis included 177 patients enrolled from 45 hospitals between September 2016 and April 2018 (bacteraemic pneumonia, 110; bacteraemia without identified focus, 29; meningitis, 19). Most patients (70.1%) were aged ≥65 years and most had underlying disease (79.1%). The proportion of isolates from serotypes contained in the pneumococcal polysaccharide vaccine (PPV) 23 was 61.0%, while those in the pneumococcal conjugate vaccine (PCV) 7 and PCV13 were 2.8% and 28.2%, respectively. Non-vaccine serotypes accounted for 37.9% of all isolates and 50.8% of isolates from immunosuppressed patients. Serotype 12F was the most common vaccine serotype, followed by serotype 3.

CONCLUSIONS

The continued disease burden of IPD in adults in Japan warrants improved vaccination rates and development of next-generation vaccines that include serotypes not currently covered.

CLINICAL TRIAL REGISTRATION

Clinical trial summary registration number 160,822,918,146; JapicCTI-163352.

Impact of the 13-Valent Pneumococcal Conjugate Vaccine Among Adults: A Systematic Review and Meta-analysis

BACKGROUND

A notable reduction of the pneumococcal disease burden among adults was observed after the introduction of a 7-valent pneumococcal conjugate vaccine (PCV7) in childhood immunization programs. In 2010, a 13-valent pneumococcal conjugate vaccine (PCV13) replaced PCV7 in many jurisdictions; a comparative assessment of PCV13's impact was missing. Our objective was to summarize the available data and assess the change in the incidence of invasive pneumococcal disease (IPD) in adults after the introduction of PCV13 in childhood immunization programs.

METHODS

We conducted a systematic literature search from January 1946 to May 2017 of randomized, controlled trials and observational studies OBS reporting the incidence of IPD, non-invasive pneumococcal disease, hospitalizations, and mortality in adults for the periods before and after the introduction of PCV13. Incidence rate ratios (IRRs) were pooled across studies using restricted, maximum-likelihood, random-effects models.

RESULTS

From 3306 records,we included 29 OBS studies and 2033961 cases. Significantly lower IPD rates were seen after PCV13 introduction in adults aged <65 years (IRR 0.78, 95% confidence interval [CI] 0.72-0.85) and those aged ≥65 years (IRR 0.86, 95% CI 0.81-0.91). Lower rates of IPD were seen with PCV7 (IRR 0.45, 95% CI 0.38-0.54) and PCV13 serotypes (IRR 0.60, 95% CI 0.54-0.68). A significantly higher IRR of 1.10 (95% CI 1.04-1.17) for non-vaccine serotypes was observed, especially among those aged 65 years and older (IRR 1.20, 95% CI 1.11-1.29).

CONCLUSIONS

PCV13 use in children had a moderate impact on reducing the overall and vaccine-type IPDs, but there was a significant increase in non-vaccine type IPDs among adults, especially in those over 65 years.

Genetic characteristics of piliated Streptococcus pneumoniae serotype 35B, increased after introduction of pneumococcal vaccines in Japan

INTRODUCTION

Streptococcus pneumoniae is a commensal bacterium of the human nasopharynx and a major causative pathogen of bacterial diseases worldwide. Pilus of S. pneumoniae is one of the virulence factors which enhance the adhesion to the host epitherial cells in the upper respiratory tract.

METHODS

We analyzed the serotype distribution and presence of pilus genes, rrgC and sipA, among 785 S. pneumoniae isolates from specimens of patients with invasive or non-invasive disease in a regional Japanese hospital between October 2014 and August 2018. We next performed multilocus sequence typing and penicillin-resistant genotyping for 86 isolates of serotype 35B.

RESULTS

Serotype 35B was the most frequent serotype which accounted for 11.0% of total isolates and had pilus genes at high rate (80.2%). Clonal complex (CC) 558 isolates accounted for 77.9% of serotype 35B and were highly positive for rrgC and gPRSP (98.5%). In contrast, all CC2755 isolates (19.8%) were rrgC-negative and gPISP.

CONCLUSIONS

Our results suggest that CC558 may assist the prevalence of serotype 35B after the introduction of vaccines, as that clone has pili as adhesins in addition to non-susceptibility against penicillin. These results may be useful information for development of optimal preventive strategies. Continuous studies on serotype distribution and virulence factors of S. pneumoniae are necessary.

