The shifting epidemiology and serotype distribution of invasive pneumococcal disease in Ontario, Canada, 2007-2017

Economic analysis of 15-valent and 20-valent pneumococcal conjugate vaccines among older adults in Ontario, Canada

BACKGROUND

Health Canada approved two new pneumococcal conjugate vaccines (PCV), 15-valent (PCV15) and 20-valent (PCV20), and we assessed their cost-effectiveness for older Ontarians.

RESEARCH DESIGN AND METHODS

We conducted a cost-utility analysis using an individual-level state transition model to compare one dose of PCV (alone or in series with PPV23) with PPV23-only. We estimated incremental cost-effectiveness ratios (ICERs) expressed in costs (C$2022) per quality-adjusted life year (QALY) from the healthcare payer perspective, discounted at 1.5% annually.

RESULTS

A sequential comparison of vaccinations with no indirect effect from childhood vaccination resulted in an ICER of $44,324/QALY for PCV15-alone compared to PPV23-only, and $70,751/QALY for PCV20-alone versus PCV15-alone. None of the PCV15/20 combined with PPV23 programs were cost-effective at a C$50,000/QALY threshold. PCV20 alone had an ICER of C$46,961/QALY compared to PPV23-only. When considering indirect effects, PCV15/20 alone or in series with PPV23 were not cost-effective. ICERs were mostly influenced by vaccine characteristics (effectiveness, waning, cost) and the incidence of pneumococcal community-acquired pneumonia.

CONCLUSIONS

Vaccinating older adults with PCV15/20 likely reduces burden of pneumococcal disease and would be cost-effective initially, but is expected to be less economically attractive in the longer term when herd immunity benefits from childhood vaccination programs are considered.

Immunogenicity and safety of a multi-human dose formulation of Biological E's 14-valent pneumococcal polysaccharide conjugate vaccine (PNEUBEVAX 14®) administered to 6-8-week-old healthy infants: a phase 3, single-blind, randomized, active-controlled study

Background

Pneumococcal conjugate vaccines (PCVs) have considerably reduced the burden of invasive pneumococcal disease (PD) worldwide. Consequently, though, there has been an increase in non-vaccine serotype-induced PD particularly at both the extremes of age. Biological E has developed a 14-valent PCV (PNEUBEVAX 14®) that includes additional serotypes 22F and 33F. PNEUBEVAX 14® was shown to be safe, immunogenic, and non-inferior to Prevenar-13® (PCV-13) when administered to infants in a pivotal phase 3 trial. In this study, the multi-dose presentation of PNEUBEVAX 14® with 2-phenoxyethanol as a preservative was assessed for safety and immunogenicity in infants.

Methods

This was a phase 3, single-blind, randomized, active-controlled study in 6-8-week-old healthy infants, conducted at three sites across India. The safety and immunogenicity of multi-dose presentation of PNEUBEVAX 14® were assessed in a 6-10-14-week dosing schedule, with 300 infants randomized to receive either PNEUBEVAX 14® or PCV-13. Safety-wise solicited local reactions and systemic events, unsolicited adverse events (AEs), serious AEs, and medically attended AEs (MAAEs) were recorded and analyzed. Immunogenicity was assessed by measuring anti-pneumococcal capsular polysaccharide (anti-PnCPS) immunoglobulin G (IgG) antibodies for all 14 serotypes, as well as cross-reactivity to serotype 6A.

Findings

The safety aspects of the multi-dose presentation of PNEUBEVAX 14® and PCV-13 were comparable with 23.3% of subjects having AEs in each of the two arms. There were no serious AEs, medically attended AEs, or deaths in either of the two study arms. Reported AEs were mild and solicited in nature, with injection site swelling and injection site pain being the most common AEs in both arms. The multi-dose presentation of PNEUBEVAX 14® was found to induce a robust immune response, including the new serotypes 22F and 33F. Importantly, PNEUBEVAX 14® also induced cross-reactive antibodies against serotype 6A.

Interpretation

The multi-dose presentation of PNEUBEVAX 14® is both safe and immunogenic when administered to 6-8-week-old infants in a 6-10-14-week dosing schedule. These results extend the findings of a pivotal phase 3 study of the single-dose presentation of PNEUBEVAX 14® that showed that it was safe, robustly immunogenic, and non-inferior to PCV-13 in the same age group and dosing schedule. Taken together, these data suggest that both the single-dose and multi-dose presentations of PNEUBEVAX 14® can be safely administered to infants to prevent pneumococcal disease caused by Streptococcus pneumoniae.

Clinical Trial Registration

https://ctri.nic.in/Clinicaltrials/pmaindet2.php?EncHid=NTk0MzA=&Enc=&userName=, identifier CTRI/2021/10/037067.

Comparison of 13-, 15- and 20-valent pneumococcal conjugate vaccines in the paediatric Canadian population: A cost-utility analysis

Background

Two pneumococcal conjugate vaccines, covering 15 and 20 Streptococcus pneumoniae serotypes (Pneu-C-15 and Pneu-C-20, respectively), were recently approved for use in the Canadian paediatric population.

Objective

To assess the cost-effectiveness of Pneu-C-15 and Pneu-C-20 in unvaccinated infants initiating routine pneumococcal vaccination, compared to the currently used 13-valent conjugate vaccine (Pneu-C-13).

Methods

A static cohort model was used to estimate sequential incremental cost-effectiveness ratios (ICERs in 2022 Canadian dollars per quality-adjusted life year [QALY]) of Pneu-C-13, Pneu-C-15 and Pneu-C-20 in the paediatric population starting their primary series. Costs and outcomes were calculated over a 10-year time horizon at the program level and a lifetime time horizon at the individual level and discounted at a rate of 1.5% per year. We explored the impact of uncertainties in model parameters and assumptions in scenario and sensitivity analyses.

Results

Routine use of Pneu-C-20 and, to a lesser extent, Pneu-C-15 is projected to reduce pneumococcal disease burden, compared to Pneu-C-13. Based on product cost assumptions, sequential ICERs for Pneu-C-15 and Pneu-C-20 were $58,800 and $135,200 per QALY gained from the health system perspective and $18,272 and $93,416 per QALY gained from the societal perspective, excluding indirect effects. A reduction in serotype-attributable disease due to indirect vaccine effects of 5% or greater resulted in ICERs below $30,000 per QALY gained for Pneu-C-15 and Pneu-C-20, with the optimal strategy determined by the magnitude and time to reach a reduction in pneumococcal disease.

Conclusion

Both Pneu-C-15 and Pneu-C-20 are expected to increase QALYs in Canadian children compared to Pneu-C-13 and may be cost-effective interventions.

A nationwide study of two decades of invasive pneumococcal disease in the Faroe Islands, 2000-2023

BACKGROUND

Invasive pneumococcal disease (IPD) remains a significant public health concern, particularly in vulnerable populations such as the elderly. This study focuses on the Faroe Islands, a unique setting for monitoring pneumococcal disease trends due to its high vaccination coverage and geographic isolation.

OBJECTIVE

To examine the prevalence, trends and serotype distribution of IPD in the Faroe Islands from 2000 to 2023, focusing on the impact of pneumococcal conjugate vaccines (PCVs) on disease incidence and serotype replacement.

METHODS

Eighty-six pneumococcal isolates, representing all registered cases of IPD in the Faroe Islands, were analysed during the study period. Data on patient demographics, serotype identification and vaccination history were collected from national health records. Temporal trends in vaccine-type (VT) and non-vaccine-type (nVT) serotypes were analysed, particularly following the introduction of PCV13 in 2010.

RESULTS

Following the introduction of PCV13, a shift from VT to nVT serotypes was observed, while the overall IPD rate remained stable. Notably, there was an increase in IPD cases among the elderly population. The analysis indicated that serotype replacement contributed to a rise in nVT cases despite reducing VT-related IPD.

CONCLUSIONS

The findings emphasise the need for ongoing evaluation of pneumococcal vaccine formulations and alternative strategies to address the increasing prevalence of nVT IPD. Higher-valency vaccines and sustained vaccination coverage are critical to mitigating the impact of serotype replacement and improving public health outcomes in the Faroe Islands.

Quantity and Quality of Naturally Acquired Antibody Immunity to the Pneumococcal Proteome Throughout Life

BACKGROUND

Young children and older adults are susceptible for invasive pneumococcal disease (IPD) caused by Streptococcus pneumoniae. Pneumococcal protein-specific antibodies play a protective role against IPD; however, not much is known about the pace of acquisition, maturation, and maintenance of these antibodies throughout life.

METHODS

Immunoglobulin G (IgG) and IgA levels, avidity, and/or specificity to the pneumococcal proteome in serum and saliva from healthy young children, adults, and older adults, with known carriage status, were measured by enzyme-linked immunosorbent assay (ELISA) and 2-dimensional western blotting against ΔcpsTIGR4.

RESULTS

Eleven-month-old children, the youngest age group tested, had the lowest pneumococcal proteome-specific IgG and IgA levels and avidity in serum and saliva, followed by 24-month-old children and were further elevated in adult groups. Among adult groups, the parents had the highest serum and saliva IgG and IgA antibody levels. In children, antibody levels and avidity correlated with daycare attendance and presence of siblings, posing as proxy for exposure and immunization. Immunodominance patterns slightly varied throughout life.

CONCLUSIONS

Humoral immunity against the pneumococcal proteome is acquired through multiple episodes of pneumococcal exposure. Low-level and low-avidity antiproteome antibody profiles in young children may contribute to their IPD susceptibility, while in overall antiproteome antibody-proficient older adults other factors likely play a role.

Nasopharyngeal carriage of Streptococcus pneumoniae among children aged 30 days to <60 months in Beijing and Shenzhen, China (2018-2021) during pneumococcal conjugate vaccine introduction and the coronavirus disease (COVID-19) pandemic

Objectives

To describe the carriage rate, serotype distribution, and antimicrobial susceptibility patterns of Streptococcus pneumoniae (S. pneumoniae) nasopharyngeal (NP) isolates among healthy children aged 30 days to <60 months in the cities of Beijing and Shenzhen during 2018-2021.

Methods

A NP swab sample was collected among four annual cohorts of healthy children at routine well-child visits. S. pneumoniae was identified by culture, optochin sensitivity and bile solubility, serotypes determined by latex agglutination and Quellung, and antimicrobial susceptibility testing performed using E-test strips.

