Pneumococcal serotype distribution: A snapshot of recent data in pediatric and adult populations around the world

Pneumococcal carriage and serotype distribution in children with nephrotic syndrome

BACKGROUND

Patients with nephrotic syndrome (NS) are at a higher risk of developing invasive pneumococcal disease (IPD). Pneumococcal carriage studies are helpful tools for detecting potentially infectious serotypes and guiding immunization efforts. Pneumococcal nasopharyngeal colonization is common, and IPD can easily occur in an immunosuppressed state. Limited information is available regarding the frequency of pneumococcal carriage in individuals with NS. The aim of this study was to evaluate pneumococcal carriage and serotype distribution in children with NS.

METHODS

Pneumococcal carriage was detected by real-time PCR assays from nasopharyngeal swab samples from 98 children with NS, and 100 healthy controls. Isolates were serotyped by real-time PCR.

RESULTS

The pneumococcal carriage rate was 44.9% in children with NS. Regarding the recommendation about pneumococcal immunization in children with NS, the vaccination rate was low. Also, non-PCV13 serotypes have been detected in at least 25% of PCV13-vaccinated children. There is no statistically significant difference in total pneumococcal carriage rate, PCV13 serotype carriage rate, or non-PCV13 serotype carriage rate between children with NS and healthy controls (p > 0.05 for all).

CONCLUSIONS

The pneumococcal carriage rate was similar between children with NS and healthy controls. However, because children with NS have an increased risk for IPD, the serotype distribution of children with NS can demonstrate the improved protection offered by new pneumococcal vaccines. Regular monitoring for IPD is crucial for assessing the evolving sero-epidemiology of pneumococcal infections and evaluating the effectiveness of vaccines for children with NS.

Phase 3 Safety and Immunogenicity Study of a Three-dose Series of Twenty-valent Pneumococcal Conjugate Vaccine in Healthy Infants and Toddlers

BACKGROUND

Global pediatric immunization programs with pneumococcal conjugate vaccines (PCVs) have reduced vaccine-type pneumococcal disease, but a substantial disease burden of non-PCV serotypes remains.

METHODS

This phase 3, randomized (1:1), double-blind study evaluated safety and immunogenicity of 20-valent PCV (PCV20) relative to 13-valent PCV (PCV13) in healthy infants. Participants received 2 infant doses and a toddler dose of PCV20 or PCV13, with diphtheria-tetanus-acellular pertussis combination vaccine at all doses and measles, mumps, rubella and varicella vaccines at the toddler dose. Primary pneumococcal immunogenicity objectives were to demonstrate noninferiority (NI) of PCV20 to PCV13 for immunoglobulin G geometric mean concentrations after infant and toddler doses and percentages of participants with predefined serotype-specific immunoglobulin G concentrations after infant doses. Safety endpoints included local reactions, systemic events and adverse events.

RESULTS

Overall, 1204 participants were vaccinated (PCV20, n = 601; PCV13, n = 603). One month after the toddler dose, 19/20 serotypes met NI for immunoglobulin G geometric mean concentrations; serotype 6B narrowly missed NI [PCV20/PCV13 geometric mean ratio: 0.57 (2-sided 95% confidence interval: 0.48-0.67); NI criterion: lower 2-sided 95% confidence interval >0.5]. Sixteen/twenty serotypes met NI for ≥1 primary objective after 2 infant doses. PCV20 induced robust opsonophagocytic activity, and boosting responses were observed for all vaccine serotypes, including those missing statistical NI. The safety/tolerability profile of PCV20 was like that of PCV13.

CONCLUSIONS

PCV20 3-dose series in infants was safe and elicited robust immune responses. Based on these results and PCV13 experience, PCV20 3-dose series is expected to be protective for all 20 vaccine serotypes. NCT04546425.

Serotype epidemiology and antibiotic resistance of pneumococcal isolates colonizing infants in Botswana (2016-2019)

BACKGROUND

In 2012, Botswana introduced 13-valent pneumococcal conjugate vaccine (PCV-13) to its childhood immunization program in a 3+0 schedule, achieving coverage rates of above 90% by 2014. In other settings, PCV introduction has been followed by an increase in carriage or disease caused by non-vaccine serotypes, including some serotypes with a high prevalence of antibiotic resistance.

METHODS

We characterized the serotype epidemiology and antibiotic resistance of pneumococcal isolates cultured from nasopharyngeal samples collected from infants (≤12 months) in southeastern Botswana between 2016 and 2019. Capsular serotyping was performed using the Quellung reaction. E-tests were used to determine minimum inhibitory concentrations for common antibiotics.

RESULTS

We cultured 264 pneumococcal isolates from samples collected from 150 infants. At the time of sample collection, 81% of infants had received at least one dose of PCV-13 and 53% had completed the three-dose series. PCV-13 serotypes accounted for 27% of isolates, with the most prevalent vaccine serotypes being 19F (n = 20, 8%), 19A (n = 16, 6%), and 6A (n = 10, 4%). The most frequently identified non-vaccine serotypes were 23B (n = 29, 11%), 21 (n = 12, 5%), and 16F (n = 11, 4%). Only three (1%) pneumococcal isolates were resistant to amoxicillin; however, we observed an increasing prevalence of penicillin resistance using the meningitis breakpoint (2016: 41%, 2019: 71%; Cochran-Armitage test for trend, p = 0.0003) and non-susceptibility to trimethoprim-sulfamethoxazole (2016: 55%, 2019: 79%; p = 0.04). Three (1%) isolates were multi-drug resistant.

CONCLUSIONS

PCV-13 serotypes accounted for a substantial proportion of isolates colonizing infants in Botswana during a four-year period starting four years after vaccine introduction. A low prevalence of amoxicillin resistance supports its continued use as the first-line agent for non-meningeal pneumococcal infections. The observed increase in penicillin resistance at the meningitis breakpoint and the low prevalence of resistance to ceftriaxone supports use of third-generation cephalosporins for empirical treatment of suspected bacterial meningitis.

Cost-Effectiveness of 20-Valent Pneumococcal Conjugate Vaccine Among US Children with Underlying Medical Conditions

INTRODUCTION

A 20-valent pneumococcal conjugate vaccine (PCV20) was recently recommended for use among US children. We evaluated the cost-effectiveness of PCV20 among children aged 6 years with chronic medical conditions (CMC+) and children aged 6 years with immunocompromising conditions (IC) versus one and two doses of 23-valent pneumococcal polysaccharide vaccine (PPSV23), respectively.

METHODS

A probabilistic model was employed to depict 10-year risk of clinical outcomes and economic costs of pneumococcal disease, reduction in life years from premature death, and expected impact of vaccination among one cohort of children with CMC+ and IC aged 6 years. Vaccine uptake was assumed to be 20% for both PCV20 and PPSV23. Cost per quality-adjusted life year (QALY) gained was evaluated from the US societal and healthcare system perspectives; deterministic and probabilistic sensitivity analyses (DSA/PSA) were also conducted.

RESULTS

Among the 226,817 children with CMC+ aged 6 years in the US, use of PCV20 (in lieu of PPSV23) was projected to reduce the number cases of pneumococcal disease by 5203 cases, medical costs by US$8.7 million, and nonmedical costs by US$6.2 million. PCV20 was the dominant strategy versus PPSV23 from both the healthcare and societal perspectives. In the PSA, 99.9% of the 1000 simulations yielded a finding of dominance for PCV20. Findings in analyses of children with IC aged 6 years in the USA were comparable (i.e., PCV20 was the dominant vaccination strategy). Scenario analyses showed that increasing PCV20 uptake to 100% could potentially prevent > 22,000 additional cases of pneumococcal disease and further reduce medical and nonmedical costs by US$70.0 million among children with CMC+ and IC.