In vitro and in vivo Evaluation of in silico Predicted Pneumococcal UDPG:PP Inhibitors

Pneumonia, of which Streptococcus pneumoniae is the most common causative agent, is considered one of the three top leading causes of death worldwide. As seen in other bacterial species, antimicrobial resistance is on the rise for this pathogen. Therefore, there is a pressing need for novel antimicrobial strategies to combat these infections. Recently, uridine diphosphate glucose pyrophosphorylase (UDPG:PP) has been put forward as a potential drug target worth investigating. Moreover, earlier research demonstrated that streptococci lacking a functional galU gene (encoding for UDPG:PP) were characterized by significantly reduced in vitro and in vivo virulence. Therefore, in this study we evaluated the anti-virulence activity of potential UDPG:PP inhibitors. They were selected in silico using a tailor-made streptococcal homology model, based on earlier listerial research. While the compounds didn’t affect bacterial growth, nor affected in vitro adhesion to and phagocytosis in macrophages, the amount of polysaccharide capsule was significantly reduced after co-incubation with these inhibitors. Moreover, co-incubation proved to have a positive effect on survival in an in vivo Galleria mellonella larval infection model. Therefore, rather than targeting bacterial survival directly, these compounds proved to have an effect on streptococcal virulence by lowering the amount of polysaccharide and thereby probably boosting recognition of this pathogen by the innate immune system. While the compounds need adaptation to broaden their activity to more streptococcal strains rather than being strain-specific, this study consolidates UDPG:PP as a potential novel drug target.

Case Studies and Literature Review of Pneumococcal Septic Arthritis in Adults

We saw an increase in this condition related to emergence of Streptococcus pneumoniae serotype 23B.

We conducted a retrospective study on all cases of pneumococcal septic arthritis (SA) in patients >18 years of age reported to the Picardie Regional Pneumococcal Network in France during 2005–2016. Among 1,062 cases of invasive pneumococcal disease, we observed 16 (1.5%) SA cases. Although SA is uncommon in adult patients, the prevalence of pneumococcal SA in the Picardie region increased from 0.69% during 2005–2010 to 2.47% during 2011–2016 after introduction of the pneumococcal 13-valent conjugate vaccine. We highlight the emergence of SA cases caused by the 23B serotype, which is not covered in the vaccine.

Serotype and clonal distribution dynamics of invasive pneumococcal strains after PCV13 introduction (2011-2016): Surveillance data from 23 sites in Catalonia, Spain

Background

The objective of this study is to describe incidence and shifts of serotype and clonal distribution of invasive Streptococcus pneumoniae strains in four different age groups (<5 years, 5–17 years, 18–64 years and >65 years) during a period of intermediate PCV13 vaccination coverage (2011–2016) in Catalonia, Spain.

Methods

We included all pneumococcal strains systematically sent to the Catalan support laboratory for molecular surveillance of invasive pneumococcal disease (IPD) located at Hospital Sant Joan de Deu, Barcelona. Two study periods were considered: 2011–13, early PCV13 vaccination period (EVP) and 2014–2016, late vaccination period (LVP).

Results

A total of 2142 strains were included in the study. Five years after intermediate introduction of PCV13 in our population, a significant decrease of overall incidence of IPD in children <5 years was observed (incidence rate ratio 0.5, 95% confidence interval 0.4–0.8). However, in seniors older than 65 years, a significant increase of overall incidence of IPD was observed (IRR 1.4, 95% CI 1.1–1.7). The contribution of PCV13 vaccine serotypes to IPD declined significantly in all age groups: from 59% to 38.1% in <5 years; 82.7% to 59% in 5–17 years, 47.8% to 34.1% in 18–64 years and 48.2% to 37% in >65 years. Results found when comparing both periods were consistent with IRRs observed year by year. In children <5 years, the three major serotypes detected were 1, 24F and 19A in EVP vs 24F, 14 and 10A in LVP. Among patients 5–17 years the first three serotypes were 1, 12F and 14 both in EVP and LVP. Among adults 18–64, the three major serotypes detected were 1, 12F and 8 vs 8, 12F and 3, respectively. Finally, in patients >65 years the most frequently isolated serotypes were 3, 19A and 7F vs 3, 14 and 12F, respectively. Regarding clonal complexes (CCs) expressing mainly PCV13 serotypes, significant decreases of the proportions of CC306, CC191 and CC320 were observed, while CC156 showed a significant increase. As for CCs expressing mostly non-PCV13 serotypes, significant increases in ST989, CC53 and CC404 were showed.

Conclusions

Despite low vaccine coverage in our setting a significant decrease of incidence of IPD was observed in children younger than 5 years. The modest indirect protection against vaccine serotypes causing IPD in elderly indicate the need for the inclusion of more serotypes in future high-valent PCV and vaccinating old adults should be considered.