Results

S. pneumoniae NP carriage was 13.1% (645/4,911), with the highest S. pneumoniae carriage prevalence (15.3%) observed in 25 to <60 months. The carriage prevalence was 15.1% in children 13-24 months, 13.2% in children 7-12 months, and 8.2% in children 30 days to 6 months (P < 0.01). Living with siblings [20.0% vs. 9.4%: OR: 2.42 (95% CI: 2.05-2.87)] or attending day-care [31.8% vs. 11.3%: OR: 3.67 (95% CI: 2.94-4.57)] increased the risk (P < 0.01). During the period (January 2020-April 2021) of strict non-pharmaceutical interventions to prevent and control the COVID-19 pandemic, the proportion of children with S. pneumoniae colonization declined from 16.0% (94/587) to 5.8% (108/1,848) in Beijing while increasing from 14.5% (64/443) to 18.6% (379/2,033) in Shenzhen. Among S. pneumoniae isolates, 36.7% (237/645) belonged to 13-valent pneumococcal conjugate vaccine (PCV13) serotypes, 64.3% (408/645) were non-PCV13 serotypes, including 20.8% (134/645) non-serotypeable S. pneumoniae (NST). A total of 158/644 isolates (24.5%) were MDR. For the PCV13 isolates, MDR was detected in 36.3% (86/237) of isolates; in comparison, 17.6% (72/407) of non-PCV13 serotypes, including NST, were MDR (P < 0.01). S. pneumoniae NP carriage was detected in 10.7% of children with previous pneumococcal vaccination (PCV7 or PCV13 only) compared with 14.9% in children without previous pneumococcal vaccination.

Conclusions

The highest S. pneumoniae carriage prevalence were found in the oldest age group (25 to <60 months) and in children living with siblings or attending day-care. Vaccination with PCV7 or PCV13 was associated with lower PCV13-serotype colonization. In Beijing, S. pneumoniae carriage significantly declined during the COVID-19 pandemic.

Invasive Pneumococcal Disease Epidemiology and Serotype Replacement After the Introduction of the 13-Valent Pneumococcal Conjugate Vaccine in Ontario, Canada, 2007-2022

Background

New vaccine products were recently authorized for protection against invasive pneumococcal disease (IPD) in Canada. Our aim was to determine age- and serotype-specific trends in IPD incidence and severity in Canada's largest province, Ontario.

Methods

We included all confirmed IPD cases reported in Ontario and defined the pre-pneumococcal 13-valent conjugate vaccine (PCV13) era (01/2007 to 12/2010), post-PCV13 era (01/2011 to 12/2019), and coronavirus disease 2019 (COVID-19) pandemic era (01/2020 to 12/2022). We estimated incidence, hospitalization, and case fatality rate (CFR) by age. We grouped IPD cases by vaccine-specific serotypes (PCV13; PCV15-non-PCV13; PCV20-non-PCV13; PCV20-non-PCV15; polysaccharide 23-valent vaccine-non-PCV20; and non-vaccine-preventable [NVP]). We then compared incidence rates by age and serotype group in the pre- and post-PCV13 eras by calculating rate ratios (RRs) and their 95% CIs.

Results

Incidence and hospitalizations declined from the pre- to post-PCV13 era in children aged <5 years (RR, 0.7; 95% CI, 0.6-0.8; and RR, 0.8; 95% CI, 0.7-0.9, respectively), but the CFR increased (1.4% to 2.3%). Other age groups saw smaller declines or more stable incidence rates across the years; hospitalizations increased in adults aged 50-64 years (RR, 1.2; 95% CI, 1.1-1.4) and ≥65 years (RR, 1.1; 95% CI, 1.0-1.1). For all ages, IPD cases and hospitalizations attributable to PCV13 serotypes declined, and those attributable to PCV15-non-PCV13, PCV20-non-PCV13, and NVP serotypes increased. IPD incidence declined during the COVID-19 era.

Conclusions

IPD incidence and hospitalizations due to PCV13 serotypes decreased after PCV13 introduction but increased for other serotypes. Continued surveillance is required to evaluate changes to pneumococcal vaccination programs and ongoing changes to the distribution of IPD-causing serotypes.

Serotype 3 Antibody Response and Antibody Functionality Compared to Serotype 19A Following 13-Valent Pneumococcal Conjugate Immunization in Children

BACKGROUND

Prevention of infections in children vaccinated with 13-valent pneumococcal conjugate vaccine (PCV13) may be less effective against serotype 3 than 19A.

OBJECTIVE

The aim of this study was to to determine differences in IgG and functional antibody for serotype 3 versus 19A following PCV13 immunization, in IgG antibody levels induced by PCV13 compared to naturally-induced immunity, and assess effectiveness of PCV13 against serotype 3 and 19A in prevention of acute otitis media (AOM) and colonization among 6-36-month-old children.

METHODS

Samples were from a prospective, longitudinal, observational cohort study conducted in Rochester, NY. Pneumococcal detection was by culture. 713 serum were tested for antibody levels by enzyme-linked immunosorbent assay, 68 for functional antibody by opsonophagocytosis and 47 for antibody avidity by thiocyanate bond disruption. PCV13 effectiveness in preventing AOM and colonization was determined by comparison of pre-PCV13 detection of serotypes 3 and 19A to post-PCV13.

RESULTS

The proportion of children who reached the antibody threshold of ≧0.35 µg/mL after PCV13 was higher for serotype 19A than serotype 3. Only serotype 19A showed significant increase in PCV13-induced opsonophagocytosis assay titers and antibody avidity. Serotype 3 naturally-induced immune children showed a positive trend of increase in antibody level as children got older, but not PCV13-immunized children. PCV13 effectiveness was not identified in preventing AOM or colonization for serotype 3 but effectiveness of 19A was confirmed.

CONCLUSIONS

PCV13 elicits lower antibody levels and lower effectiveness to serotype 3 versus serotype 19A. Post-PCV13-induced antibody levels for serotype 3 are likely insufficient to prevent AOM and colonization in most young children.

Emerging vaccine strategies against the incessant pneumococcal disease

The incidence of invasive pneumococcal disease (IPD) caused by infection with the pathogen Streptococcus pneumoniae (Spn) has been on a downward trend for decades due to worldwide vaccination programs. Despite the clinical successes observed, the Center for Disease Control (CDC) reports that the continued global burden of S. pneumoniae will be in the millions each year, with a case-fatality rate hovering around 5%. Thus, it is a top priority to continue developing new Spn vaccination strategies to harness immunological insight and increase the magnitude of protection provided. As emphasized by the World Health Organization (WHO), it is also crucial to broaden the implementation of vaccines that are already obtainable in the clinical setting. This review focuses on the immune mechanisms triggered by existing pneumococcal vaccines and provides an overview of the current and upcoming clinical strategies being employed. We highlight the associated challenges of serotype selectivity and using pneumococcal-derived proteins as alternative vaccine antigens.

A randomized, open-label, phase 3 study evaluating safety and immunogenicity of 13-valent pneumococcal conjugate vaccine in Chinese infants and children under 6 years of age

Streptococcus pneumoniae causes a considerable disease burden among children in China. Many isolates exhibit antimicrobial resistance but are often serotypes covered by the 13-valent pneumococcal conjugate vaccine (PCV13). Because the approved infant immunization schedule in China allows PCV13 vaccination only for those 6 weeks to 15 months of age, this phase 3 study was conducted to evaluate PCV13 immunogenicity and safety in unvaccinated older infants and children. Eligible participants were stratified by age into four cohorts: Cohort 1 (n = 125), 6 weeks-2 months; Cohort 2 (n = 354), 7-<12 months; Cohort 3 (n = 250), 1 -<2 years; Cohort 4 (n = 207), 2-<6 years. Cohort 1 received PCV13 at ages 2, 4, and 6 months; older cohorts were randomized 2:1 to PCV13 or Haemophilus influenzae type b (Hib) vaccine using age-appropriate schedules. Within-group immune responses were assessed by immunoglobulin G (IgG) concentrations and opsonophagocytic activity (OPA) titers. Safety evaluations included solicited reactogenicity events and adverse events (AEs). IgG geometric mean concentrations and OPA geometric mean titers for all 13 PCV13 serotypes increased for all participants vaccinated with PCV13, but not those vaccinated with Hib. Immune responses in Cohorts 2-4 were generally comparable with those in Cohort 1 (the infant series) for most serotypes. PCV13 was well tolerated across cohorts, with reported AEs consistent with expectations in these age groups; no new safety signals were identified. These results suggest that PCV13 administered as a catch-up regimen to infants and children 7 months-<6 years of age in China will effectively reduce vaccine-type pneumococcal disease in this population. NCT03574389.

Cost-effectiveness analysis of PCV20 to prevent pneumococcal disease in the Canadian pediatric population

This study assessed the cost-effectiveness of the 20-valent pneumococcal conjugate vaccine (PCV20) in Canadian infants aged <2 years versus the standard of care (SoC), a 13-valent pneumococcal conjugate vaccine (PCV13), or a potential 15-valent pneumococcal conjugate vaccine (PCV15). A decision-analytic Markov model was developed to compare PCV20 with PCV13 or PCV15 in a 2 + 1 schedule over 10 years. Vaccine effect estimates (direct and indirect) across all ages were informed by PCV13 clinical effectiveness and impact studies as well as PCV7 efficacy studies. Epidemiologic, clinical, health state utilities, utility decrements, cost per event, and list price data were from Canadian sources where available. Clinical and economic outcomes related to invasive pneumococcal disease (IPD), hospitalized and non-hospitalized pneumonia, and simple and complex otitis media (OM) were calculated for each strategy. Cost-effectiveness was evaluated from the publicly funded healthcare system perspective. Over 10 years, PCV20 versus PCV13 was estimated to avert over 11,000 IPD cases, 316,000 hospitalized and non-hospitalized pneumonia cases, 335,000 simple and complex OM cases, and 15,000 deaths, resulting in cost savings of over 3.2 billion Canadian dollars (CAD) and 47,000 more quality-adjusted life years (i.e. dominant strategy). Compared with PCV15, PCV20 was estimated to result in over 1.4 billion CAD in cost savings and 21,000 more QALYs (i.e. dominant strategy). PCV20 was dominant over both PCV13 and PCV15. Given broader serotype coverage, substantial incremental benefits and cost-savings, PCV20 should be considered as a replacement for the SoC in the publicly funded Canadian infant immunization program.

Nasopharyngeal Carriage of Pneumococcus in Children in England up to 10 Years After 13-Valent Pneumococcal Conjugate Vaccine Introduction: Persistence of Serotypes 3 and 19A and Emergence of 7C

BACKGROUND

Monitoring changes in pharyngeal carriage of pneumococcus in children following 13-valent pneumococcal conjugate vaccine (PCV13) introduction in the United Kingdom in 2010 informs understanding of patterns of invasive pneumococcal disease (IPD) incidence.