CONCLUSIONS

Use of PCV20 among young children with CMC+ and IC in the USA would reduce the clinical burden of pneumococcal disease and yield overall cost savings from both the US healthcare system and societal perspectives. Higher PCV20 uptake could further reduce the number of pneumococcal disease cases in this population.

Cost-effectiveness of 20-valent pneumococcal conjugate vaccine in US infants

BACKGROUND

As of June 2023, two pneumococcal conjugate vaccines, 20- (PCV20) and 15- (PCV15) valent formulations, are recommended for US infants under a 3 + 1 schedule. This study evaluated the health and economic impact of vaccinating US infants with a new expanded valency PCV20 formulation.

METHODS

A population-based, multi cohort, decision-analytic Markov model was developed to estimate the public health impact and cost-effectiveness of PCV20 from both societal and healthcare system perspectives over 10 years. Epidemiological data were based on published studies and unpublished Active Bacterial Core Surveillance System (ABCs) data. Vaccine effectiveness was based on PCV13 effectiveness and PCV7 efficacy studies. Indirect impact was based on observational studies. Costs and disutilities were based on published data. PCV20 was compared to both PCV13 and PCV15 in separate scenarios.

RESULTS

Replacing PCV13 with PCV20 in infants has the potential to avert over 55,000 invasive pneumococcal disease (IPD) cases, 2.5 million pneumonia cases, 5.4 million otitis media (OM) cases, and 19,000 deaths across all ages over a 10-year time horizon, corresponding to net gains of 515,000 life years and 271,000 QALYs. Acquisition costs of PCV20 were offset by monetary savings from averted cases resulting in net savings of $20.6 billion. The same trend was observed when comparing PCV20 versus PCV15, with a net gain of 146,000 QALYs and $9.9 billion in net savings. A large proportion of the avoided costs and cases were attributable to indirect effects in unvaccinated adults and elderly. From a health-care perspective, PCV20 was also the dominant strategy compared to both PCV13 and PCV15.

CONCLUSIONS

Infant vaccination with PCV20 is estimated to further reduce pneumococcal disease and associated healthcare system and societal costs compared to both PCV13 and PCV15.

Cost-effectiveness and impact on infections and associated antimicrobial resistance of 20-valent pneumococcal conjugate vaccine in US children previously immunized with PCV13

AIM

The US Food and Drug Administration approved the 20-valent pneumococcal conjugate vaccine (PCV20) to prevent pneumococcal disease. In the context of routine PCV20 vaccination, we evaluated the cost-effectiveness and public health and economic impact of a PCV20 catch-up program and estimated the number of antibiotic prescriptions and antibiotic-resistant infections averted.

MATERIALS AND METHODS

A population-based, multi-cohort, decision-analytic Markov model was developed using parameters consistent with previous PCV20 cost-effectiveness analyses. In the intervention arm, children aged 14-59 months who previously completed PCV13 vaccination received a supplemental dose of PCV20. In the comparator arm, no catch-up PCV20 dose was given. The direct and indirect benefits of vaccination were captured over a 10-year time horizon.

RESULTS

A PCV20 catch-up program would prevent 5,469 invasive pneumococcal disease cases, 50,286 hospitalized pneumonia cases, 218,240 outpatient pneumonia cases, 582,302 otitis media cases, and 1,800 deaths, representing a net gain of 30,014 life years and 55,583 quality-adjusted life years. Furthermore, 720,938 antibiotic prescriptions and 256,889 antibiotic-resistant infections would be averted. A catch-up program would result in cost savings of $800 million. These results were robust to sensitivity and scenario analyses.

CONCLUSIONS

A PCV20 catch-up program could prevent pneumococcal infections, antibiotic prescriptions, and antimicrobial-resistant infections and would be cost-saving in the US.

Serotype distribution of Streptococcus pneumoniae and pneumococcal vaccine coverage in adults in Turkey between 2015 and 2018

OBJECTIVE

To evaluate the serotype distribution and antibiotic resistance in pneumococcal infections in adults and to provide a perspective regarding serotype coverage of both current and future pneumococcal vaccines.

PATIENTS AND METHODS

This passive surveillance study was conducted with the Streptococcus pneumoniae strains isolated from the specimens of patients with pneumonia (materials isolated from bronchoalveolar lavage), bacteraemia, meningitis, pleuritis and peritonitis between 2015 and 2018. Serogrouping and serotyping were performed by latex particle agglutination and by conventional Quellung reaction using commercial type-specific antisera, respectively. The strains were analysed for penicillin, cefotaxime, erythromycin and moxifloxacin susceptibilities by E-test.

RESULTS

In the whole study group (410 samples from adults aged ≥18 years), the most frequent serotypes were 3 (14.1%), 19 F (12%) and 1 (9.3%). The vaccine coverage for PCV13, PCV15, PCV20 and PPV23 was 63.9%, 66.6%, 74.1% and 75.9%, respectively, in all isolates. Penicillin non-susceptibility in invasive pneumococcal disease (IPD) was 70.8% and 57.1% in the patients aged <65 and ≥65 years, respectively. About 21.1% and 4.3% of the patients with and without IPD had cefotaxime resistance. Non-susceptibility to erythromycin and moxifloxacin was 38.2% and 1.2%, respectively.

CONCLUSIONS

The results revealed that novel PCV vaccines may provide improved coverage as compared with the currently available vaccine, PCV13. The significant antibiotic resistance rates imply the need to extend the serotype coverage of the vaccines. Continuing the surveillance in pneumococcal diseases is critical to explore the serotype distribution and incidence changes of IPD cases in the population and to inform policy makers to make necessary improvements in the national immunization programmes.Key messagesThis multicentre study demonstrated the most recent serotype distribution and antibiotic resistance in adult population in Turkey.Shifting from PCV13 to novel conjugated vaccines will significantly increase the coverage.Continuing the surveillance in pneumococcal diseases is critical to explore the serotype distribution changes and the incidence of cases with invasive pneumococcal disease in the population.

Combinatorial multimer staining and spectral flow cytometry facilitate quantification and characterization of polysaccharide-specific B cell immunity

Bacterial capsular polysaccharides are important vaccine immunogens. However, the study of polysaccharide-specific immune responses has been hindered by technical restrictions. Here, we developed and validated a high-throughput method to analyse antigen-specific B cells using combinatorial staining with fluorescently-labelled capsular polysaccharide multimers. Concurrent staining of 25 cellular markers further enables the in-depth characterization of polysaccharide-specific cells. We used this assay to simultaneously analyse 14 Streptococcus pneumoniae or 5 Streptococcus agalactiae serotype-specific B cell populations. The phenotype of polysaccharide-specific B cells was associated with serotype specificity, vaccination history and donor population. For example, we observed a link between non-class switched (IgM+) memory B cells and vaccine-inefficient S. pneumoniae serotypes 1 and 3. Moreover, B cells had increased activation in donors from South Africa, which has high-incidence of S. agalactiae invasive disease, compared to Dutch donors. This assay allows for the characterization of heterogeneity in B cell immunity that may underlie immunization efficacy.