Molecular detection and genotypic characterisation of Streptococcus pneumoniae isolated from children in Malaysia

Streptococcus pneumoniae (S. pneumoniae) is one of the main causative agents of pneumococcal diseases. To date, more than 90 distinct serotypes have been identified. Implementation of vaccines has caused a drastic reduction in vaccine-serotype pneumococcal diseases but increase in cases due to non-vaccine serotype has been observed in Malaysia. However, further investigation on different serotype incidence in Malaysia is needed and the rate of pneumococcal vaccination for new-born babies in Malaysia remains low. The recent emergence of drug-resistant S. pneumoniae (DRSP) has also been a global concern, especially penicillin resistance. This study determined the serotypes of S. pneumoniae strains (n = 95) isolated from nasopharyngeal specimens from children admitted to UMMC from 2013 to 2015. In accordance with previous studies, PCR result showed 40% of NT isolates were successfully typed as 3 less common serotypes, namely 9N/L, 17A, and 23B. The repetitive-element PCR (REP-PCR) result revealed genetic variations among the strains whereby five major clusters were observed at the similarity of 80% by clustering analysis based on fingerprint data. Penicillin-binding proteins (pbps) of selected isolates were studied by PCR and sequencing. Three strains with ≤19-mm diameter zone for Oxacillin Disc Diffusion (ODD) test previously were recorded to have mutation on all pbp1a, pbp2b, and pbp2x with MIC of 4 µg/ml, which were penicillin-intermediate resistance according to the CLSI breakpoints.

Pneumococcal conjugate serotype distribution and predominating role of serotype 3 in German adults with community-acquired pneumonia

INTRODUCTION

Implementation of the 7-valent pneumococcal conjugate vaccine (PCV7) in infant vaccination programs has substantially reduced the burden of PCV7 serotypes also in adult community-acquired pneumonia (CAP). Currently, it is unclear, if this extensive herd protection effect can be extrapolated to the additional 6 serotypes included in the 13-valent pneumococcal conjugate vaccine (PCV13), which replaced PCV7 in Germany in 2010.

OBJECTIVES

We investigated changing trends for PCV13 serotypes in adult CAP patients between three to seven years after implementation of PCV13 infant immunization in Germany.

METHODS

Between December 2012 and January 2017, urine samples from German adult patients with radiologically confirmed CAP were prospectively collected by the multi-center cohort study CAPNETZ and analyzed by the serotype-specific multiplex urinary antigen detection assay (SSUAD) allowing for the detection of PCV13 serotypes.

RESULTS

PCV13 serotypes were found in 59 of 796 (7.4%) patients with all-cause CAP, most prevalent was serotype 3 (30 of 59 patients, 50.8%). All patients with serotype 3-CAP were admitted to hospital and the majority required oxygen at admission (83.3% of patients with serotype 3-CAP versus 50.9% of patients with pneumococcal CAP by other serotypes, p = 0.005). Compared to SSUAD testing, conventional microbiological workup missed 27 of 30 (90.0%) serotype 3-CAP cases. We could not observe a time trend in the proportions of PCV13 serotypes and serotype 3 in all-cause CAP between 2013 and 2016 (OR trend per year 0.84, 95% CI 0.64-1.11 for PCV13 serotypes and OR trend per year 0.95, 95% CI 0.70-1.28 for serotype 3).

CONCLUSIONS

Conventional methods underestimate serotype 3-CAP that can cause severe disease. Changes in overall PCV13 coverage were not detected during the years 2013 to 2016, mostly driven by a high proportion of serotype 3.

Serotype evolution in Western Europe: perspectives on invasive pneumococcal diseases (IPD)

Introduction: Epidemiologic trends for IPD have evolved with the introduction of pneumococcal conjugate vaccines into childhood immunization programs. We document the ongoing impact of PCV programs in 15 Western European countries.Areas covered: Data were collected from relevant published observational studies and national surveillance websites from January 2010 through January 2018. In countries using PCV13, the proportion of IPD due to PCV13 serotypes declined significantly (from 60-78% to 8-26%) in children <5 years of age within 5-8 years following vaccine introduction. In countries using PCV10, a marked decrease in PCV10-serotype IPD was reported; however, the proportion of IPD due to PCV13 serotypes remained high at 58-64%, predominantly due to serotypes 19A and 3.Expert opinion: The prevalence of vaccine-type IPD in adults remained high; emerging non-vaccine serotypes such as 8, 12F, 22F, 33F, and 15B/C should be a focus of future vaccine development.

Limited indirect effects of an infant pneumococcal vaccination program in an aging population

BACKGROUND

A general recommendation for adult pneumococcal vaccination with 23-valent polysaccharide vaccine (PPV23) for adults 60 and older has been in place in Germany since 1998, but uptake has been low. Just over a decade after the implementation of an infant pneumococcal conjugate vaccine recommendation, we examined indirect protection effects on adult invasive pneumococcal disease (IPD) in Germany.