METHODS

Nasopharyngeal swabs from healthy children vaccinated with PCV13 according to schedule (2, 4, and 12 months) were cultured and serotyped. Results for children aged 13-48 months were compared between 2014-2015 and 2017-2019 and with children aged 6-12 months (2017-2020). Blood was obtained from a subset of children for pneumococcal serotype-specific immunoglobulin G (IgG).

RESULTS

Total pneumococcal carriage at 13-48 months was 47.9% (473/988) in 2014-2015 and 51.8% (412/795) in 2017-2019 (P = .10); at age 6-12 months this value was 44.6% (274/615). In 2017-2019, 2.9% (95% confidence interval, 1.8%-4.3%) of children aged 13-48 months carried PCV13 serotypes (mainly 3 [1.5%] and 19A [0.8%]) and >20% carried the additional 20-valent PCV (PCV20) serotypes. Similar proportions of children had IgG ≥0.35 IU/mL for each serotype in 2014-2015 and 2017-2019. Serotype 7C carriage increased significantly (P < .01) between 2014-2015 and 2017-2019. Carriage of PCV20 serotypes 8 and 12F, both major causes of IPD, was rare.

CONCLUSIONS

Introduction of PCV20, if licensed for children, could significantly change the composition of pneumococcal serotypes carried in the pharynx of UK children.

CLINICAL TRIALS REGISTRATION

NCT03102840.

Synergistic Protection against Secondary Pneumococcal Infection by Human Monoclonal Antibodies Targeting Distinct Epitopes

Streptococcus pneumoniae persists as a leading cause of bacterial pneumonia despite the widespread use of polysaccharide-based vaccines. The limited serotype coverage of current vaccines has led to increased incidence of nonvaccine serotypes, as well as an increase in antibiotic resistance among these serotypes. Pneumococcal infection often follows a primary viral infection such as influenza virus, which hinders host defense and results in bacterial spread to the lungs. We previously isolated human monoclonal Abs (mAbs) against the conserved surface Ag pneumococcal histidine triad protein D (PhtD), and we demonstrated that mAbs to this Ag are protective against lethal pneumococcal challenge prophylactically and therapeutically. In this study, we elucidated the mechanism of protection of a protective anti-pneumococcal human mAb, PhtD3, which is mediated by the presence of complement and macrophages in a mouse model of pneumococcal infection. Treatment with mAb PhtD3 reduced blood and lung bacterial burden in mice, and mAb PhtD3 is able to bind to bacteria in the presence of the capsular polysaccharide, indicating exposure of surface PhtD on encapsulated bacteria. In a mouse model of secondary pneumococcal infection, protection mediated by mAb PhtD3 and another mAb targeting a different epitope, PhtD7, was reduced; however, robust protection was restored by combining mAb PhtD3 with mAb PhtD7, indicating a synergistic effect. Overall, these studies provide new insights into anti-pneumococcal mAb protection and demonstrate, to our knowledge, for the first time, that mAbs to pneumococcal surface proteins can protect against secondary pneumococcal infection in the mouse model.

Pathogenesis of Streptococcus pneumoniae serotype 3 during natural colonization and infections among children and its IgG correlate of protection in a mouse model

Current licensed pneumococcal conjugate vaccines (PCVs) are effective against pneumococcal diseases caused by the serotypes contained in the PCvs However; several studies evaluating pneumococcal colonization and acute otitis-media (AOM) prevention in young children vaccinated with PCV13, observed less effectiveness against serotype-3. One possible reason for less effectiveness may be release of the capsular polysaccharide (CPS) of serotype-3 (CPS-3) as an immune evasion mechanism. Here we evaluated free CPS-3 levels released from 6 clinical isolates from young children compared to WU2 strain and to serotype-19A CPS (CPS-19A) released in vitro when interacting with nasopharyngeal, middle-ear and lung cell-lines. Clinical serotype-3 strains showed greater release of CPS than WU2 with the interaction to 2 cell-lines and all 6 clinical serotype-19A strains. We next evaluated CPS-3 vs CPS-19A levels in middle-ear fluid (MEF) and the nasopharynx (NP) of young children and found higher levels of CPS-3 compared to CPS-19A in MEF during AOM but not in NP secretions during colonization. With anti-CPS-3 IgG in MEF and NP secretions at time of health and onset of AOM, a significant negative correlation (r = -0.75, p < 0.05) between unbound anti-CPS-3 IgG levels and free- anti-CPS-3 in MEF were found, and a significant lower detection of unbound anti-CPS-3 IgG in NP at the time of health with serotype-3 SPN (p < 0.05) compared to irrelevant SPN serotypes were found. In a mouse model of AOM and pneumonia, we sought a correlate of protection against serotype-3 infection using human serum-derived anti-CPS-3 IgG. We conclude that serotype-3 clinical isolates from children release more capsule than WU2 strains or 19A strains during in vitro testing; release more capsule in the MEF of children during AOM than serotype 19A; unbound anti-CPS-3 IgG levels negatively correlate with free-anti-CPS-3; and a level of 2.8 µg/ml anti-CPS-3 antibody protects mice from AOM and pneumonia but not colonization.

Pneumococcal vaccination uptake and missed opportunities for vaccination among Canadian adults: A cross-sectional analysis of the Canadian Longitudinal Study on Aging (CLSA)

Introduction

In Canada, pneumococcal vaccination is recommended to all adults aged ≥65 and those <65 who have one or more chronic medical conditions (CMCs). Understanding vaccine uptake and its determinants among eligible groups has important implications for reducing the burden of pneumococcal disease.

Methods

Using data from a large national cohort of Canadian residents aged ≥47 years between 2015–2018, we calculated self-reported pneumococcal vaccine uptake among eligible groups, estimated associations between key factors and non-vaccination, assessed missed opportunities for vaccination (MOV) and examined risk factors for MOV. Adjusted odds ratios (aORs) and 95% confidence intervals (CIs) for relevant associations were estimated through logistic regression.

Results

45.8% (95% CI: 45.2–46.5) of 22,246 participants aged ≥65 and 81.3% (95% CI: 80.5–82.0) of 10,815 individuals aged 47–64 with ≥1 CMC reported never having received a pneumococcal vaccine. Receipt of influenza vaccination in the previous year was associated with the lowest odds of pneumococcal non-vaccination (aOR = 0.14 [95% CI: 0.13–0.15] for older adults and aOR = 0.23 [95% CI: 0.20–0.26] for those aged 47–64 with ≥1 CMC). Pneumococcal vaccine uptake was also more likely in case of contact with a family doctor in the previous year (versus no contact), increased with age and varied widely across provinces. Among individuals recently vaccinated against influenza, 32.6% (95% CI: 31.9–33.4) of those aged ≥65 and 71.1% (95% CI: 69.9–72.3) of those aged 47–64 with ≥1 CMC missed an opportunity to get a pneumococcal vaccine. Among individuals who had contact with a family doctor, 44.8% (95% CI: 44.1–45.5) of those aged ≥65 and 80.4% (95% CI: 79.6–81.2) of those aged 47–64 with ≥1 CMC experienced a MOV.

Conclusions

Pneumococcal vaccine uptake remains suboptimal among at-risk Canadian adults who are eligible for vaccination. Further research is needed to clarify the reasons behind missed opportunities for vaccination and adequately address the main barriers to pneumococcal vaccination.

Invasive pneumococcal disease and long-term outcomes in children: A 20-year population cohort study

Background

Although vaccination against Streptococcus pneumoniae infections (such as invasive pneumococcal disease (IPD)) are available, challenges remain in prevention efforts. Moreover, downstream sequelae in children is relatively unknown. Thus, we aimed to evaluate short and long-term health outcomes among children with IPD.

Methods

Analysis of Streptococcus pneumoniae positive isolates from sterile body sites in children (0-17 years) in Alberta (Canada) from 1999 to 2019 was performed retrospectively (n=888). Cases were age and sex-matched to hospitalized population controls. Linkage to administrative health datasets was done to determine comorbidities and healthcare related outcomes. Cox proportional hazards were used to assess differences in time to mortality and hospitalisation between cases and controls in short (<30-day), intermediate (30-90 day), long-term (>90-day) follow-up.

Findings

Proportionally more deaths occurred in cases (4.8 deaths/1000 person-years (PY)) than controls (2.7 deaths/1000 PY), leading to a significant adjusted hazard ratio (aHR) of 1.80 (95% CI 1.22-2.64). This increased risk of death was influenced primarily by short-term mortality (319 vs 36 deaths/1000 PY in cases vs controls respectively, aHR 8.78 [95% CI 3.33-23.18]), as no differences were seen in intermediate (14 vs 7 deaths/1000 PY; aHR 2.03, 95% CI 0.41-10.04) or long-term time intervals (2.4 vs 2.3 deaths/1000 PY, aHR 1.03, 95% CI 0.63-1.69).

Interpretation

IPD continues to negatively impact survival in children despite vaccination. Although long-term impact on mortality and hospitalisations may not be substantial, the immediate effects of IPD are significant.

Funding

This work was supported by grants-in-aid from Pfizer Canada and Wyeth Canada Inc all to GJT.

A Nonadjuvanted Whole-Inactivated Pneumococcal Vaccine Induces Multiserotype Opsonophagocytic Responses Mediated by Noncapsule-Specific Antibodies

Streptococcus pneumoniae (Spn) remains a major cause of global mortality, with extensive antigenic diversity between capsular serotypes that poses an ongoing challenge for vaccine development. Widespread use of pneumococcal conjugate vaccines (PCVs) targeting Spn capsules has greatly reduced infections by vaccine-included serotypes but has led to increased infections by nonincluded serotypes. To date, high cost of PCVs has also limited their usefulness in low-income regions where disease burdens are highest. To overcome these limitations, serotype-independent vaccines are being actively researched. We have developed a whole-cell gamma-irradiated Spn vaccine (termed Gamma-PN) providing serotype-independent protection. We demonstrate that Gamma-PN immunization of mice or rabbits via the clinically relevant intramuscular route induces protein-specific antibodies able to bind numerous nonvaccine encapsulated serotypes, which mediate opsonophagocytic killing and protection against lethal challenges. Gamma-PN induced comparable or superior opsonophagocytic killing assay (OPKA) responses in rabbits to the licensed Prevnar 13 vaccine (PCV13) for vaccine-included serotypes, and a superior response to nonincluded serotypes, including emergent 22F and 35B. Additionally, despite a lower observed reactogenicity, administration of Gamma-PN without adjuvant resulted in higher OPKA responses and improved protection compared to adjuvanted Gamma-PN. To our knowledge, this has not been demonstrated previously for a whole-inactivated Spn vaccine. Eliminating the requirement for adjuvant comes with numerous benefits for clinical applications of this vaccine and poses interesting questions for the inclusion of adjuvant in similar vaccines in development.