Evaluation of cross-protection between S. Pneumoniae serotypes 35B and 29 in a mouse model

Pneumococcal conjugate vaccines (PCVs) have reduced vaccine-type pneumococcal disease but in turn have also resulted in replacement with non-vaccine serotypes. One such serotype, 35B, a multidrug resistant type, has been associated with an increase in disease. Mice were immunized intramuscularly with monovalent pneumococcal polysaccharide 35B conjugated to CRM197 containing aluminum phosphate adjuvant on days 0, 14, and 28. Pneumococcal enzyme-linked immunosorbent assay, opsonophagocytic killing assays, and competition OPA were performed for STs 35B and 29 to measure serotype-specific binding and functional antibodies. On day 52, mice were intratracheally challenged with S. pneumoniae ST29 to evaluate cross-protection. 35B-CRM197 immunized mice had binding and functional antibodies to both PnPs 35B and 29. 35B-CRM197 immunized mice were 100% protected from IT challenge with S. pneumoniae ST29 as compared to 30% survival in the naïve group. Future vaccines containing polysaccharide 35B, such as the investigational 21-valent PCV, V116, may provide cross protection against the non-vaccine serotype 29 due to structural similarity.

Safety, tolerability, and immunogenicity of a 21-valent pneumococcal conjugate vaccine, V116, in healthy adults: phase 1/2, randomised, double-blind, active comparator-controlled, multicentre, US-based trial

BACKGROUND

A pneumococcal conjugate vaccine (PCV) specifically focused on serotypes associated with adult residual disease burden is urgently needed. We aimed to assess V116, an investigational 21-valent PCV, that contains pneumococcal polysaccharides (PnPs), which account for 74-94% of invasive pneumococcal disease in adults aged 65 years or older.

METHODS

We did a phase 1/2, randomised, double-blind, active comparator-controlled, multicentre, non-inferiority and superiority trial. The phase 1 study was done at two clinical sites in the USA, and the phase 2 study was done in 18 clinical sites in the USA. Eligible participants were healthy adults with or without chronic medical conditions assessed as stable, aged 18-49 years in the phase 1 trial and aged 50 years or older in the phase 2 trial. Participants were excluded if they had a history of invasive pneumococcal disease or other culture-positive pneumococcal disease within the past 3 years, known hypersensitivity to a vaccine component, known or suspected impairment of immunological function, were pregnant or were breastfeeding, or had previously received any pneumococcal vaccine. Participants had to abstain from sexual activity or use protocol approved contraception. All participants were centrally randomly assigned to a vaccine group using an interactive response technology system. Participants and investigators were masked to group assignment. In phase 1, participants were randomly assigned (1:1:1) to receive a single dose of V116-1 (2 μg per pneumococcal polysaccharide [PnP] per 0·5 mL) or V116-2 (4 μg per PnP per 1·0 mL) or the 23-valent unconjugated PnP vaccine, PPSV23 (25 μg per PnP per 0·5 mL). In phase 2, participants were randomly assigned (1:1) to receive one dose of V116 (4 μg per PnP per 1·0 mL) or PPSV23 (25 μg per PnP per 0·5 mL), stratified by age. Safety analyses included all randomly assigned participants who received study vaccine; immunogenicity analyses were per protocol. For both phases, the primary safety outcome was the proportion of participants with solicited injection-site adverse events and solicited systemic adverse events up to day 5 after vaccination and the proportion of participants with vaccine-related serious adverse events to 6 months after vaccination. In phase 2, primary immunogenicity outcomes were to test non-inferiority of V116 compared with PPSV23 as measured by serotype-specific opsonophagocytic antibody geometric mean titres (OPA-GMT) ratios for the serotypes common to the two vaccines at 30 days after vaccination (using a 0·33 margin) and to test superiority of V116 compared with PPSV23 as measured by serotype-specific OPA-GMT ratios for the serotypes unique to V116 at 30 days after vaccination (using a 1·0 margin). This trial is registered with Clinicaltrials.gov, NCT04168190.

FINDINGS

Between Dec 6 and 26, 2019, 92 volunteers were screened and 90 (98%) enrolled for phase 1 (59 [66%] women; 31 [34%] men); 30 participants were assigned to each group and received study vaccine. 30 (100%) participants in the V116-1 group, 29 (97%) in the V116-2 group, and 30 (100%) participants in the PPSV23 group were included in the per-protocol immunogenicity evaluation. From Sept 23, 2020, to Jan 12, 2021, 527 volunteers were screened, and 510 (97%) participants were enrolled in the phase 2 trial. 508 participants (>99%; 254 [100%] of 254 participants randomly assigned to the V116 group and 254 [99%] of 256 randomly assigned to PPSV23 group) received study vaccine (281 [55%] women; 227 [45%] men). 252 (99%) of 254 of participants in the V116 group and 254 (99%) of 256 participants in the PPSV23 group were included in the primary immunogenicity analyses. There were no vaccine-related serious adverse events or vaccine-related deaths in either study phase. In both phases, the most common solicited injection site adverse event was injection site pain (phase 1 22 [73%] participants in V116-1 group, 23 [77%] participants in V116-2 group, and 17 [57%] participants in the PPSV23 group; phase 2 118 [46%] of 254 participants in the V116 group and 96 [38%] of 254 in the PPSV23 group]. The most common solicited systemic adverse events in phase 1 was fatigue (eight [27%] participants in the V116-1 group, eight [27%] participants in the V116-2 group, and five [17%] participants in PPSV23 group) and myalgia (eight [27%] participants in the V116-1 group, nine (30%) participants in the V116-2 group, and four (13%) participants in the PPSV23 group]. In phase 2, the most frequently reported solicited systemic adverse event was fatigue (49 [19%] participants in V116 group, and 31 [12%] participants in PPSV23 group). In both phases, most of the solicited adverse events in all vaccine groups were mild and of short duration (≤3 days). V116 met non-inferiority criteria compared with PPSV23 for the 12 shared serotypes and met superiority criteria compared to PPSV23 for the nine unique serotypes.

INTERPRETATION

V116 was well tolerated with a safety profile generally similar to PPSV23; consistent with licensed pneumococcal conjugate vaccines. Functional OPA antibodies were induced to all V116 vaccine serotypes. The vaccine was non-inferior to PPSV23 for the 12 serotypes common to both vaccines and superior to PPSV23 for the nine unique serotypes in V116. Our findings support the development of V116 for prevention of pneumococcal disease in adults.

FUNDING

Merck Sharp & Dohme, subsidiary of Merck & Co, Rahway, NJ, USA.