METHODS AND FINDINGS

Reported IPD cases decreased in children under two years of age from 11.09 per 100,000 in 2003-2006 to 5.94 per 100,000 in 2017/18, while in adult age groups, reported IPD cases rose across the board, most dramatically in adults 60 years of age and over, from 1.64 to 10.08 cases per 100,000. PCV13-type IPD represents 31% of all cases in this age group, the lion's share of which is due to the rapid increase of serotype 3 IPD, which, by itself, has reached 2.11 reported cases per 100,000 and makes up 21% of all IPD cases in this age group. The two vaccine formulations currently in development (PCV15 and PCV20) would increase current (PCV13) coverage by 8.5% points and 28.0% points in children, while in adults coverage would increase by 10.4% points and 21.9% points, respectively.

CONCLUSIONS

While original models predicted that indirect effects of childhood vaccination would suffice for adults, it seems that the herd protection effect has reached its limit, with vaccine serotypes 4, 19F, and 19A IPD persisting in adults after initial reductions, and serotype 3 IPD not showing any herd protection effect at all.

The impact of childhood pneumococcal vaccination on hospital admissions in England: a whole population observational study

Background

Pneumococcal infections are major causes of morbidity and mortality worldwide. We use routine hospital admissions data and time-series modelling analysis to estimate the impact of the seven and thirteen valent pneumococcal conjugate vaccines (PCV7 and PCV13) on hospital admissions due to pneumococcal disease in England.

Methods

Hospital admissions for pneumococcal meningitis, bacteraemia and pneumonia between January 1, 2003 and December 31, 2015 were identified from the national Hospital Episode Statistics database for all age groups in England. We model the impact of pneumococcal vaccination using interrupted time series analysis. Hospital admissions prior to vaccine introduction were extrapolated to predict the expected number of admissions in the absence of pneumococcal vaccines. Admissions avoided over time were estimated by comparing the fitted interrupted time series and the expected model for no vaccination in a Bayesian framework.

Results

Overall, there were 43,531 (95% credible interval (CrI): 36486–51,346) fewer hospital admissions due to bacteraemia, meningitis and pneumonia in England during the period from 2006 to 2015 than would have been expected if pneumococcal vaccines had not been implemented, with the majority of hospital admissions avoided due to pneumonia. Among young children reductions in meningitis were more common, while among adults reductions in pneumonia admissions were relatively more important, with no evidence for reduced bacteraemia and meningitis among older adults. We estimated that 981 (95% CrI: 391–2018), 749 (95% CrI: 295–1442) and 1464 (95% CrI: 793–2522) bacteraemia, meningitis and pneumonia related hospital admissions, respectively, were averted in children < 2 years of age.

Conclusions

Substantial reductions in hospital admissions for bacteraemia, meningitis and pneumonia in England were estimated after the introduction of childhood vaccination, with indirect effects being responsible for most of the hospital admissions avoided.

Electronic supplementary material

The online version of this article (10.1186/s12879-019-4119-8) contains supplementary material, which is available to authorized users.

Effects of Pneumococcal Conjugate Vaccine on Genotypic Penicillin Resistance and Serotype Changes, Japan, 2010-2017

To clarify year-to-year changes in capsular serotypes, resistance genotypes, and multilocus sequence types of Streptococcus pneumoniae, we compared isolates collected from patients with invasive pneumococcal disease before and after introductions of 7- and 13-valent pneumococcal conjugate vaccines (PCV7 and PVC13, respectively). From April 2010 through March 2017, we collected 2,856 isolates from children and adults throughout Japan. Proportions of PCV13 serotypes among children decreased from 89.0% in fiscal year 2010 to 12.1% in fiscal year 2016 and among adults from 74.1% to 36.2%. Although nonvaccine serotypes increased after introduction of PCV13, genotypic penicillin resistance decreased from 54.3% in 2010 to 11.2% in 2016 among children and from 32.4% to 15.5% among adults. However, genotypic penicillin resistance emerged in 9 nonvaccine serotypes, but not 15A and 35B. Multilocus sequence typing suggested that resistant strains among nonvaccine serotypes may have evolved from clonal complexes 156 and 81. A more broadly effective vaccine is needed.

Serotype and molecular diversity of nasopharyngeal Streptococcus pneumoniae isolates from children before and after vaccination with the ten-valent pneumococcal conjugate vaccine (PCV10) in Ethiopia

Background

Streptococcus pneumoniae is a major human pathogen, and nasopharyngeal colonization is the first step for transmission and pathogenesis of pneumococcal diseases. Ethiopia introduced the 10-valent pneumococcal conjugate vaccine (PCV10) in October 2011. Here we studied nasopharyngeal carriage rates of pneumococci in children and analyzed the serotype and genetic diversity of pneumococcal isolates before first dose and after completion of the vaccine.