Healthcare Costs for Pneumococcal Disease in the Era of Infant Immunization With 13-Valent Pneumococcal Conjugate Vaccine: A Population-Based Study

OBJECTIVES

Invasive pneumococcal disease (IPD) and a variety of clinical syndromes caused by pneumococci, such as acute otitis media (AOM), acute sinusitis (AS), and community-acquired pneumonia (CAP), cause a substantial burden on healthcare systems. Few studies have explored the short-term financial burden of pneumococcal disease after the 13-valent pneumococcal conjugate vaccine (PCV13) introduction in the infant immunization programs. This population-based study evaluated changes in costs associated with healthcare utilization for pneumococcal disease after the PCV13 introduction in the infant immunization program in British Columbia, Canada.

METHODS

Individuals with pneumococcal disease were identified using provincial administrative data for the 2000 to 2018 period. Total direct healthcare costs were determined using case-mix methodology for hospitalization and fee-for-service codes for outpatient visits and medications dispensed. Costs were adjusted to 2018 Canadian dollars. Changes in the annual healthcare costs were evaluated across vaccine eras (pre-PCV13, 2000-2010; PCV13, 2011-2018) using generalized linear models, adjusting for the 7-valent pneumococcal conjugate vaccine program (2004-2010).

RESULTS

During the 19-year study period, pneumococcal disease resulted in 6.3 million cases among 85 million total patient-years, resulting in total healthcare costs of $7.9 billion. More than 6.2 million cases were treated in outpatient setting, costing $0.65 billion (8% of total costs associated with pneumococcal disease treatment), whereas 370 000 hospitalized cases were 3% of all cases, which accrued $7.25 billion (92% of total costs) in costs. Healthcare costs for all studied infections nearly doubled over the study period from $248 million in 2000 to $476 million in 2018 (P = .003). In contrast, there were large declines in total annual costs in the PCV13 era for IPD (adjusted relative rate (aRR) 0.73; 95% confidence interval [CI] 0.56-0.95; P = .032), AOM (aRR 0.70; 95% CI 0.59-0.83; P = .001), and AS (aRR 0.68; 95% CI 0.54-0.85; P = .004) compared with the pre-PCV13 era. Total costs increased marginally in the PCV13 era for all-cause CAP (aRR 1.04; 95% CI 0.94-1.15; P = .484).

CONCLUSIONS

This study confirms a temporal association in declining economic burden for IPD, AOM, and AS after the PCV13 introduction. Nevertheless, the total economic burden continues to be high in the PCV13 era, mainly driven by increasing CAP costs.

Invasive Pneumococcal Disease and Long-Term Mortality Rates in Adults, Alberta, Canada

The relationship between increased short-term mortality rates after invasive pneumococcal disease (IPD) has been frequently studied. However, the relationship between IPD and long-term mortality rates is unknown. IPD patients in Alberta, Canada, had clinical data collected that were linked to administrative databases. We used Cox proportional hazards modeling, and the primary outcome was time to all-cause deaths. First IPD events were identified in 4,522 patients, who had a median follow-up of 3.2 years (interquartile range 0.8‒9.1 years). Overall all-cause mortality rates were consistently higher among cases than controls at 30 days (adjusted hazard ratio [aHR] 3.75, 95% CI 3.29–4.28), 30‒90 days (aHR 1.56, 95% CI 1.27‒1.93), and >90 days (aHR 1.43, 95% CI 1.33–1.54). IPD increases risk for short, intermediate, and long-term mortality rates regardless of age, sex, or concurrent conditions. These findings can help clinicians focus on postdischarge patient plans to limit long-term effects after acute IPD infection.

Understanding predictors of pneumococcal vaccine uptake in older adults aged 65 years and older in high-income countries across the globe: A scoping review

BACKGROUND

Pneumococcal disease causes substantial morbidity and mortality in older adults. Pneumococcal polysaccharide vaccine (PPV23) is routinely recommended to reduce the disease burden in this population. However, the vaccination coverage in older adults remains suboptimal in high-income countries.

OBJECTIVES

We sought to understand the current landscape of published literature on the predictors of pneumococcal vaccine uptake in older adults aged 65 years and older in high-income countries, and to identify the gaps in literature to inform future research.

METHODS

We conducted a scoping review employing the Arksey and O'Malley framework and Joanna Briggs Methods. We searched Medline, EMBASE, CINAHL, PsycInfo and Cochrane databases. We included quantitative and qualitative studies on predictors of pneumococcal vaccination in older adults that reported older adult- and pneumococcal vaccine-specific results, conducted in high-income settings, and published in English between January 2015 and April 2020. We excluded studies assessing interventions to improve vaccine uptake. We followed the Strategic Advisory Group of Experts on Immunization Working Group Vaccine Hesitancy Determinants Matrix to map the predictors within contextual, individual and social group, and vaccine and vaccination-specific influence determinants. Studies on providers and institutions were also included and results summarized separately.

RESULTS

We included 52 publications in our review. Most of the predictors in 39 quantitative studies belonged to the individual and social group influences (n = 12), followed by contextual influences (n = 11) and vaccine and vaccination-specific issues (n = 3). Few qualitative studies explored the barriers to pneumococcal vaccination. Only five studies examined predictors from the healthcare providers' perspective. Three studies examined the institutional characteristics as the predictors of pneumococcal vaccination in older adults.

CONCLUSIONS

We identified enablers and barriers of pneumococcal vaccination among older adults in high-income settings. We also identified gaps in the literature and provide recommendations for future research to address the gaps.

Safety and Immunogenicity of V114, a 15-valent Pneumococcal Conjugate Vaccine, Compared With 13- valent Pneumococcal Vaccine in Japanese Adults Aged ≥65 Years: Subgroup Analysis of a Randomized Phase III Trial (PNEU-AGE)

The safety and immunogenicity of V114, a 15-valent pneumococcal conjugate vaccine (PCV), was assessed in a pivotal Phase III trial in healthy adults ≥50 years of age (NCT03950622, Japic-CTI 194845). We report a subgroup analysis of 245 Japanese participants (all ≥65 years of age). Participants were randomized 1:1 to receive a single dose of V114 or 13-valent PCV (PCV13). Immune responses were evaluated at baseline and 30 days post-vaccination. Non-serious and serious adverse events (AEs) were evaluated post-vaccination through 14 days and 6 months, respectively. Proportions of participants experiencing solicited and serious AEs were comparable for both vaccines; all solicited AEs were mild or moderate in severity. Serotype-specific opsonophagocytic activity (OPA) geometric mean titers at 30 days post-vaccination were comparable between groups for all 13 shared serotypes and higher with V114 for the unique serotypes 22F and 33F. Proportions of participants with a ≥4-fold rise in serotype-specific OPA responses from pre-vaccination to 30 days post-vaccination were higher with V114 than PCV13 for serotypes 3, 22F, and 33F. V114 was well tolerated and immunogenic in Japanese adults ≥65 years of age, with safety and immunogenicity profiles consistent with that seen in the overall study population.

Estimating population-based incidence of community-acquired pneumonia and acute otitis media in children and adults in Ontario and British Columbia using health administrative data, 2005-2018: a Canadian Immunisation Research Network (CIRN) study

BACKGROUND

There is a paucity of data on the burden of the full spectrum of community-acquired pneumonia (CAP) and acute otitis media (AOM) from outpatient and inpatient settings across the age spectrum.

METHODS

We conducted a population-based retrospective study in Ontario and British Columbia (BC), Canada, to estimate the incidence rate of CAP and AOM in children and adults over a 14-year period using health administrative databases. CAP and AOM cases were identified from outpatient physician consultation and hospitalisation data in both provinces, and from emergency department visit data in Ontario.

RESULTS

During 2005-2018, Ontario had 3 607 124 CAP, 172 290 bacterial CAP, 7814 pneumococcal pneumonia, and 8 026 971 AOM cases. The incidence rate of CAP declined from 3077/100 000 in 2005 to 2604/100 000 in 2010 before increasing to 2843/100 000 in 2018; bacterial CAP incidence rate also declined from 178/100 000 in 2005 to 112/100 000 in 2010 before increasing to 149/100 000 in 2018. The incidence rate of AOM decreased from 4192/100 000 in 2005 to 3178/100 000 in 2018. BC had 970 455 CAP, 317 913 bacterial CAP, 35 287 pneumococcal pneumonia and 2 022 871 AOM cases. The incidence rate of CAP in BC decreased from 2214/100 000 in 2005 to 1964/100 000 in 2010 before increasing to 2176/100 000 in 2018; bacterial CAP incidence rate increased from 442/100 000 in 2005 to 981/100 000 in 2018. The incidence rate of AOM decreased from 3684/100 000 in 2005 to 2398/100 000 in 2018. The incidence rate of bacterial CAP increased with age in older adults (≥65 years) with the highest burden in the oldest cohort aged ≥85 years both before and after 13-valent pneumococcal conjugate vaccine (PCV13) programme in both provinces. Hospitalised pneumococcal pneumonia decreased slightly but non-hospitalised pneumococcal pneumonia increased in BC during PCV13 period. No consistent direct benefit of PCV13 on CAP was observed in the paediatric population.

CONCLUSIONS

There is a substantial burden of CAP and AOM in Ontario and BC. Indirect benefits from childhood PCV vaccination and polysaccharide vaccination of older adults have not substantially decreased the burden of pneumococcal pneumonia in older adults.