Preclinical evaluation of an investigational 21-valent pneumococcal conjugate vaccine, V116, in adult-rhesus monkey, rabbit, and mouse models

Despite the widespread effectiveness of pneumococcal conjugate vaccines on the overall incidence of invasive pneumococcal disease, the global epidemiological landscape continues to be transformed by residual disease from non-vaccine serotypes, thus highlighting the need for vaccines with expanded disease coverage. To address these needs, we have developed V116,an investigational 21-valent non-adjuvanted pneumococcal conjugate vaccine (PCV),containingpneumococcal polysaccharides (PnPs) 3, 6A, 7F, 8, 9N, 10A, 11A,12F, 15A, 16F, 17F, 19A, 20, 22F, 23A, 23B, 24F, 31, 33F, 35B, anda de-O-acetylated 15B(deOAc15B) individually conjugated to the nontoxic diphtheria toxoid CRM197 carrier protein. Preclinical studies evaluated the immunogenicity of V116 inadult monkeys, rabbits, and mice. Following one dose, V116 was found to be immunogenic in preclinical animal species and induced functional antibodies for all serotypes included in the vaccine, in addition to cross-reactive functional antibodies to serotypes 6C and 15B. In these preclinical animal studies, the increased valency of V116 did not result in serotype-specific antibody suppression when compared to lower valent vaccines V114 or PCV13. In addition, when compared with naïve controls, splenocytes from V116 to immunized animals demonstrated significant induction of CRM197-specific T cells in both IFN-γ and IL-4 ELISPOT assays, as well as Th1 and Th2 cytokine induction through in vitro stimulation assays, thus suggesting the ability of V116 to engage T cell dependent immune response pathways to aid in development of memory B cells. V116 also demonstrated significant protection in mice from intratracheal challenge with serotype 24F, a novel serotype not contained in any currently licensed vaccine.

Streptococcus Pneumoniae Bacteremia with Acute Kidney Injury and Transient ADAMTS13 Deficiency

A 43-year-old woman with a medical history of splenectomy for immune thrombocytopenic purpura was diagnosed with Streptococcus pneumoniae bacteremia. Her initial complaints were fever and more importantly painful extremities that appeared cyanotic. During her hospitalisation, she never developed cardiocirculatory failure but presented acute kidney injury (AKI) with oliguria. Laboratory investigations confirmed AKI with serum creatinine 2.55 mg/dL which peaked at 6.49 mg/dL. There was also evidence for disseminated intravascular coagulation (DIC) with decreased platelet count, low fibrinogen levels, and high D-dimer levels. There were no signs of haemolytic anaemia. The initial ADAMTS13 activity was low (17%) but slowly recovered. Renal function progressively improved with supportive therapy, as opposed to the progressing skin necrosis. The association of DIC and low ADAMTS13 activity may have contributed to the severity of microthrombotic complications, even in the absence of thrombotic microangiopathy as thrombotic thrombocytopenic purpura (TTP) or pneumococcal-associated haemolytic uremic syndrome (pa-HUS).

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.

Pneumococcal nasopharyngeal carriage in children under 5 years of age at an outpatient healthcare facility in Novi Sad, Serbia during the COVID-19 pandemic

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The prevalence of nasopharyngeal pneumococcal carriage in children aged 24–60 months was 31.7%.

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The prevalence was high and increased during the coronavirus disease 2019 (COVID-19) pandemic.

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This ruled out a major role of COVID-19 in suppressing carriage and, probably, transmission.

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The dominant serotypes were 15B, 6B, 19F, 11A, 6C, 6A, 3, 23F and 19A.

Objectives

To assess whether pneumococcal nasopharyngeal carriage among children aged 24–60 months reduced during the coronavirus disease 2019 (COVID-19) pandemic in Novi Sad, Serbia, and to investigate the overall prevalence of carriage, serotype distribution and dominant serotypes 2–3 years after the introduction of pneumococcal conjugate vaccine 10.

Design and methods

This prospective, observational study was conducted in February–March 2020, September–November 2020 and April–June 2021, enabling the comparison of results in the pre-pandemic/early pandemic period with two periods during the COVID-19 pandemic. Pneumococci were identified by standard microbiological methods. Serotype identification was performed using conventional multiplex polymerase chain reaction assays.

Results

Among 1623 children tested, 515 (31.7%, 95% confidence interval 29.4–34.0%) carried pneumococci. A significant increase in prevalence was found between February–March 2020 and September–November 2020 (P=0.0085), with no difference found between September–November 2020 and April–June 2021 (P=0.0524). Pneumococcal colonization was significantly higher in children who were fully vaccinated and among children who attended day care centres. The dominant serotypes were 15B, 6B, 19F, 11A, 6C, 6A, 3, 23F and 19A, representing 66.4% of all isolates.

Conclusions

This study found that pneumococcal nasopharyngeal carriage in children aged 24–60 months was high before the COVID-19 pandemic, and then increased during the pandemic. This rules out a major role of COVID-19 in the suppression of carriage and, probably, transmission.

Burden of pneumococcal disease due to serotypes covered by the 13-valent and new higher-valent pneumococcal conjugate vaccines in the United States

The addition of pneumococcal conjugate vaccines (PCVs) to the United States (US) national immunization program led to significant reductions in incidence, mortality, and associated sequelae caused by pneumococcal disease (PD) in children and adults through direct and indirect protection. However, there remains clinical and economic burden due to PD caused by serotypes not included in the current 13-valent PCV (PCV13) formulation. To address this unmet need, 15-valent PCV (PCV15) and 20-valent PCV (PCV20), containing additional serotypes to PCV13, were recently approved in the US for adults and are anticipated for pediatrics in the near future. The study objective was to estimate the annual number of cases, deaths, and economic burden of PD due to serotypes included in PCV13, PCV15, and PCV20 for both US pediatric and adult populations. An Excel-based model was developed to calculate clinical and economic outcomes using published age-group specific serotype coverage; incidence of invasive PD, community-acquired pneumonia, and acute otitis media; case fatality rates; and disease-related costs. The results showed that across all age groups, the estimated annual PD cases and associated deaths covered by PCV13 serotypes were 914,199 and 4320, respectively. Compared with PCV13 serotypes, the additional 2 and 7 serotypes covered by PCV15 and PCV20 were attributed with 550,475 and 991,220 annual PD cases, as well as 1425 and 3226 annual deaths, respectively. This clinical burden translates into considerable economic costs ranging from $903 to $1,928 million USD that could be potentially addressed by PCV15 and PCV20. The additional serotypes included in PCV20 contribute substantially to the clinical and economic PD burden in the US pediatric and adult populations. Despite the success of the PCV13 pediatric national immunization program and increased adult uptake of PCV13 and 23-valent polysaccharide vaccine, broader PCV serotype coverage is needed across all ages to further reduce pneumococcal disease burden.

Pneumococcal serotypes in adults hospitalized with community-acquired pneumonia in Greece using urinary antigen detection tests: the EGNATIA study, November 2017 - April 2019

Greece introduced a 13-valent pneumococcal conjugate vaccine (PCV13) into the infant national immunization program in 2010 (3 + 1 schedule until June 2019). Since 2015, PCV13 has been recommended for adults aged 19-64 years with comorbidities and adults ≥65 years sequentially with 23-valent pneumococcal polysaccharide vaccine (PPSV23). We examined pneumococcal serotype distribution among Greek adults aged ≥19 years hospitalized with community-acquired pneumonia (CAP) during November 2017-April 2019. This was an interim analysis of EGNATIA, a prospective study of adult hospitalized CAP in the cities of Ioannina and Kavala. Pneumococcus was identified using cultures, BinaxNow®, serotype-specific urinary antigen detection assays (UAD-1/2). Our analysis included overall 482 hospitalized CAP patients (mean age: 70.5 years; 56.4% male). 53.53% of patients belonged to the highest pneumonia severity index (PSI) classes (IV-V). Pneumococcus was detected in 65 (13.5%) patients, with more than half (57%) of cases detected only by UAD. Approximately two-thirds of pneumococcal CAP occurred in those aged ≥65 years (n = 40, 8.3% of CAP). More than half of pneumococcal CAP (n = 35, 53.8%) was caused by PCV13 serotypes. Most frequently detected PCV13 serotypes were 3, 19A, 23F, collectively accounting for 83% of PCV13 vaccine-type (VT) CAP and 6% of all-cause CAP. Overall, 82.9% of PCV13 VT CAP occurred among persons with an indication (age/risk-based) for PCV13 vaccination. Even with a mature PCV13 childhood immunization program, a persistent burden of PCV13 VT CAP exists in Greek adults. Strategies to increase PCV13 (and higher-valency PCVs, when licensed) coverage in adults should be implemented to reduce the disease burden.