Method

A longitudinal study was conducted from February 2013 to November 2016. Totally 789 infants were enrolled at the age of 6 weeks before first dose of PCV10 vaccination, 206 were re-sampled at the age of 9 months, and 201 at 2 years of age after the final dose of PCV10 at the age of 14 weeks. One hundred sixteen children were followed during all the three sampling periods. A total of 422 nasopharyngeal isolates were serotyped using gel diffusion and the Quellung reaction, 325 were typed with pulsed field gel electrophoresis (PFGE), and 12 were selected for multi locus sequence typing (MLST).

Results

Pneumococcal carriage rates at the age of 6 weeks, 9 months and 2 years of age were 26.6% (210/789), 56.8% (117/206) and 48.3% (97/201), respectively. Out of 116 children none of them carried the same strain during the three period and the carriage rate at the age of 6 weeks, 9 months and 2 years were 32.7% (38/116), 59.% (69/116) and 49.1% (57/116) respectively. Totally 59 pneumococcal serotypes were identified among 422 isolates. Serotype 6A (5.0%) dominated followed by 34 (4.5%), 10A (4.0%), 11A (4.0%), 19F (3.8%), 15B (3.8%), 23F (3.6%), and 15A (3.6%). The proportion of non-PCV10 serotypes among the isolates recovered at 6 weeks, 9 months and 2 years was 79.4, 88.9 and 89.7% respectively. Molecular typing of 325 isolates collected at 6 weeks and 9 months of age showed a high genetic diversity.

Conclusion

This study highlights the presence of very diverse serotypes in Ethiopia where non-vaccine serotypes were predominant. Completion of the PCV10 schedule was associated with an approximately 50% reduction of vaccine-type carriage and increase of non-vaccine types. PCV13 would potentially reduce vaccine-type carriage by further 10%.

Electronic supplementary material

The online version of this article (10.1186/s12879-019-4024-1) contains supplementary material, which is available to authorized users.

Regional variations in serotype distribution and vaccination status in children under six years of age with invasive pneumococcal disease in Germany

Overview

The protective effect of infant pneumococcal conjugate vaccine (PCV) recommendation can be seen in Germany as a whole and in smaller regional groups. Comparisons between population-normalized geographic regions of Germany show different serotype distributions after program implementation, particularly in non-vaccine serotypes. The prior distinct differences in serotype distribution in children between the former East and former West German federal states have vanished. Children under six remain a vulnerable group, but the occurrence of vaccine-type (VT) invasive pneumococcal disease (IPD) in children correctly vaccinated (using a three-dose primary series plus one booster dose) with PCV13 was low (9 out of 374 cases, 2.4%). However, only 18.4% of children in Germany with IPD were correctly vaccinated with PCV13 according to the recommended schedule. Continued surveillance and better schedule adherence are essential to definitively establish the most effective PCV administration schedule.

Vaccination effects

For all PCV products used in Germany (PCV7, PCV10, and PCV13), vaccination status was the most common statistically significant predictor of infection with a particular serotype: Unvaccinated children old enough to have received at least one dose of vaccine in the PCV7 group had significantly higher odds (OR: 6.84, 95%CI: 2.66–22.06, adjusted for per capita income and residence in the northeastern federal states) of contracting VT IPD. In the PCV10 group, VT IPD had an OR of 4.52 (95% CI: 1.60–15.62, adjusted for year of infection, median household size, and residence in the southern federal states) in unvaccinated children, and in the PCV13 group, unvaccinated children continued to have higher odds (OR: 6.21, 95%CI: 3.45–11.36, adjusted for year of infection, age of child, per capita income, residence in the southern federal states, and percentage of children using public daycare) of getting vaccine-type IPD. Being unvaccinated was the most frequent significant indicator for infection with vaccine-type serotypes for each analysis group, while geographic groupings showed more limited potential to predict serotype of infection in early childhood IPD in Germany.

Effect of childhood pneumococcal conjugate vaccination on invasive disease in older adults of 10 European countries: implications for adult vaccination

BACKGROUND

Pneumococcal conjugate vaccines (PCVs) have the potential to prevent pneumococcal disease through direct and indirect protection. This multicentre European study estimated the indirect effects of 5-year childhood PCV10 and/or PCV13 programmes on invasive pneumococcal disease (IPD) in older adults across 13 sites in 10 European countries, to support decision-making on pneumococcal vaccination policies.

METHODS

For each site we calculated IPD incidence rate ratios (IRR) in people aged ≥65 years by serotype for each PCV10/13 year (2011-2015) compared with 2009 (pre-PCV10/13). We calculated pooled IRR and 95% CI using random-effects meta-analysis and PCV10/13 effect as (1 - IRR)*100.