Naturally acquired antibodies against 7 Streptococcus pneumoniae serotypes in Indigenous and non-Indigenous adults

Despite the use of pneumococcal conjugate vaccines for pediatric immunization, North American Indigenous populations continue to experience high burden of pneumococcal infections. Naturally acquired antibodies, which can protect unvaccinated adults against pneumococcal infections, have not previously been studied in Canadian Indigenous people. We analysed concentrations of natural serum IgG, IgM and IgA antibodies specific to 7 serotype-specific capsular polysaccharides (3, 6B, 9V, 14, 19A, 19F and 23F) in 141 healthy individuals (age between 18 and 80 years), including Indigenous adults living in 2 geographical different areas of Ontario, Canada, and non-Indigenous residing in northwestern Ontario. Regardless of the geographical area, concentrations of IgG specific to serotypes 6B, 9V, and 14, IgM specific to 9V, and all serotype-specific IgA were significantly higher in Indigenous study participants as compared to non-Indigenous. The differences are likely attributed to an increased exposure of Indigenous individuals to Streptococcus pneumoniae and/or cross-reactive antigens of other microorganisms or plants present in the environment. Although in non-Indigenous adults concentrations of IgM specific to 9V, 19A, 19F, and 23F significantly decreased with age, this was not observed in Indigenous individuals suggesting that Indigenous people may experience continuous exposure to pneumococci and cross-reactive antigens over the life span. Women had generally higher concentrations of natural IgG and IgM concentrations than men, with more striking differences found in Indigenous adults, potentially associated with larger exposure of women to young children, the major reservoir of pneumococci in communities. Our data suggest that increased rates of pneumococcal infections among Indigenous people are unlikely related to deficiency of naturally acquired antibodies, at least those specific to 7 common serotypes. Determining serological correlates of protection for adults will be essential to identify the groups in need of adult pneumococcal immunizations that may prevent excessive burden of the disease among North American Indigenous people.

Safety and immunogenicity of V114, a 15-valent pneumococcal conjugate vaccine, in adults living with HIV

OBJECTIVES

To evaluate safety and immunogenicity of V114 [15-valent pneumococcal conjugate vaccine (PCV) containing serotypes 1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, 22F, 23F, and 33F], followed by 23-valent pneumococcal polysaccharide vaccine (PPSV23) 8 weeks later, in adults living with HIV.

DESIGN

In this phase 3 study (V114-018; NCT03480802), pneumococcal vaccine-naive adults with HIV (CD4+ cell count ≥50 cells/μl, plasma HIV RNA <50 000 copies/ml, receiving antiretroviral therapy) were randomized 1 : 1 to receive one dose of V114 or licensed 13-valent PCV (PCV13) on day 1; participants received PPSV23 at week 8.

METHODS

Adverse events and serotype-specific opsonophagocytic activity (OPA) and immunoglobulin G (IgG) antibodies were evaluated after each vaccination.

RESULTS

Of 302 participants enrolled, 292 (96.7%) completed the study. Proportions of participants experiencing at least one adverse event were 73.0 and 62.7% in the V114 and PCV13 groups following PCV and 60.7 and 71.6% following PPSV23. Most solicited adverse events were of mild or moderate severity and short duration. OPA geometric mean titers (GMTs) and IgG geometric mean concentrations (GMCs) were generally comparable between groups for shared serotypes at day 30 and maintained at week 12. OPA and IgG responses for additional serotypes in V114 (22F, 33F) were higher following V114 than PCV13 at day 30 but comparable at week 12, 30 days post-PPSV23.

CONCLUSION

In pneumococcal vaccine-naive adults living with HIV, V114 was well tolerated and induced immune responses for all 15 pneumococcal serotypes. V114 can be followed by PPSV23 8 weeks later to broaden serotype coverage.

Fatal Pediatric Streptococcal Infection: A Clinico-Pathological Study

PURPOSE AND CONTEXT

Streptococcal Infection (SI) is an important cause of pediatric death in children, yet limited reports exist on autopsy findings in fatal SI cases.

METHOD

Case records (1997-2019) of SI with no pre-existing risk factors were reviewed and selected. Their clinical and pathological findings in the autopsy reports were analyzed.

RESULTS

In our cohort of 38 cases based on bacterial culture results, SI was most commonly caused by Streptococcus pneumoniae (SPn; 45%) and Streptococcus pyogenes (SPy; 37%). 92% of decedents had some prodromal symptoms prior to terminal presentation. The clinical course was often rapid, with 89% found unresponsive, suddenly collapsing, or dying within 24 hours of hospital admission. 64% of deaths were attributed to sepsis, more frequently diagnosed in the SPy group than in the SPn group (71% vs 48%). Pneumonia was found in both SPn and SPy groups, whereas meningitis was exclusively associated with SPn.

CONCLUSION

Our study shows fatal SI is most commonly caused by either SPn or SPy, both of which are frequently associated with prodromal symptoms, rapid terminal clinical course, and evidence of sepsis. Postmortem diagnosis of sepsis is challenging and should be correlated with clinical features, bacterial culture results, and autopsy findings.

Serotypes and Clonal Composition of Streptococcus pneumoniae Isolates Causing IPD in Children and Adults in Catalonia before 2013 to 2015 and after 2017 to 2019 Systematic Introduction of PCV13

The goal of this study was to investigate the distribution of serotypes and clonal composition of Streptococcus pneumoniae isolates causing invasive pneumococcal disease (IPD) in Catalonia, before and after systematic introduction of PCV13. Pneumococcal strains isolated from normally sterile sites obtained from patients of all ages with IPD received between 2013 and 2019 from 25 health centers of Catalonia were included. Two study periods were defined: presystematic vaccination period (2013 and 2015) and systematic vaccination period (SVP) (2017 to 2019). A total of 2,303 isolates were analyzed. In the SVP, there was a significant decrease in the incidence of IPD cases in children 5 to 17 years old (relative risk [RR] 0.61; 95% confidence interval [CI] 0.38 to 0.99), while there was a significant increase in the incidence of IPD cases in 18- to 64-year-old adults (RR 1.33; 95% CI 1.16 to 1.52) and adults over 65 years old (RR 1.23; 95% CI 1.09 to 1.38). Serotype 8 was the major emerging serotype in all age groups except in 5- to 17-year-old children. In children younger than 5 years old, the main serotypes in SVP were 24F, 15A, and 3, while in adults older than 65 years they were serotypes 3, 8, and 12F. A significant decrease in the proportions of clonal complexes CC156, CC191, and ST306 and an increase in those of CC180, CC53, and CC404 were observed. A steady decrease in the incidence of IPD caused by PCV13 serotypes indicates the importance and impact of systematic vaccination. The increase of non-PCV13 serotypes highlights the need to expand serotype coverage in future vaccines and rethink vaccination programs for older adults.

IMPORTANCE We found that with the incorporation of the PCV13 vaccine, the numbers of IPD cases caused by serotypes included in this vaccine decreased in all of the age groups. Still, there was an unforeseen increase of the serotypes not included in this vaccine causing IPD, especially in the >65-year-old group. Moreover, a significant increase of serotype 3 included in the vaccine has been observed; this event has been reported by other researchers. These facts call for the incorporation of more serotypes in future vaccines and a more thorough surveillance of the dynamics of this microorganism.

Isolation and Characterization of Human Monoclonal Antibodies to Pneumococcal Capsular Polysaccharide 3

The current pneumococcal capsular polysaccharide (PPS) conjugate vaccine (PCV13) is less effective against Streptococcus pneumoniae serotype 3 (ST3), which remains a major cause of pneumococcal disease and mortality. Therefore, dissecting structure-function relationships of human ST3 pneumococcal capsular polysaccharide (PPS3) antibodies may reveal characteristics of protective antibodies. Using flow cytometry, we isolated PPS3-binding memory B cells from pneumococcal vaccine recipients and generated seven PPS3-specific human monoclonal antibodies (humAbs). Five humAbs displayed ST3 opsonophagocytic activity, four induced ST3 agglutination in vitro, and four mediated both activities. Two humAbs, namely, C10 and C27, that used the same variable heavy (VH) and light (VL) chain domains (VH3-9*01/VL2-14*03) both altered ST3 gene expression in vitro; however, C10 had fewer VL somatic mutations, higher PPS3 affinity, and promoted in vitro ST3 opsonophagocytic and agglutinating activity, whereas C27 did not. In C57BL/6 mice, both humAbs reduced nasopharyngeal colonization with ST3 A66 and a clinical strain, B2, and prolonged survival following lethal A66 intraperitoneal infection, but only C10 protected against lethal intranasal infection with the clinical strain. After performing VL swaps, C10VH/C27VL exhibited reduced ST3 binding and agglutination, but C27VH/C10VL binding was unchanged. However, both humAbs lost the ability to reduce colonization in vivo when their light chains were replaced. Our findings associate the ability of PPS3-specific humAbs to reduce colonization with ST3 agglutination and opsonophagocytic activity, and reveal an unexpected role for the VL in their functional activity in vitro and in vivo. These findings also provide insights that may inform antibody-based therapy and identification of surrogates of vaccine efficacy against ST3. IMPORTANCE Despite the global success of vaccination with pneumococcal conjugate vaccines, serotype 3 (ST3) pneumococcus remains a leading cause of morbidity and mortality. In comparison to other vaccine-included serotypes, the ST3 pneumococcal capsular polysaccharide (PPS3) induces a weaker opsonophagocytic response, which is considered a correlate of vaccine efficacy. Previous studies of mouse PPS3 monoclonal antibodies identified ST3 agglutination as a correlate of reduced ST3 nasopharyngeal colonization in mice; however, neither the agglutinating ability of human vaccine-elicited PPS3 antibodies nor their ability to prevent experimental murine nasopharyngeal colonization has been studied. We generated and analyzed the functional and in vivo efficacy of human vaccine-elicited PPS3 monoclonal antibodies and found that ST3 agglutination associated with antibody affinity, protection in vivo, and limited somatic mutations in the light chain variable region. These findings provide new insights that may inform the development of antibody-based therapies and next-generation vaccines for ST3.

Population-based incidence of invasive pneumococcal disease in children and adults in Ontario and British Columbia, 2002-2018: A Canadian Immunization Research Network (CIRN) study

BACKGROUND

Invasive pneumococcal disease (IPD) burden, evaluated in Canada using reported confirmed cases in surveillance systems, is likely underestimated due to underreporting. We estimated the burden of IPD in Ontario and British Columbia (BC) by combining surveillance data with health administrative databases.

METHODS

We established a cohort of 27,525 individuals in Ontario and BC. Laboratory-confirmed IPD cases were identified from Ontario's integrated Public Health Information System and the BC Centre for Disease Control Public Health Laboratory. Possible IPD cases were identified from hospitalization data in both provinces, and from emergency department visit data in Ontario. We estimated the age and sex adjusted annual incidence of IPD and pneumococcal conjugate/polysaccharide vaccine (PCV/PPV) serotype-specific IPD using Poisson regression models.

RESULTS

In Ontario, 20,205 overall IPD cases, including 15,299 laboratory-confirmed cases, were identified with relatively stable age- and sex-adjusted annual incidence rates ranging from 13.7/100,000 (2005) to 13.6/100,000 (2018). In BC, 7,320 overall IPD cases, including 5,932 laboratory-confirmed cases were identified; annual incidence rates increased from 10.9/100,000 (2002) to 13.2/100,000 (2018). Older adults aged ≥ 85 years had the highest incidence rates. During 2007-2018 the incidence of PCV7 serotypes and additional PCV13 serotypes decreased while the incidence of unique PPV23 and non-vaccine serotypes increased in both provinces.