Streptococcus pneumoniae Serotypes Associated with Death, South Africa, 2012-2018

The Streptococcus pneumoniae polysaccharide capsule plays a role in disease severity. We assessed the association of serotype with case-fatality ratio (CFR) in invasive pneumococcal disease (IPD) and meningitis in South Africa, 2012-2018 (vaccine era), using multivariable logistic regression by manual backward elimination. The most common serotypes causing IPD were 8 and 19A. In patients <15 years of age, serotypes associated with increased CFR in IPD, compared with serotype 8 and controlling for confounding factors, were 11A, 13, 19F, 15A, and 6A. None of these serotypes were associated with increased CFR in meningitis. Among IPD patients >15 years of age, serotype 15B/C was associated with increased CFR. Among meningitis patients of all ages, serotype 1 was associated with increased CFR. PCV13 serotypes 1, 3, 6A, 19A, and 19F should be monitored, and serotypes 8, 12F, 15A, and 15B/C should be considered for inclusion in vaccines to reduce deaths caused by S. pneumoniae.

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.

Serotype distribution and antimicrobial resistance of Streptococcus pneumoniae in the Philippines, 2012-2018

OBJECTIVE

Data are scarce on the prevailing Streptococcus pneumoniae serotypes in the Philippines, including the relative antimicrobial resistance (AMR) of these bacteria. This study is designed to fill that gap by describing the serotype distribution and AMR of S. pneumoniae in the Philippines from 2012 to 2018.

METHODS

S. pneumoniae isolates from clinical specimens were collected through the Philippine Department of Health Antimicrobial Resistance Surveillance Program from 1 January 2012 to 31 December 2018. Identification and antimicrobial susceptibility testing (AST) were performed using conventional and automated methods (Vitek2 Compact Automated Machine). AST for penicillin, erythromycin, co-trimoxazole, ceftriaxone and levofloxacin was done following the Clinical and Laboratory Standard Institute recommendations. Serotyping was done through slide agglutination following the Denka Seiken slide agglutination method.

RESULTS

From a total of 307 isolates of S. pneumoniae, 32 serotypes were identified; the most frequently occurring were serotypes 1, 3, 5, 4, 18, 19A, 6B, 15 and 14. Many (n = 113, 36.53%) of the isolates were from those aged £5 years. Pneumococcal conjugate vaccine (PCV) coverage was as follows: PCV7 (32.69%), PCV10 (54.16%) and PCV13 (69.23%). The overall AMR of invasive S. pneumoniae isolates was low. Penicillin-resistant serotypes were 14, 19, 24, 4, 5, 1, 15, 6 and 32.

DISCUSSION

With the inclusion of PCV13 in the National Immunization Program, continued monitoring of the prevailing serotypes of S. pneumoniae isolates in the Philippines is needed to guide disease and AMR control measures.

Matching-adjusted indirect comparison of pneumococcal vaccines V114 and PCV20

BACKGROUND

V114 (15-valent pneumococcal conjugate vaccine [PCV15]) and a 20-valent PCV (PCV20) are approved for adults (≥18 years) in the United States. We present methodologies to indirectly compare immune responses to V114 versus PCV20.

RESEARCH DESIGN AND METHODS

Indirect treatment comparison and matching-adjusted indirect comparison (MAIC) were performed to estimate opsonophagocytic activity (OPA) geometric mean titer (GMT) ratios of V114/PCV20 at 30 days post-vaccination with PCV13 as common comparator for 13 serotypes (STs) shared with a 13-valent PCV (PCV13) among pneumococcal vaccine-naïve adults aged ≥60 years. Data from three V114 studies were pooled (V114, N = 2,196; PCV13, N = 843). In the MAIC analysis, data were reweighted, matching participant age and sex in NCT03760146 (PCV20, N = 1,507; PCV13, N = 1,490).

RESULTS

The lower bound of V114/PCV20 OPA GMT ratio for all PCV13 STs is greater than the prespecified  0.5 non-inferiority margin and those for five PCV13 STs (3, 6A, 6B, 18C, and 23F) are greater than the prespecified 1.2 superiority margin. V114 was associated with 77% greater OPA GMT for ST3 versus PCV20.

CONCLUSION

V114 was non-inferior to PCV20 for all PCV13 STs and statistically superior for five PCV13 STs.

Safety and Immunogenicity of a 20-valent Pneumococcal Conjugate Vaccine in Healthy Infants in the United States

BACKGROUND

The development and widespread use of pneumococcal conjugate vaccines (PCVs) substantially reduced the global burden of pneumococcal disease. Expanding the serotypes covered by PCVs may further reduce disease burden. A 20-valent PCV (PCV20) has been developed to add coverage for 7 additional serotypes (8, 10A, 11A, 12F, 15B, 22F and 33F) to those in the existing 13-valent PCV (PCV13). This phase 2 study evaluated the safety, tolerability and immunogenicity of PCV20 in healthy US infants.

METHODS

In this randomized, active-controlled, double-blind study, 460 infants were randomized 1:1 to receive a 4-dose series of either PCV20 or PCV13 at 2, 4, 6 and 12 months of age. Solicited local reactions and systemic events, adverse events (AEs) and serious AEs were recorded. Immunogenicity was assessed by measuring serotype-specific IgG concentrations and opsonophagocytic activity titers at 1 month after Dose 3, before Dose 4 and 1 month after Dose 4.

RESULTS

Of 460 infants, 82.8% completed the 1-month visit after Dose 4. Local reactions and systemic events were mostly mild to moderate in severity and similar between the PCV20 and PCV13 groups. Treatment-related AEs were uncommon, with no related serious AEs or deaths reported. IgG and opsonophagocytic activity responses elicited by PCV20 were robust and demonstrated a booster response after Dose 4.

CONCLUSIONS

Administration of PCV20 in US infants was well tolerated, with a safety profile similar to PCV13, and induced robust serotype-specific immune responses. These findings support continued development of PCV20 in the pediatric population.

A randomized phase 1/2 study of the safety and immunogenicity of a multivalent pneumococcal conjugate vaccine in healthy adults 50 through 85 years of age

Pneumococcal disease can be serious and debilitating in older adults. Pneumococcal conjugate vaccines (PCVs), such as the 13-valent PCV (PCV13), reduce pneumococcal disease rates caused by vaccine serotypes. Development of PCVs offering additional coverage against serotypes not contained in PCV13 can reduce disease burden further. The complementary 7-valent PCV (cPCV7) contains seven non-PCV13 serotypes (8, 10A, 11A, 12F, 15B, 22F, 33F) and can expand coverage by supplementing direct or indirect protection from existing PCVs. This phase 1/2, randomized, active-controlled, observer-blinded study evaluated cPCV7 safety and immunogenicity in healthy adults 50–85 years of age. Stage 1 randomized 66 healthy adults (50–64 years) naive to pneumococcal vaccines to receive cPCV7 or licensed tetanus, diphtheria, and acellular pertussis vaccine; Stage 2 randomized 445 healthy adults (65–85 years) previously vaccinated with PCV13 to receive cPCV7 or 23-valent polysaccharide vaccine. Local reactions and systemic events up to 14 days and adverse events (AEs) through 1 month after vaccination were assessed. Immunogenicity was evaluated by serotype-specific opsonophagocytic activity (OPA) assays before and 1 month after vaccination (and after 12 months in Stage 2). Rates of local reactions, systemic events, and AEs were generally similar after receipt of cPCV7 or control. Robust OPA responses were observed for all seven serotypes 1 month after cPCV7; titers declined yet remained above baseline 12 months after vaccination. Overall, this study found that in adults ≥50 years of age, cPCV7 was safe, well tolerated, and elicited functional immune responses to vaccine serotypes. ClinicalTrials.gov: NCT03313050

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).