RESULTS

After five PCV10/13 years, the incidence of IPD caused by all types, PCV7 and additional PCV13 serotypes declined 9% (95% CI -4% to 19%), 77% (95% CI 67% to 84%) and 38% (95% CI 19% to 53%), respectively, while the incidence of non-PCV13 serotypes increased 63% (95% CI 39% to 91%). The incidence of serotypes included in PCV13 and not in PCV10 decreased 37% (95% CI 22% to 50%) in six PCV13 sites and increased by 50% (95% CI -8% to 146%) in the four sites using PCV10 (alone or with PCV13). In 2015, PCV13 serotypes represented 20-29% and 32-53% of IPD cases in PCV13 and PCV10 sites, respectively.

CONCLUSION

Overall IPD incidence in older adults decreased moderately after five childhood PCV10/13 years in 13 European sites. Large declines in PCV10/13 serotype IPD, due to the indirect effect of childhood vaccination, were countered by increases in non-PCV13 IPD, but these declines varied according to the childhood vaccine used. Decision-making on pneumococcal vaccination for older adults must consider the indirect effects of childhood PCV programmes. Sustained monitoring of IPD epidemiology is imperative.

Probiotics and carriage of Streptococcus pneumoniae serotypes in Danish children, a double-blind randomized controlled trial

This study examined the carriage of Streptococcus pneumoniae in healthy Danish children aged 8–19 months and assessed the effect of the probiotics Lactobacillus rhamnosus GG and Bifidobacterium animalis subsp lactis on the pneumococcal carriage during daycare enrolment. Potential risk factors of pneumococcal carriage were analysed and the carriage study was compared with registered invasive pneumococcal disease (IPD) data. This study is a part of the ProbiComp study, which was a double-blind, randomized controlled trial, including 290 children allocated to probiotics or placebo for 6 months and recruited during two autumn seasons (2014/2015). Pneumococci were identified by optochin sensitivity, bile solubility, α-hemolysis and/or capsular reaction. Serotyping was performed by latex agglutination kit and Quellung reaction. The carriage rate of S. pneumoniae was 26.0% at baseline and 67.4% at the end of intervention. No significant difference was observed between the placebo group and the probiotics group (p = 0.508). Children aged 8–19 months were carriers of non-pneumococcal vaccine serotypes causing IPD in children aged 0–4 years. However, serotypes causing most IPD cases in Danish elderly were either not found or found with low prevalence suggesting that children are not the main reservoir of those serotypes and other age groups need to be considered as carriers.

Gamma-irradiation-killed Streptococcus pneumoniae potently induces the expression of IL-6 and IL-8 in human bronchial epithelial cells

Streptococcus pneumoniae is a major respiratory pathogen that can cause pneumonia, meningitis, and otitis media. Although capsular polysaccharide-based vaccines are commercially available, there is a need for broad-spectrum, serotype-independent, and cost-effective vaccines. Recently, an intranasal vaccine formulated with gamma-irradiated nonencapsulated S. pneumoniae whole cells has been developed and its immunogenicity is under investigation. Since innate immunity influences the subsequent adaptive immunity, in the present study, we investigated the immunostimulatory activity of gamma-irradiated S. pneumoniae (r-SP) in the human bronchial epithelial cell-line, BEAS-2B, by comparing with heat-inactivated S. pneumoniae (h-SP) and formalin-inactivated S. pneumoniae (f-SP). r-SP potently induced interleukin (IL)-6 and IL-8 at both mRNA and protein levels in a dose- and time-dependent manner, whereas h-SP and f-SP poorly induced them. Of note, the mRNA levels of IL-6 and IL-8 were approximately two-fold higher when cells were stimulated with 3 × 10⁷ CFU/ml of r-SP for 3 h, while the protein levels of IL-6 and IL-8 were approximately five-fold higher after stimulation with 3 × 10⁷ CFU/ml of r-SP for 24 h. Furthermore, r-SP exhibited potent activation of Toll-like receptor 2 compared with h-SP or f-SP. The expression of IL-6 and IL-8 induced by r-SP was mediated through the activation of mitogen-activated protein kinases. Remarkably, when r-SP was further treated with heat or formalin, there was a decrease in the aforementioned activities. Taken together, we suggest that r-SP stimulates the human respiratory epithelial cells to produce the cytokines IL-6 and IL-8, which might influence the induction of adaptive immune responses.

Immunogenicity and safety of 11- and 12-valent pneumococcal non-typeable Haemophilus influenzae protein D-conjugate vaccines (11vPHiD-CV, 12vPHiD-CV) in infants: Results from a phase II, randomised, multicentre study

BACKGROUND

We assessed 2 investigational 11- and 12-valent vaccines, containing capsular polysaccharides of 10 serotypes as in the pneumococcal non-typeable Haemophilus influenzae protein D-conjugate vaccine (PHiD-CV) and CRM₁₉₇-conjugated capsular polysaccharides of serotypes 19A (11-valent) or 19A and 6A (12-valent).