CONCLUSIONS

IPD continues to cause a substantial public health burden in Canada despite publicly funded pneumococcal vaccination programs, resulting in part from an increase in unique PPV23 and non-vaccine serotypes.

The application value of metagenomic next-generation sequencing in children with invasive pneumococcal disease

BACKGROUND

A retrospective analysis was conducted to explore the sensitivity and specificity of metagenomic next-generation sequencing (mNGS) in blood, cerebrospinal fluid, and pleural effusion samples in children with invasive pneumococcal disease (IPD), and the impact of detection timing on prognosis and cost.

METHODS

Children with IPD admitted to Hebei Children's Hospital from 1 January 2017 to 1 March 2021 were allocated to 1 of 3 groups according to the clinical symptoms and lesions (Group 1: bacteremia; Group 2: meningitis; Group 3: pleurisy). Taking Alere BinaxNow^® Streptococcus pneumoniae (S. pneumoniae) antigen detection and blood culture as the gold standard, receiver operating characteristic (ROC) was used to establish the diagnostic value of mNGS.

RESULTS

A total of 96 cases were enrolled in the study, comprising Group 1 (n=65), Group 2 (n=17), and Group 3 (n=14). The positive rate of mNGS test was 62.5% (n=60), and the total coincidence rate was 75.0%. Delayed mNGS was found to have no significant effect on the 30-day survival rate; however, the species-specific read number (SSRN) of S. pneumoniae detected by mNGS in the early stage of the disease was higher, and it could significantly reduce the hospitalization days and costs (P<0.05).

CONCLUSIONS

The sensitivity and specificity of mNGS are high in the identification of S. pneumoniae in blood, cerebrospinal fluid, and pleural effusion samples, and the SSRN of S. pneumoniae is related to the interval from onset to sample collection. Early mNGS detection has no significant effect on the 30-day survival rate among children with IPD, but it can reduce hospitalization costs and duration.

Effectiveness of the 13-Valent Pneumococcal Conjugate Vaccine on Invasive Pneumococcal Disease in Greenland

The 13-valent pneumococcal conjugate vaccine (PCV13) was introduced in 2010 to the childhood vaccination program in Greenland. This study aimed to estimate the effectiveness of the PCV13 on the incidence of invasive pneumococcal disease (IPD) in children and in adults in Greenland. IPD cases from the pre-PCV13 period (January 1995-September 2010) were compared with the post-PCV13 period (September 2010-October 2020). Register data were collected from laboratory records, IPD reports, the national registry on admissions, and medical files. A total of 295 IPD cases were identified in the study period. Overall IPD incidence rate (IR) declined from the pre-PCV13 period to the post-PCV13 period (IR 23.3 to 15.3 per 100,000 person years). Overall IPD incidence among children decreased significantly, whereas overall IPD incidence among the elderly increased significantly. During the post-PCV13 period, the incidence of vaccine serotype (VT) IPD decreased in all ages, while the incidence of non-vaccine serotype (NVT) IPD increased. This increase was most substantial among elderly ≥60 years. In conclusion, the PCV13 has reduced incidence rates of IPD in Greenland. However, the increase in NVT IPD among the elderly is noteworthy, and sup-ports continued surveillance of IPD in the population of Greenland.

Stable Incidence of Invasive Pneumococcal Disease in Children in Northern France From 2014 Through 2018

BACKGROUND

The 13-valent pneumococcal conjugate vaccine (PCV13) has been recommended in France since June 2010. The aim of this study was to evaluate the trends in the incidence of invasive pneumococcal disease (IPD) resulting in hospitalization of children younger than 18 years of age, to identify the vaccination status of these patients and to analyze the serotypic evolution of the pneumococci involved in the various types of IPD.

METHODS

This multicenter retrospective study reviewed all admissions of children younger than 18 years of age for IPD from 2014 through 2018 in all hospitals with a pediatric or neonatal unit in northern France. Data completeness was obtained by matching 3 independent databases. The incidence of IPD resulting in hospitalization was calculated per age group. The clinical course and the vaccine and nonvaccine types were described overall and by the IPD type.

RESULTS

One hundred thirty cases of IPD were identified: 51 with bacteremia, 45 meningitis, 28 pneumonia or pleuropneumonia and 6 arthritis. The IPD incidence ranged from 2.4 to 3.0/100,000 in children under 18 years of age (95% confidence intervals, 1.4-3.3 and 1.9-4.1, respectively), and from 9.5 to 15.9/100,000 in children under 2 years of age, with no significant differences over time. Nonvaccine types were predominant (81%), mainly 24F, 23B and 10A. Vaccine serotype 3 was involved in 10 cases of IPD, 2 of which were in correctly vaccinated children. Two cases of IPD could have been prevented by vaccination. Neurologic sequelae affected 26% of these children (62% of those with meningitis). Six children died from IPD (5%).

CONCLUSION

The incidence of IPD resulting in hospitalization remained stable in northern France during the study period, with no significant increase in nonvaccine types. Further surveillance is needed to adjust the vaccination strategy if necessary.

Invasive pneumococcal disease caused by serotypes 22F and 33F in Canada: the SAVE study 2011-2018

A 15-valent conjugate vaccine that provides protection against Streptococcus pneumoniae serotypes 22F and 33F is in development. Here we report on the prevalence, antimicrobial susceptibility, and clonal structure of these serotypes in Canada. From 2011 to 2018, the SAVE study collected 11,044 invasive S. pneumoniae isolates. Of these, 9.3% (1024/11,044) and 3.8% (416/11,044) were 22F and 33F, respectively. Serotype 22F isolates were susceptible to most antimicrobials tested except clarithromycin, where susceptibility significantly decreased over time (2011: 80.4%, 2018: 52.9%, P < 0.0001). Only 1.6% of serotype 22F isolates were multidrug-resistant (MDR), while 96% of typed strains were clonal cluster (CC) 433. Serotype 33F isolates demonstrated low susceptibility to clarithromycin and trimethoprim/sulfamethoxazole (22.4% and 24.6%, respectively) and 4.8% MDR. Most serotype 33F isolates were CC100, CC673 and CC717. CC100 prevalence increased significantly over time (2011: 50.0%, 2018: 84.8%, P < 0.006). Continued surveillance of these serotypes is crucial to identify further changes in prevalence, antimicrobial susceptibility, and clonal spread.

A Structural Model for the Ligand Binding of Pneumococcal Serotype 3 Capsular Polysaccharide-Specific Protective Antibodies

Capsular polysaccharides (CPSs) are major virulence factors that decorate the surfaces of many human bacterial pathogens. In their pure form or as glycoconjugate vaccines, CPSs are extensively used in vaccines deployed in clinical practice worldwide. However, our understanding of the structural requirements for interactions between CPSs and antibodies is limited. A longstanding model based on comprehensive observations of antibody repertoires binding to CPSs is that antibodies expressing heavy chain variable gene family 3 (VH3) predominate in these binding interactions in humans and VH3 homologs in mice. Toward understanding this highly conserved interaction, we generated a panel of mouse monoclonal antibodies (MAb) against Streptococcus pneumoniae serotype 3 CPS, determined an X-ray crystal structure of a protective MAb in complex with a hexasaccharide derived from enzymatic hydrolysis of the polysaccharide, and elucidated the structural requirements for this binding interaction. The crystal structure revealed a binding pocket containing aromatic side chains, suggesting the importance of hydrophobicity in the interaction. Through mutational analysis, we determined the amino acids that are critical in carbohydrate binding. Through elucidating the structural and functional properties of a panel of murine MAbs, we offer an explanation for the predominant use of the human VH3 gene family in antibodies against CPSs with implications in knowledge-based vaccine design.

Changes in the Management of Severe Orbital Infections Over Seventeen Years

OBJECTIVES

Periorbital and orbital cellulitis are common but serious infections in children. Management of these infections varies because of an absence of clinical guidelines, but it is unclear if management within institutions has changed over time. We compared the management and outcomes of children hospitalized with periorbital and orbital cellulitis in 2 eras.

METHODS

Data were extracted from records of children hospitalized at a tertiary care children's hospital with periorbital or orbital cellulitis from 2000 to 2005 and 2012 to 2016. Patient demographics, cross-sectional imaging, antibiotic and corticosteroid use, length of stay, and surgical rates were collected. Data from the eras were compared by using descriptive statistics, t tests, Mann-Whitney U tests, Fisher's exact tests, and χ² tests.

RESULTS

There were 318 children included, 143 from 2000 to 2005 and 175 from 2012 to 2016. Compared with the first era, in the second era there were increased rates of MRI (5% vs 11%, P = .04), although rates of computed tomography scan use remained unchanged (60% vs 65%); increased number (1 vs 3, P < .01) and spectrum of antibiotics; increased use of intranasal corticosteroids (3% vs 49%, P < .01); and subspecialty consultation (89% vs 99%, P = .01). There were no differences in length of stay, readmission, or surgical rates between eras.

CONCLUSIONS

There has been considerable change in the management of hospitalized children with severe orbital infections at our institution, including the rates of MRI, number and spectrum of antibiotics used, use of adjunctive agents, and increased subspecialty involvement with no observed impact on clinical outcomes. Future research is needed to rationalize antimicrobial therapy and reduce low-value health care.

One cross-sectional investigation revealed that non-vaccine serotypes of Streptococcus pneumoniae could be identified more frequently in elderly Chinese people

OBJECTIVE

To analyze the serotype distribution and drug resistance of Streptococcus pneumoniae isolated from hospitalized patients of all ages in Zhongjiang county, Sichuan province, where the young children have just begun to vaccinate the PCV13 in private sector.

METHODS

Serotypes were determined for 387 isolates of S. pneumoniae by Quellung reaction. Antibiotic susceptibility was tested with the E-test or disc diffusion method.

RESULTS

The most common serotypes were type 19F and confirmed for 88 isolates (22.7%), followed by 19A (15.0%), 6B (7.8%), 16F (7.8%), 23F (7.0%) and 15A (4.4%). The coverage rates of PCV13 and PPSV23 were 63.3% and 65.1%. With the increase of age, the proportion of PCV13 types decreased significantly, from 71.3% (<2 years old) to 41.9% (≥60 years old). The intermediate rate and resistance rate of the isolates to oral penicillin were 48.6% and 45.2%, respectively. The resistance rate of erythromycin was high (94.4%). The PCV13 isolates was more resistant to penicillin than the non-PCV13 ones.