A randomized phase 1 study of the safety and immunogenicity of 2 novel pneumococcal conjugate vaccines in healthy Japanese adults in the United States

Expanding serotype coverage of pneumococcal conjugate vaccines (PCVs) to target prevailing disease-causing serotypes could further reduce disease burden. To address this need, 2 different PCVs have been investigated: a 20-valent PCV (PCV20; includes the 13 serotypes in the 13-valent PCV [PCV13] plus 7 additional serotypes [8, 10A, 11A, 12F, 15B, 22F, 33F]) and a complementary 7-valent PCV (cPCV7; contains only the 7 additional serotypes). This phase 1b, randomized, controlled, double-blind study evaluated PCV20 and cPCV7 safety and immunogenicity in healthy Japanese adults 18–49 years of age residing in the United States for ≤5 years. Participants (n = 104) were randomized equally to receive a single dose of PCV20, cPCV7, or PCV13. Immunogenicity was assessed at baseline and 1 month after vaccination using serotype-specific opsonophagocytic activity (OPA) titers and serotype-specific immunoglobulin G (IgG) concentrations. Prompted local reactions and systemic events; adverse events (AEs); and serious AEs and newly diagnosed chronic disease were assessed 14 days, through 1 month, and upto 6 months following vaccination, respectively. OPA immune responses were robust for all 20 serotypes in the PCV20 group and for the 7 serotypes in the cPCV7 group 1 month after vaccination. IgG immune response showed similar trends. Injection site pain and muscle pain were the most common local reaction and systemic event; the majority were mild or moderate in severity. Few AEs and no severe AEs, serious AEs, or safety-related withdrawals were reported. Taken together, administration of PCV20 or cPCV7 in Japanese adults was well tolerated and induced robust serotype-specific functional immune responses. NCT03642847.

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.

Global Landscape Review of Serotype-Specific Invasive Pneumococcal Disease Surveillance among Countries Using PCV10/13: The Pneumococcal Serotype Replacement and Distribution Estimation (PSERENADE) Project

Serotype-specific surveillance for invasive pneumococcal disease (IPD) is essential for assessing the impact of 10- and 13-valent pneumococcal conjugate vaccines (PCV10/13). The Pneumococcal Serotype Replacement and Distribution Estimation (PSERENADE) project aimed to evaluate the global evidence to estimate the impact of PCV10/13 by age, product, schedule, and syndrome. Here we systematically characterize and summarize the global landscape of routine serotype-specific IPD surveillance in PCV10/13-using countries and describe the subset that are included in PSERENADE. Of 138 countries using PCV10/13 as of 2018, we identified 109 with IPD surveillance systems, 76 of which met PSERENADE data collection eligibility criteria. PSERENADE received data from most (n = 63, 82.9%), yielding 240,639 post-PCV10/13 introduction IPD cases. Pediatric and adult surveillance was represented from all geographic regions but was limited from lower income and high-burden countries. In PSERENADE, 18 sites evaluated PCV10, 42 PCV13, and 17 both; 17 sites used a 3 + 0 schedule, 38 used 2 + 1, 13 used 3 + 1, and 9 used mixed schedules. With such a sizeable and generally representative dataset, PSERENADE will be able to conduct robust analyses to estimate PCV impact and inform policy at national and global levels regarding adult immunization, schedule, and product choice, including for higher valency PCVs on the horizon.

Streptococcus pneumoniae serotype 22F infection in respiratory syncytial virus infected neonatal lambs enhances morbidity

Respiratory syncytial virus (RSV) is the primary cause of viral bronchiolitis resulting in hospitalization and a frequent cause of secondary respiratory bacterial infection, especially by Streptococcus pneumoniae (Spn) in infants. While murine studies have demonstrated enhanced morbidity during a viral/bacterial co-infection, human meta-studies have conflicting results. Moreover, little knowledge about the pathogenesis of emerging Spn serotype 22F, especially the co-pathologies between RSV and Spn, is known. Here, colostrum-deprived neonate lambs were divided into four groups. Two of the groups were nebulized with RSV M37, and the other two groups were mock nebulized. At day three post-RSV infection, one RSV group (RSV/Spn) and one mock-nebulized group (Spn only) were inoculated with Spn intratracheally. At day six post-RSV infection, bacterial/viral loads were assessed along with histopathology and correlated with clinical symptoms. Lambs dually infected with RSV/Spn trended with higher RSV titers, but lower Spn. Additionally, lung lesions were observed to be more frequent in the RSV/Spn group characterized by increased interalveolar wall thickness accompanied by neutrophil and lymphocyte infiltration and higher myeloperoxidase. Despite lower Spn in lungs, co-infected lambs had more significant morbidity and histopathology, which correlated with a different cytokine response. Thus, enhanced disease severity during dual infection may be due to lesion development and altered immune responses rather than bacterial counts.

Emergence of Meningitis Caused by Nonvaccine Serotypes of Pneumococcus in Rural United States

Pneumococcal conjugate vaccines have decreased the rates of invasive pneumococcal disease (IPD) in children. Since vaccine introduction, however, rates of infection due to nonvaccine Streptococcus pneumoniae serotypes have increased. We now describe 3 meningitis cases due to the nonvaccine serotypes 35B and 11A from rural United States.

Safety, Tolerability, and Immunogenicity of a 20-Valent Pneumococcal Conjugate Vaccine (PCV20) in Adults 60 to 64 Years of Age

Background

Pneumococcal conjugate vaccines (PCVs) have significantly decreased pneumococcal disease worldwide; however, expanding serotype coverage may further reduce disease burden. A 20-valent PCV (PCV20) containing capsular polysaccharide conjugates of serotypes present in the 13-valent PCV (PCV13) and 7 new serotypes (8, 10A, 11A, 12F, 15B, 22F, and 33F) is currently in development. This phase 2 study evaluated safety, tolerability, and immunogenicity of PCV20 in adults without prior pneumococcal vaccination.

Methods

In this randomized, active-controlled, double-blinded trial, 444 adults 60 through 64 years of age were randomized to receive either a single dose of PCV20 followed 1 month later by saline placebo or a single dose of PCV13 followed 1 month later by 23-valent polysaccharide vaccine. Local injection site reactions, select systemic symptoms, and adverse events (AEs) were recorded. Immunogenicity was assessed by measuring serotype-specific opsonophagocytic activity (OPA) titers before and approximately 1 month after each vaccination.