METHODS

In this phase II, partially-blind, multicentre study (NCT01204658), healthy infants were randomised (1:1:1:1) to receive 11vPHiD-CV, 12vPHiD-CV, PHiD-CV, or 13-valent CRM₁₉₇-conjugate pneumococcal vaccine (PCV13), at 2, 3, and 4 (primary series), and 12-15 months of age (booster dose), co-administered with DTPa-HBV-IPV/Hib. Confirmatory objectives assessed non-inferiority of investigational vaccines to comparators (PHiD-CV for common serotypes; PCV13 for 19A and 6A), in terms of percentage of infants with pneumococcal antibody concentrations ≥0.2 μg/mL and antibody geometric mean concentrations, post-primary vaccination. Reactogenicity and safety were assessed.

RESULTS

951 children received ≥1 primary dose, 919 a booster dose. Pre-defined immunological non-inferiority criteria were met simultaneously for 9/11 11vPHiD-CV serotypes (all except 23F and 19A) and 10/12 12vPHiD-CV serotypes (all except 19A and 6A); thus, non-inferiority objectives were reached. For each PHiD-CV serotype, percentages of children with antibody concentrations ≥0.2 µg/mL were ≥96.7% post-primary (except 6B [≥75.2%] and 23F [≥81.1%]), and ≥98.1% post-booster vaccination. For each PHiD-CV serotype except serotype 1, ≥81.0% and ≥93.9% of children had opsonophagocytic activity titres ≥8, post-primary and booster vaccination. AEs incidence was similar across all groups. SAEs were reported for 117 children (29 in the 11vPHiD-CV group, 26 in the 12vPHiD-CV group, 38 in the PHiD-CV group and 24 in the PCV13 group); 4 SAEs were considered vaccination-related. No fatal events were recorded.

CONCLUSION

Addition of 19A and 6A CRM₁₉₇-conjugates did not alter immunogenicity of the PHiD-CV conjugates; for both investigational vaccines post-booster immune responses to 10 common serotypes appeared similar to those elicited by PHiD-CV. Safety and reactogenicity profiles of the investigational vaccines were comparable to PHiD-CV. Clinical trial registry: NCT01204658.

The changing epidemiology of invasive pneumococcal disease after PCV13 vaccination in a country with intermediate vaccination coverage

BACKGROUND

We studied the impact of 13-valent pneumococcal conjugate vaccine (PCV13) on the incidence of invasive pneumococcal disease (IPD) and serotype distribution in a region with intermediate levels of vaccination (around 64% in children aged <2 years).

METHODS

Surveillance data on IPD cases reported by microbiologists participating in the Microbiological Reporting System of Catalonia during 2006-2014 were analysed. We compared estimated incidence rate (IR) ratios for serotypes included in PCV7, PCV10non7, PCV13non10 and non-PCV13 between the PCV7 (2006-2009) and PCV13 periods (2010-2014). IR were corrected for missing serotypes according to year and age groups: <2 years, 2-4 years, 5-64 years and ≥65 years.

RESULTS

A total of 9338 IPD cases were reported. Overall IPD incidence declined by 26.2% (from 16.4 to 12.1) in the PCV13 period. The largest decrease was observed in children aged 2-4 years (44.5%, from 37.4 to 20.8). Pneumonia fell in all age groups with the largest reduction in children aged 2-4 years (49.3%) and <2 years (42%). PCV13 serotypes decreased significantly in all age groups, from 52% (31.6 to 15.1) in children aged 2-4 years to 35% (22.8 to 14.8) in adults aged ≥65 years. Non-PCV13 serotypes rose by 13% (14.8 to 16.8) in people aged ≥65 years.

CONCLUSIONS

In a region with intermediate vaccination coverage, the introduction of PCV13 has reduced the overall incidence of IPD, mainly due to the decrease in PCV13 serotypes in all age groups, suggesting herd immunity. Non-PCV13 serotypes have increased in adults aged ≥65 years, suggesting serotype replacement. Higher PCV13 vaccination coverage in children will further reduce IPD incidence in all age groups.