CONCLUSION

The PCV13 coverage rate in pediatric isolates was higher than those in adult isolates. The adults, especially the elderly, may be the reservoir of non-PCV13 types. It is necessary to investigate the serotype distribution of S. pneumoniae based on all age population to assess potential epidemics of non-vaccine serotype associated with PCVs administration.

Invasive Pneumococcal Disease in Adults in Portugal: The Importance of Serotypes 8 and 3 (2015-2018)

Increasing the uptake of the 13-valent pneumococcal conjugate vaccine (PCV13) in children is expected to alter the serotypes causing invasive pneumococcal disease (IPD) in adults due to herd protection. We characterized 2172 cases of adult IPD in 2015–2018 in Portugal after the introduction of PCV13 in the national immunization plan of 2015. Among the 58 detected serotypes, serotypes 8 (n = 413; 19%), 3 (n = 334; 15%), 22F (n = 148; 7%), 14 (n = 138; 6%), and 19A (n = 116; 5%) were the most frequent. Among PCV13 serotypes, 7F and 19A IPD decreased, but serotype 3 IPD remained stable. The non-PCV13 serotypes were a heterogeneous group, with serotypes 23A and 23B enriched among CSF cases; serotype 8 associated with younger patients; and serotypes 22F, 6C, and 31 associated with older patients. The continued increase of serotype 8 IPD was one of the drivers for the increased coverage of the 23-valent pneumococcal polysaccharide vaccine (PPV23; 80% in 2015–2018). Antimicrobial resistance was associated with older age and serotypes 6C, 11A, 14, 15A, 19A, and 19F. Three years after the introduction of PCV13 in the NIP with an uptake of >95%, the proportion of PCV13 serotypes causing IPD in adults stabilized in Portugal. The direct vaccination of adults may be important in preventing IPD in this age group.

Invasive pneumococcal disease in Canada 2010-2017: The role of current and next-generation higher-valent pneumococcal conjugate vaccines

BACKGROUND

In 2010-2011, the 13-valent pneumococcal conjugate vaccine (PCV13) replaced the 7- or 10-valent vaccine (PCV7 and PCV10, respectively) in pediatric immunization programs across Canada. For adults aged ≥65 years, the 23-valent pneumococcal polysaccharide vaccine (PPSV23) has been publicly funded for several decades; PCV13 funding was not recommended in this population, partly due to expected ongoing vaccine-serotype disease decline stemming from herd effects of the pediatric program. Higher-valent PCVs (ie, 15- and 20-valent PCVs [PCV15 and PCV20, respectively]) currently in development may become available in Canada in the coming years.

METHODS

Using the National Microbiology Laboratory surveillance reports, annual case counts and serotype distribution of invasive pneumococcal disease (IPD) from 2010 to 2017 in Canada were examined to assess the impact of existing programs on PCV13-serotype IPD and determine the proportion of IPD that can potentially be prevented by current and forthcoming higher-valent PCVs.

RESULTS

The percentages of PCV13-serotype IPD decreased from 55% [1492/2708] in 2010 to 30% [902/3006] in 2017 in all age groups combined, including a decline from 67% [221/331] to 18% [40/219] in children aged <5 years and from 50% [487/967] to 23% [287/1238] in adults aged ≥65 years. Overall, IPD cases declined mainly before 2014 and have plateaued since then. In 2017, PCV15- and PCV20-serotypes (inclusive of PCV13 serotypes) accounted for 42% and 58% of IPD cases, respectively, in all ages.

CONCLUSIONS

In Canada, publicly funded pediatric PCV13 use was associated with large declines in IPD due to vaccine serotypes. Substantial residual PCV13-serotype IPD proportions observed among all ages imply limits to indirect protection afforded by the pediatric PCV13 program at the current uptake level and suggest the adult PPSV23 program alone is insufficient. Higher-valent PCVs have the potential to address a substantial proportion of remaining IPD cases among all age groups.

Clinical characteristics and serotype distribution of invasive pneumococcal disease in pediatric patients from Beijing, China

Invasive pneumococcal disease (IPD) is associated with significant morbidity and mortality. However, limited studies have reported clinical features of IPD cases among Chinese children. This study aimed to evaluate clinical characteristics as well as serotype distribution of hospitalized IPD children in Beijing, China. Children with confirmed IPD were retrospectively recruited from January 2014 to December 2019. Clinical data were gathered from medical records, and serotypes of Streptococcus pneumoniae isolates were detected. Clinical differences between deaths and survivors were also compared, and risk factors associated with death were determined. Of sixty-eight children diagnosed with IPD, 58 (85.3%) were < 5 years. 19F was the predominant serotype (23, 33.8%), followed by 19A (14, 20.6%), 14 (12, 17.6%), 23F (5, 7.4%), and non-vaccine serotype (NVT) 15A (3, 4.4%). The coverage rate of 13-valent pneumococcal conjugate vaccine (PCV) was 92.6% (63). After introduction of PCV-13, there was a significant increase of IPD due to NVTs (p = 0.047). Sixteen (23.5%) children died, and diagnoses of 11 (68.8%) were meningitis. Risk factors for death were < 2 years (odds ratio [OR] [95% confidence interval {CI}]: 6.64 [1.14-32.10]; p = 0.019), altered mental status (OR [95%CI]: 10.10 [2.11-48.31]; p = 0.004), and septic shock (OR [95%CI]: 6.61 [1.11-39.50]; p = 0.038). This study revealed that the case fatality rate of hospitalized IPD children was high in this hospital. Fatal cases were more likely to be children < 2 years, presented with changed mental status and septic shock. Notably, we found that NVTs increased after PCV13 availability in China.

Invasive pneumococcal disease due to 22F and 33F in England: A tail of two serotypes

BACKGROUND

A 15-valent pneumococcal conjugate vaccine (PCV15) aims to protect against serotype 22F and 33F in addition to the serotypes within the 13-valent PCV (PCV13) which was introduced to the UK childhood immunisation programme in April 2010. Little is known about the specific epidemiology, clinical features or outcomes of invasive pneumococcal disease (IPD) due to these two serotypes.

METHODS

Public Health England (PHE) conducts enhanced IPD surveillance in England. Hospital laboratories routinely submit invasive pneumococcal isolates to PHE for serotyping and enhanced clinical information is collected through questionnaires sent to general practitioners. IPD due to serotypes 22F and 33F diagnosed during 2014/15-2018/19 were compared with IPD due to PCV13 serotypes and remaining serotypes.

RESULTS

In total, 25,415 isolates (93.4%) were serotyped and questionnaires were completed for 22,097 (86.9%) cases. Serotype 22F was responsible for 1,788 (7.0%) and serotype 33F for 893 (3.5%) cases compared to 19.9% (n = 5,047) for PCV13 and 69.6% (n = 17,687) for the remaining serotypes. IPD incidence increased for both serotypes since 2005/06, especially in older adults, but plateaued after PCV13 introduction. Comorbidity prevalence was 68.7% (n = 1,037) for serotype 22F and 67.2% (n = 505) for serotype 33F, with invasive pneumonia being the most common clinical presentation 1,067/1,482; 72.0%, and 514/755; 68.1%, respectively. There were 3,617 deaths within 30 days of disease onset, including 236 (CFR, 15.4%) among 22F, 128 (CFR, 16.5%) among 33F and 21.3% (925/4,350) among PCV13-type IPD cases. When compared with PCV13-type IPD, serotype 22F (aOR 0.58, 95%CI 0.49-0.68, p < 0.001) and 33F (aOR 0.73, 95%CI 0.59-0.91, p = 0.004) were independently associated with lower odds of death. The major circulating sequence types (STs) in 22F (ST 433, ST698) and 33F (ST717, ST100, ST673) were not associated with an increased risk of death compared to the other STs.

CONCLUSIONS

Serotype 22F and 33F-type IPD are associated with a lower risk of death compared to PCV13-type, with those presenting with septicaemia more likely to have a fatal outcome compared to pneumonia. PCV15 has the potential to prevent up to an additional 10% of IPD cases in England.

Immunogenicity following revaccination or sequential vaccination with 23-valent pneumococcal polysaccharide vaccine (PPSV23) in older adults and those at increased risk of pneumococcal disease: a review of the literature

Introduction: Immunogenicity studies evaluating sequential administration of pneumococcal conjugate vaccine (PCV) followed by 23-valent pneumococcal polysaccharide vaccine (PPSV23) or revaccination with PPSV23 have raised concerns that PPSV23 may not elicit higher antibody levels than those measured following PCV or first PPSV23 dose.Areas covered: Recent literature was evaluated for evidence of blunted immune response (hyporesponsiveness), focusing on studies using adequate intervals between doses in accordance with vaccination recommendations. In eight of nine studies that evaluated revaccination with PPSV23 at an interval of ≥5 years after the previous dose, immunoglobulin G geometric mean concentrations and/or opsonophagocytic assay geometric mean titers for most serotypes increased from pre- to post-repeat vaccination and were comparable between repeat and primary vaccination groups post-vaccination. In seven studies in which PPSV23 was administered after PCVs (8 weeks to 1 year apart), responses to PPSV23 were comparable to those seen after initial PCV dose for shared vaccine serotypes. Studies in which PCVs were administered after PPSV23 were not evaluated.Expert opinion: Published data suggest immune responses following repeat vaccination with PPSV23, or sequential PCV/PPSV23 vaccination, are robust, without evidence of hyporesponsiveness. PPSV23 vaccination of at-risk adults is essential to ensure broad protection against all 23 vaccine serotypes.

Efficacy and effectiveness of a 23-valent polysaccharide vaccine against invasive and noninvasive pneumococcal disease and related outcomes: a review of available evidence

Introduction: Routine pneumococcal vaccination for adults aged ≥60 or ≥65 years and those with underlying at-risk and high-risk conditions is recommended in many countries. However, studies estimating the effectiveness of 23-valent pneumococcal polysaccharide vaccine (PPSV23) have revealed mixed results, partly due to variability in study design and endpoints used to assess outcomes.Areas covered: The authors conducted a literature review of independently randomized trials and real-world studies published from 2010 to 2020 that assessed the effectiveness and efficacy of PPSV23 against vaccine-type or any-serotype invasive and noninvasive pneumococcal disease in adults aged ≥60 years. The authors also evaluated differences in study design that may contribute to the heterogeneity of available evidence.Expert opinion: Policy decisions regarding the inclusion of vaccines into national immunization plans should consider study quality and limitations. This review shows that PPSV23 is effective against vaccine-type invasive pneumococcal disease and vaccine-type pneumococcal pneumonia and can lower the burden of vaccine-type pneumococcal pneumonia. PPSV23-conferred protection may be lower in adults aged ≥75 years, those with certain underlying conditions, and individuals who were vaccinated >5 years before disease onset. This is an important finding that supports the benefit of PPSV23 vaccination for older adults.