Results

Local reaction and systemic event rates were similar after vaccination with PCV20 or PCV13; no serious vaccine-related AEs were reported. In the PCV20 group, functional immune responses as measured by OPA were robust for all 20 serotypes included in the vaccine, with geometric mean fold rises from baseline ranging from 6.0 to 113.4.

Conclusions

PCV20 was well tolerated in adults 60 to 64 years of age, with a safety profile consistent with historical experience of PCVs in this age group. Substantial OPA responses were elicited against all serotypes. Results demonstrate the potential for PCV20 to expand pneumococcal disease protection.

Clinical Trials Registration

NCT03313037.

Hospital-based sentinel surveillance for Streptococcus pneumoniae and other invasive bacterial diseases in India (HBSSPIBD): design and methodology

INTRODUCTION

Streptococcus pneumoniae is one of the frequently isolated organisms and an important aetiological agent of invasive bacterial diseases (IBD) like pneumonia, meningitis and sepsis. As a measure to control the burden of IBD, the Government of India introduced Pneumoccocal Conjugate Vaccine-13 (PCV-13) in the Universal Immunization Program in high burden districts of five states in a phased manner from 2017 onwards. It is essential to understand the trend of circulating pneumococcal serotypes associated with IBD in the prevaccination and postvaccination scenarios to decide on the expansion of vaccination programmes and PCV reformulation. This manuscript describes the protocol for hospital-based sentinel surveillance for S. pneumoniae and other organisms causing IBD across various geographical regions in India.

METHODS AND ANALYSIS

Hospital-based surveillance is established in selected hospitals to recruit children aged 1-59 months with symptoms of pneumonia and other IBD. Diagnostic criteria were adapted from standard WHO case definitions. Case Report Forms (CRFs) are used to collect data from the enrolled children. Blood, cerebrospinal fluid (CSF) and other normally sterile body fluids are collected and subjected to microscopy, cytology, latex agglutination, biochemistry, bacteriological culture and real-time PCR as applicable. Pneumococcal isolates are serotyped and tested for assessing antimicrobial resistance patterns. Data will be analysed by simple descriptive statistics to estimate the proportion of pneumonia and other IBD due to S. pneumoniae, Hemophilus influenzae type b and Neisseria meningitidis. Prevalence of bacterial infection, circulating pneumococcal serotypes, antibiotic resistance patterns, serotype variability across seasons and regions will be described in terms of percentage with 95% confidence interval.

ETHICS AND DISSEMINATION

The institutional review boards of the coordinating centre, all sentinel sites, regional and national reference laboratories approved the project. The results will be published in peer-reviewed journals and shared with stakeholders for deciding on revising vaccination strategy appropriately.

Clinical Relevance and Molecular Pathogenesis of the Emerging Serotypes 22F and 33F of Streptococcus pneumoniae in Spain

Streptococcus pneumoniae is the main bacterial cause of respiratory infections in children and the elderly worldwide. Serotype replacement is a frequent phenomenon after the introduction of conjugated vaccines, with emerging serotypes 22F and 33F as frequent non-PCV13 serotypes in children and adults in North America and other countries. Characterization of mechanisms involved in evasion of the host immune response by these serotypes is of great importance in public health because they are included in the future conjugated vaccines PCV15 and PCV20. One of the main strategies of S. pneumoniae to persistently colonize and causes infection is biofilm formation. In this study, we have evaluated the influence of capsule polysaccharide in biofilm formation and immune evasion by using clinical isolates from different sources and isogenic strains with capsules from prevalent serotypes. Since the introduction of PCV13 in Spain in the year 2010, isolates of serotypes 22F and 33F are rising among risk populations. The predominant circulating genotypes are ST433^22F and ST717^33F, being CC433 in 22F and CC717 in 33F the main clonal complexes in Spain. The use of clinical isolates of different origin, demonstrated that pediatric isolates of serotypes 22F and 33F formed better biofilms than adult isolates and this was statistically significant. This phenotype was greater in clinical isolates from blood origin compared to those from cerebrospinal fluid, pleural fluid and otitis. Opsonophagocytosis assays showed that serotype 22F and 33F were recognized by the PSGL-1 receptor on leukocytes, although serotype 22F, was more resistant than serotype 33F to phagocytosis killing and more lethal in a mouse sepsis model. Overall, the emergence of additional PCV15 serotypes, especially 22F, could be associated to an enhanced ability to divert the host immune response that markedly increased in a biofilm state. Our findings demonstrate that pediatric isolates of 22F and 33F, that form better biofilm than isolates from adults, could have an advantage to colonize the nasopharynx of children and therefore, be important in carriage and subsequent dissemination to the elderly. The increased ability of serotype 22F to avoid the host immune response, might explain the emergence of this serotype in the last years.

Molecular characterization of predominant Streptococcus pneumoniae serotypes causing invasive infections in Canada: the SAVE study, 2011-15

Objectives

This study characterized the 11 most predominant serotypes of invasive Streptococcus pneumoniae infections collected by the annual SAVE study in Canada, between 2011 and 2015.

Methods

A subset of the 11 most predominant serotypes (7F, 19A, 22F, 3, 12F, 11A, 9N, 8, 33F, 15A and 6C) collected by the SAVE study was analysed using PFGE and MLST, as well as PCR to identify pilus-encoding genes. WGS analyses were performed on a subset of the above isolates plus a random selection of background strains.

Results

Of the predominant serotypes analysed, 7F, 33F and 19A were obtained more commonly from children <6 years of age, whereas 15A, 6C, 22F and 11A were more common in adults >65 years of age. Pneumococcal pilus PI-1 was identified in antimicrobial-susceptible serotype 15A (61/212) and <10% of 6C isolates (16/188). PI-2 was found in serotype 7F (683/701) and two-thirds of 11A isolates (162/241). Only serotype 19A-ST320 possessed both pili. Molecular and phylogenetic analyses identified serotypes 19A, 15A, 6C, 9N and 33F as highly diverse, whereas 7F, 22F and 11A demonstrated clonality. Antimicrobial resistance determinants were common within diverse serotypes, and usually similar within a clonal complex.

Conclusions

Despite successful use of conjugate vaccines, S. pneumoniae remains a highly diverse organism in Canada. Several predominant serotypes, both antimicrobial susceptible and MDR, have demonstrated rapid clonal expansion or an increase in diversity. As S. pneumoniae continues to evolve in Canada, WGS will be a necessary component in the ongoing surveillance of antimicrobial-resistant and expanding clones.

Pneumococcal carriage among adults aged 50 years and older with co-morbidities attending medical practices in Rome, Italy

BACKGROUND

Data on Streptococcus pneumoniae carriage in adults with co-morbidities are limited. In this study we estimated the pneumococcal carriage among adults with co-morbidities and evaluated socio-demographic and clinical risk factors. The potential coverage of the current pneumococcal vaccines recommended for adults (PCV13 and PPV23) was also investigated.

METHODS

A cross-sectional study on S. pneumoniae carriage among unvaccinated adults ≥50 years with co-morbidities, presenting with or without acute respiratory symptoms at general practitioners in Rome, Italy, between October 2015 and July 2016 was conducted. Pneumococcal carriage was investigated by both cultural and molecular methods. Socio-demographic variables and co-morbidities were evaluated by logistic models as possible risk factors for pneumococcal carriage.