Serotype distribution of invasive Streptococcus pneumoniae in adults 65 years of age and over after the introduction of childhood 13-valent pneumococcal conjugate vaccination programs in Canada, 2010-2016

The 13-valent conjugate vaccine (PCV13) was recommended for childhood immunization programs in 2010 in Canada and has decreased the incidence of invasive pneumococcal disease (IPD) in children and changed the epidemiology of IPD in adults. This study investigated the epidemiology of IPD in adults 65 years of age and older in Canada. A total of 7282 invasive S. pneumoniae isolated from adults ≥65 years old were serotyped from 2010 to 2016 and antimicrobial susceptibility was performed on 2527 isolates. Serotyping was performed by Quellung reaction using commercial antisera and antimicrobial susceptibilities were determined by broth microdilution. PCV7 serotypes decreased non-significantly from 2010 to 2016 from 9.1% (n = 96) to 6.7% (n = 72) while the additional six PCV13 serotypes declined significantly from 39.5% (n = 418) to 18.6% (n = 201) (p < 0.05). The 23-valent pneumococcal polysaccharide vaccine (PPV23) and non-vaccine (NVT) serotypes increased from 26.3% (n = 278) to 36.2% (n = 393) (p < 0.05), and from 25.1% (n = 266) to 38.4% (n = 416) (p < 0.05), respectively. There were no significant changes in antimicrobial resistance rates from 2011 to 2016: 24.1% of the IPD from adults ≥65 years were resistant to clarithromycin (n = 609), 10.0% to doxycycline (n = 254), 11.8% to penicillin (n = 299), 5.2% to cefuroxime (n = 131), 6.6% to clindamycin (n = 168), 6.0% to trimethoprim-sulfamethoxazole (n = 152), and 0.5% (n = 12) to ceftriaxone. Although overall incidence of IPD in adults ≥65 years has remained relatively constant from 2010 to 2016, childhood PCV13 vaccination programs have been successful in indirectly reducing IPD caused by PCV13 serotypes in adults through herd immunity effects.

Development and characterization of a synthetic DNA, NUversa, to be used as a standard in quantitative polymerase chain reactions for molecular pneumococcal serotyping

Identification of Streptococcus pneumoniae and its more than 90 serotypes is routinely conducted by culture and Quellung reactions. Quantitative polymerase chain reactions (qPCRs) have been developed for molecular detection, including a pan-pneumococcus lytA assay, and assays targeting 79 serotypes. Reactions require genomic DNA from every target to prepare standards, which can be time consuming. In this study, we have developed a synthetic DNA molecule as a surrogate for genomic DNA and present new single-plex qPCR reactions to increase molecular detection to 94 pneumococcal serotypes. Specificity of these new reactions was confirmed with a limit of detection between 2 and 20 genome equivalents/reaction. A synthetic DNA (NUversa, ∼8.2 kb) was then engineered to contain all available qPCR targets for serotyping and lytA. NUversa was cloned into pUC57-Amp-modified to generate pNUversa (∼10.2 kb). Standards prepared from pNUversa and NUversa were compared against standards made out of genomic DNA. Linearity [NUversa (R² > 0.982); pNUversa (R² > 0.991)] and efficiency of qPCR reactions were similar to those utilizing chromosomal DNA (R² > 0.981). Quantification with plasmid pNUversa was affected, however, whereas quantification with synthetic NUversa was comparable to that of genomic DNA. Therefore, NUversa may be utilized as DNA standard in single-plex assays of the currently known 94 pneumococcal serotypes.

Economic evaluation of pneumococcal vaccines for adults aged over 50 years in Belgium

Streptococcus pneumoniae causes a high disease burden including pneumonia, meningitis and septicemia. Both a polysaccharide vaccine targeting 23 serotypes (PPV23) and a 13-valent conjugate vaccine (PCV13) are indicated for persons aged over 50 years. We developed and parameterized a static multi-cohort model to estimate the incremental cost-effectiveness and budget-impact of these vaccines at different uptake levels. Using three different vaccine efficacy scenarios regarding non-invasive pneumococcal pneumonia and extensive uni- and multivariate sensitivity analyses, we found a strong preference for PPV23 over PCV13 in all age groups at willingness to pay levels below €300 000 per quality adjusted life year (QALY). PPV23 vaccination would cost on average about €83 000, €60 000 and €52 000 per QALY gained in 50-64, 65-74 and 75-84 year olds, whereas for PCV13 this is about €171 000, €201 000 and €338 000, respectively. Strategies combining PPV23 and PCV13 vaccines were most effective but generally less cost-effective. When assuming a combination of increased duration of PCV13 protection, increased disease burden preventable by PCV13 and a 75% reduction of the PCV13 price, PCV13 could become more attractive in <75 year olds, but would remain less attractive than PPV23 from age 75 years onwards. These observations are independent of the assumption that PPV23 has 0% efficacy against non-invasive pneumococcal pneumonia. Pneumococcal vaccination would be most cost-effective in Belgium, when achieving high uptake with PPV23 in 75-84 year olds, as well as by negotiating a lower market-conform PPV23 price to improve uptake and cost-effectiveness.