Sugar-Coated Killer: Serotype 3 Pneumococcal Disease

Capsular polysaccharide (CPS), which surrounds the bacteria, is one of the most significant and multifaceted contributors to Streptococcus pneumoniae virulence. Capsule prevents entrapment in mucus during colonization, traps water to protect against desiccation, can serve as an energy reserve, and protects the bacterium against complement-mediated opsonization and immune cell phagocytosis. To date, 100 biochemically and serologically distinct capsule types have been identified for S. pneumoniae; 20 to 30 of which have well-defined propensity to cause opportunistic human infection. Among these, serotype 3 is perhaps the most problematic as serotype 3 infections are characterized as having severe clinical manifestations including empyema, bacteremia, cardiotoxicity, and meningitis; consequently, with a fatality rate of 30%-47%. Moreover, serotype 3 resists antibody-mediated clearance despite its inclusion in the current 13-valent conjugate vaccine formulation. This review covers the role of capsule in pneumococcal pathogenesis and the importance of serotype 3 on human disease. We discuss how serotype 3 capsule synthesis and presentation on the bacterial surface is distinct from other serotypes, the biochemical and physiological properties of this capsule type that facilitate its ability to cause disease, and why existing vaccines are unable to confer protection. We conclude with discussion of the clonal properties of serotype 3 and how these have changed since introduction of the 13-valent vaccine in 2000.

Comparison of PCV-10 and PCV-13 vaccine coverage for invasive pneumococcal isolates obtained across Canadian geographic regions, SAVE 2011 to 2017

To assess the coverage of invasive Streptococcus pneumoniae by pneumococcal conjugate vaccines (PCV)-10 and PCV-13 across Canada. In total, 9166 invasive S. pneumoniae isolates were collected as part of the SAVE 2011 to 2017 study. Serotyping was performed by the Quellung reaction and antimicrobial susceptibility testing was performed using CLSI methods. The proportion of both PCV-10 and PCV-13 serotypes decreased significantly (P < 0.0001) from 2011 (26.7% and 48.0%, respectively) to 2017 (11.2% and 26.2%). For central, western, and eastern regions of Canada, PCV-13 provided significantly greater (P < 0.0001) coverage at 33.7% (2060/6110), 23.0% (456/1985), and 36.3% (389/1071), respectively, compared to PCV-10 at 15.4% (939/6110), 10.1% (201/1985), and 15.8% (169/1071) coverage. PCV-13 provided significantly greater coverage (53.3%, 282/529) of multidrug-resistant (MDR) isolates (resistant to ≥3 antimicrobial classes) than PCV-10 (14.6%, 77/529, P < 0.0001). PCV-13 provided significantly greater coverage of invasive S. pneumoniae serotypes, as well as coverage of MDR isolates, than PCV-10.

Therapeutic Activity of Type 3 Streptococcus pneumoniae Capsule Degrading Enzyme Pn3Pase

PURPOSE

Streptococcus pneumoniae (Spn) serotype 3 (Spn3) is considered one of the most virulent serotypes with resistance to conventional vaccine and treatment regimens. Pn3Pase is a glycoside hydrolase that we have previously shown to be highly effective in degrading the capsular polysaccharide of type 3 Spn, sensitizing it to host immune clearance. To begin assessing the value and safety of this enzyme for future clinical studies, we investigated the effects of high doses of Pn3Pase on host cells and immune system.

METHODS

We assessed the enzyme's catalytic activity following administration in mice, and performed septic infection models to determine if prior administration of the enzyme inhibited repeat treatments of Spn3-challenged mice. We assessed immune populations in mouse tissues following administration of the enzyme, and tested Pn3Pase toxicity on other mammalian cell types in vitro.

RESULTS

Repeated administration of the enzyme in vivo does not prevent efficacy of the enzyme in promoting bacterial clearance following bacterial challenge, with insignificant antibody response generated against the enzyme. Immune homeostasis is maintained following high-dose treatment with Pn3Pase, and no cytotoxic effects were observed against mammalian cells.

CONCLUSIONS

These data indicate that Pn3Pase has potential as a therapy against Spn3. Further development as a drug product could overcome a great hurdle of pneumococcal infections.

Incidence of invasive pneumococcal disease after introduction of the 13-valent conjugate pneumococcal vaccine in British Columbia: A retrospective cohort study

BACKGROUND

A significant reduction in invasive pneumococcal disease (IPD) has been reported, across all ages, following the implementation of 7-valent conjugate pneumococcal vaccine (PCV7) globally, as part of infant immunization programs. We explored the additional impact of PCV13 on IPD over a 14-year period.

METHODS

Using provincial laboratory surveillance and hospitalization data (N = 5791), we calculated the annual incidence of IPD following the implementation of PCV13 vaccine. Poisson regression was used to evaluate changes in the overall incidence of IPD, and serotype-specific IPD between PCV7 (2004-10) and PCV13 (2011-2015) eras.

RESULTS

Overall, IPD rates have seen a modest decline in the PCV13 compared to the PCV7 era (IRR 0.84; 95% CI: 0.79-0.89); this was seen in children ≤2 years of age, and the majority of the adult cohort. Rates of vaccine-type IPD (PCV7 and PCV13) also decreased in the PCV13 era. In contrast, IPD incidence related to non-PCV13 (IRR: 1.56; 95%CI:1.43-1.72) and non-vaccine serotypes (IRR: 2.12; 95%CI:1.84-2.45) increased in the PCV13 era compared to the PCV7 era.

CONCLUSIONS

A modest reduction in IPD from the PCV13 vaccine was observed, with gains limited to the immunized cohort and adults. However, a significant increase in non-vaccine serotypes emphasizes the need for continued surveillance.

Molecular epidemiological characterization in mucoid-type Streptococcus pneumoniae isolates obtained from invasive pneumococcal disease patients in Japan

INTRODUCTION

Streptococcus pneumoniae with a mucoid-type capsule is associated with invasive pneumococcal diseases (IPDs). Despite the introduction of pneumococcal vaccines, IPDs caused by mucoid-type isolates are still prevalent. The present study aimed to characterize mucoid-type S. pneumoniae isolated from IPD patients throughout Japan in 2017 (post-vaccination era).

METHODS

A total of 225 mucoid-type isolates were collected. The serotype, antimicrobial susceptibility, and multilocus sequence type of these isolates were determined.

RESULTS

The prevalence of IPDs caused by mucoid-type isolates was high in adults, especially in the elderly (≥65 years of age), and prognosis in these patients was significantly poor. Of the mucoid-type isolates, the predominant serotype was serotype 3 (84.4%), and the remaining were serotypes 37 (15.1%) and 8 (0.4%). Antimicrobial susceptibility showed that most mucoid isolates exhibited the penicillin-intermediate resistant S. pneumoniae genotype (gPISP). However, the serotype 3 isolate exhibited the penicillin-resistant S. pneumoniae genotype (gPRSP). This gPRSP isolate was classified into ST166, which is related to serotypes 9 V and 11 strains. Sequence analysis of the capsule-coding regions and its flanking regions indicated that recombination occurred upstream and downstream of the capsule-coding region, suggesting that gPRSP (serotype 9 V/ST166) obtaining the type-3 capsule gene cluster resulted in the emergence of gPRSP (serotype 3/ST166).

CONCLUSIONS

Our findings indicated that IPDs caused by mucoid-type S. pneumoniae are still a serious concern and mucoid-type S. pneumoniae with novel phenotype could emerge via capsular switching in response to environmental changes such as introduction of vaccines and improper use of antimicrobial agents.

The potential role of pneumococcal conjugate vaccine in reducing acute respiratory inflammation in community-acquired pneumococcal pneumonia

Background

Pneumococcal conjugate vaccine (PCV) reduces both invasive pneumococcal disease (IPD) and other pneumococcal infections worldwide. We investigated the impact of stepwise implementation of childhood PCV programs on the prevalence of pneumococcal pneumonia, severity of acute inflammation, and associations between breakthrough pneumonia and pneumococcal serotypes in Taiwan.

Methods

In total, 983 children diagnosed with community-acquired pneumococcal pneumonia were enrolled between January 2010 and December 2015.

Results

Proportions of pneumococcal vaccinations increased each year in age-stratified groups with PCV7 (32.2%) as the majority, followed by PCV13 (12.2%). The proportion of pneumococcal pneumonia decreased each year in age-stratified groups, especially in 2–5 year group. Serotype 19A is the leading serotype either in vaccinated (6.4%) or unvaccinated patients (5.2%). In particular, vaccinated patients had significantly higher lowest WBC, lower neutrophils, lower lymphocytes and lower CRP values than non-vaccinated patients (p < 0.05). After stratifying patients by breakthrough infection, those with breakthrough pneumococcal infection with vaccine coverage serotypes had more severe pneumonia disease (p < 0.05).

Conclusion

Systematic childhood pneumococcal vaccination reduced the prevalence of community-acquired pneumococcal pneumonia, especially in 2–5 year group. Serotype 19A was the major serotype for all vaccine types in patients with pneumococcal pneumonia and severity of acute inflammatory response was reduced in vaccinated patients.

Recent advances in the epidemiology and prevention of Streptococcus pneumoniae infections

The introduction of pneumococcal conjugate vaccines (PCVs) 7 and 13 into national childhood immunization programs in the US in 2000 and 2010, respectively, proved to be remarkably successful in reducing infant mortality due to invasive pneumococcal disease (IPD), resulting in widespread uptake of these vaccines. Secondary herd protection of non-vaccinated adults against IPD has proven to be an additional public health benefit of childhood immunization with PCVs, particularly in the case of the vulnerable elderly who are at increased risk due to immunosenescence and underlying comorbidity. Despite these advances in pneumococcal immunization, the global burden of pneumococcal disease, albeit of unequal geographic distribution, remains high. Reasons for this include restricted access of children living in many developing countries to PCVs, the emergence of infection due to non-vaccine serotypes of the pneumococcus, and non-encapsulated strains of the pathogen. Emerging concerns affecting the elderly include the realization that herd protection conferred by the current generation of PCVs (PCV7, PCV10, and PCV13) has reached a ceiling in many countries at a time of global population aging, compounded by uncertainty surrounding those immunization strategies that induce optimum immunogenicity and protection against IPD in the elderly. All of the aforementioned issues, together with a consideration of pipeline and pending strategies to improve access to, and serotype coverage of, PCVs, are the focus areas of this review.