RESULTS

Out of 248 patients (median age: 73 yrs; IQR: 65-79), 12 (4.8%) and 83 (33.5%) individuals were found colonized using cultural or molecular methods, respectively. Potential risk factors for pneumococcal colonization as ascertained by molecular methods were: low level of education (adjusted OR = 3.71, 95% CI: 1.62-9.40), winter months (December-March vs other months, adjusted OR = 2.56, 95% CI: 1.29-5.14), and presence of chronic lung diseases (adjusted OR = 2.18, 95% CI: 1.15-4.16). The combination of serotype-specific multiplex RT-PCR and conventional PCR allowed to identify 22 serotypes/group of serotypes, of which the most common were: 24F/24A/24B, 12F/12A/12B/44/46, 6A/6B, 14, 15B/15C, and 22F/22A. Prevalence of pneumococcal carriage due to PCV13 serotypes and non-PCV13 serotypes was 23.6% and 67.3%, respectively. Prevalence of colonization due to PPV23 serotypes was estimated to be 54.6%.

CONCLUSIONS

A high prevalence of S. pneumoniae carriage was observed among adults with co-morbidities, especially among individuals affected by chronic lung diseases. These results support vaccine strategies based on the sequential administration of PCV13 and PPV23 to control potentially invasive pneumococcal strains in adults, especially in subjects with co-morbidities.

Hospital-onset adult invasive pneumococcal disease in Israel: Sicker patients, different pathogens

OBJECTIVES

Invasive pneumococcal disease (IPD) usually has its onset in the community (CO-IPD), but it can commence following hospitalization (HO-IPD). This study compared HO-IPD and CO-IPD cases during the implementation of the pneumococcal conjugate vaccine (PCV) program for children in Israel.

METHODS

This was a nationwide retrospective cohort study of adult (age >18 years) IPD patients covering the period from the implementation of the PCV7/13 program in 2009/2010 through 2015. HO-IPD and CO-IPD were defined as IPD with onset ≥4 and ≤2 days from admission, respectively. Patient characteristics, outcome measures, serotypes, and antimicrobial susceptibility were compared for the entire cohort, followed by a matched case-control analysis.

RESULTS

The study included 114 patients with HO-IPD and 2180 with CO-IPD. After matching HO-IPD to CO-IPD patients by age, sex, and comorbidities, the mortality rate and discharge to long-term care facility rate were significantly higher for HO-IPD patients than for CO-IPD patients (44.6% vs. 26.3% and 26.5% vs. 8.2%, respectively). HO-IPD isolates were less often covered by PCV13 (39.6% vs. 49.0%) and pneumococcal polysaccharide vaccine PPSV23 (56.6% vs. 71.3%) and more often resistant to penicillin (9.3% vs. 3.6%), ceftriaxone (3.8% vs. 0.75%), and levofloxacin (9.3% vs. 0.8%).

CONCLUSIONS

HO-IPD was associated with higher morbidity and mortality than CO-IPD and was more often caused by non-vaccine serotypes (primarily non-PCV13 types) and antibiotic-resistant strains.

A platform for glycoengineering a polyvalent pneumococcal bioconjugate vaccine using E. coli as a host

Chemical synthesis of conjugate vaccines, consisting of a polysaccharide linked to a protein, can be technically challenging, and in vivo bacterial conjugations (bioconjugations) have emerged as manufacturing alternatives. Bioconjugation relies upon an oligosaccharyltransferase to attach polysaccharides to proteins, but currently employed enzymes are not suitable for the generation of conjugate vaccines when the polysaccharides contain glucose at the reducing end, which is the case for ~75% of Streptococcus pneumoniae capsules. Here, we use an O-linking oligosaccharyltransferase to generate a polyvalent pneumococcal bioconjugate vaccine with polysaccharides containing glucose at their reducing end. In addition, we show that different vaccine carrier proteins can be glycosylated using this system. Pneumococcal bioconjugates are immunogenic, protective and rapidly produced within E. coli using recombinant techniques. These proof-of-principle experiments establish a platform to overcome limitations of other conjugating enzymes enabling the development of bioconjugate vaccines for many important human and animal pathogens.

Bioconjugation is a promising process to manufacture conjugate vaccines, but currently employed enzymes cannot generate the full spectrum of bacterial glycoproteins. Here, the authors use an O-linking oligosaccharyltransferase to generate a polyvalent pneumococcal bioconjugate vaccine with polysaccharides containing glucose at their reducing end.

Immunogenicity and protective efficacy of monovalent PCVs containing 22F and 33F polysaccharides in mouse models of colonization and co-infection

BACKGROUND

In the current transmission, we studied the immunogenicity and protective efficacy of serotypes 22F and 33F in the prevention of colonization and of invasive Streptococcus pneumoniae (Spn) pathogenesis during an influenza co-infection. Serotypes 22F and 33F are emerging Spn serotypes, which are not part of currently administered pneumococcal conjugate vaccine formulations (PCVs). Spn serotype 6A is an ingredient in the currently administered PCV13 vaccine and was therefore included in the study as a control.

METHODS

Adult (six weeks) and infant (two weeks) C57BL/6 mice were intranasally infected in the nasopharynx (NP) with Spn serotypes 22F, 33F, or 6A. Influenza A H1N1 A/Puerto Rico/8/193 virus (PR8) was introduced one day after the NP Spn colonization. In an immunization challenge study, mice were vaccinated with monovalent 22F, 33F, or 6A polysaccharide conjugated to the CRM₁₉₇ antigen. The immunized mice were colonized or co-infected to study the vaccines efficacy.

RESULTS

All three Spn serotypes established colonization in adult and infant mice. The co-infected mice showed an increase in Spn NP density. Invasive Spn infection (bacteremia) was observed following the co-infection with serotypes 22F and 6A but not 33F in adult mice, whereas infant mice developed bacteremia following co-infection with all three Spn serotypes. The vaccinations led to robust serum antibody responses to capsular polysaccharides 22F, 6A, and less for 33F. The vaccinations resulted in reductions of Spn NP colonization density for all three serotypes, prevention of bacteremia, and increased survival with Spn serotypes 22F and 6A. Passive transfer of antisera was associated with a reduction of Spn colonization densities in infant mice.

CONCLUSION

Vaccinations with monovalent 22F, 33F, or 6A formulations protect against Spn colonization, and the efficacy of the 22F vaccination was comparable to the 6A vaccination in preventing an invasive Spn bacterial infection during an influenza co-infection.

Streptococcus pneumoniae: prevalence in nasopharyngeal carriers of more than 50-years-old, in a Mexican rural community

INTRODUCTION

Streptococcus pneumoniae (Sp) is the main cause of community-acquired pneumonia in the elderly, hence the importance to establish the prevalence of nasopharyngeal colonization by different Sp serotypes in adults.

METHODS

from December 2009 to June 2010, nasopharyngeal cultures were taken from adults living in rural communities in Mexico for the isolation and serotyping of Sp by the Quellung reaction. Penicillin and ceftriaxone susceptibility tests were performed by the microdilution method.

RESULTS

two hundred and thirty-six adults over 50 years old, were included. The prevalence of colonization by Sp was 21.6%. The most frequent serotypes were 19A (21%), 6A (13%), 6B and 11A (11%). All isolates were susceptible to ceftriaxone, and 52.8% of the isolates showed penicillin minimal inhibitory concentrations ≥0.12mg/L.

CONCLUSION

this is the first study analyzing the nasopharyngeal colonization by Sp in adults in Mexico. Serotypes not included in any of the pneumococcal vaccines were frequently identified.