Pneumococcal Conjugate Vaccine Research Articles

A genome-based survey of invasive pneumococci in Norway over four decades reveals lineage-specific responses to vaccination

BackgroundStreptococcus pneumoniae is a major cause of mortality globally. The introduction of pneumococcal conjugate vaccines (PCVs) has reduced the incidence of the targeted serotypes significantly, but expansion of non-targeted serotypes, serotype replacement, and incomplete vaccine-targeting contribute to pneumococcal disease in the vaccine era. Here, we characterize the changing population genetic landscape of S. pneumoniae in Norway over a 41-year period (1982–2022).MethodsSince 2018, all cases of invasive pneumococcal disease have undergone whole-genome sequencing (WGS) at the Norwegian Institute of Public Health. In order to characterize the changing population over time, historical isolates were re-cultured and sequenced, resulting in a historical WGS dataset. Isolates were assigned to global pneumococcal sequence clusters (GPSCs) using PathogenWatch and assigned to serotypes using in silico (SeroBA) and in vitro methods (Quellung reaction). Temporal phylogenetic analyses were performed on GPSCs of particular interest.ResultsThe availability of WGS data allowed us to study capsular variation at the level of individual lineages. We detect highly divergent fates for different GPSCs following the introduction of PCVs. For two out of eight major GPSCs, we identified multiple instances of serotype switching from vaccine types to non-vaccine types. Dating analyses suggest that most instances of serotype switching predated the introduction of PCVs, but expansion occurred after their introduction. Furthermore, selection for penicillin non-susceptibility was not a driving force for the changing serotype distribution within the GPSCs over time.ConclusionsPCVs have been major shapers of the Norwegian disease-causing pneumococcal population, both at the level of serotype distributions and the underlying lineage dynamics. Overall, the introduction of PCVs has reduced the incidence of invasive disease. However, some GPSCs initially dominated by vaccine types escaped the effect of vaccination through expansion of non-vaccine serotypes. Close monitoring of circulating lineages and serotypes will be key for ensuring optimal vaccination coverage going forward.

The Microbiology of Acute Mastoiditis Infections Presenting to a large UK Tertiary Paediatric ENT centre in a post Pneumococcal Conjugate Vaccination era.

The Microbiology of Acute Mastoiditis Infections Presenting to a large UK Tertiary Paediatric ENT centre in a post Pneumococcal Conjugate Vaccination era.

Effect of 10-valent pneumococcal conjugate vaccine on trends of pneumococcal meningitis in children under five years, Uganda, 2003-2022.

Pneumococcal meningitis, a vaccine-preventable disease caused by Streptococcus pneumoniae (Spn) is the leading bacterial meningitis in under five children. In April 2014, Uganda introduced routine immunization with 10-valent Pneumococcal Conjugate Vaccine (PCV10) for infants. The target coverage for herd immunity is ≥ 90% with three doses (PCV10-dose 3). We assessed the effect of PCV10 introduction and coverage on the trends of pneumococcal meningitis in under five children. We analyzed laboratory-confirmed pediatric bacterial meningitis (PBM) data at two high-volume WHO-accredited sentinel surveillance hospitals in Kampala City and Gulu District, from 2003 to 2022. We used confirmed cases to estimate the minimum incidence of pneumococcal meningitis in the host districts and calculated annual incidence of pneumococcal meningitis per one million populations, and the proportion of confirmed PBM attributable to Spn. We divided the study period into 2003-2013 (pre-PCV10) and 2014-2022 (post-PCV10), and conducted interrupted time series analysis using autoregressive integrated moving average models for the effect of PCV10 on trends of pneumococcal meningitis and PBM attributable to Spn. We analyzed reported PCV10 data in DHIS2 from 2014 to 2022 for annual PCV10-dose 3 coverage. Among the 534 confirmed PBM cases, 331(62%) were pneumococcal meningitis; 227(69%) from Gulu District and 104(31%) from Kampala City. The majority (95%) of the isolates were not serotyped. The majority (57%) were male and unimmunized (98%); median age = 14(IQR = 6-27) months with most (55%) aged ≥ 12 months. The case-fatality rate was 9%. During Pre-PCV10 period, the overall incidence of pneumococcal meningitis in the host districts increased; slope change = 1.0 (95%CI = 0.99999, 1.00001) but declined in post-PCV10 period (2014-2022) by 92% from 86 cases /1,000,000 in 2014 to 7/1,000,000 in 2022, slope change= -1.00006 (95%CI=-1.00033, -0.99979). Whereas there was an immediate decline in the proportion of confirmed PBM attributable to Spn in the host districts, level change=-1.84611(95%CI=-1.98365,-1.70856), an upward trend was recorded from 2016 to 2022, slope change = 1.0 (95%CI = 0.99997, 1.00003). During 2015-2022, PCV10-dose 3 coverage was largely > 90% for Gulu District and 52-72% for Kampala City. The PCV10 routine immunization program reduced the incidence of pneumococcal meningitis in Kampala City and Gulu District. There was no effect on the confirmed PBM proportionately attributable to Spn. Kampala City persistently recorded PCV10-dose3 coverage < 90%. We recommend enhancing serotyping and periodic nasopharyngeal carriage surveys to ascertain the maximum vaccine effectiveness and monitor Spn serotypes, and strengthening routine immunization in Kampala City.

Burden of Pneumococcal Disease in Young Children Due to Serotypes Contained in Different Pneumococcal Conjugate Vaccines in Eight Asian Countries and Territories.

Pneumococcal disease (PD) is a major cause of morbidity and mortality in young children in Asia and globally. Pneumococcal conjugate vaccines (PCVs) have significantly reduced the burden of PD when included in pediatric national immunization programs (NIPs). This study estimates the clinical and economic burden of PD due to serotypes contained in different PCVs in children aged < 5 years in eight Asian countries/territories. Based on published data, a cohort-based decision analytic model was used to estimate annual PD cases, deaths, and direct medical costs associated with serotypes contained in PCV10, PCV13, PCV15, and PCV20. PD incidence rates were lower in regions with PCV13 in their NIP than those without. Serotypes contained in higher but not lower valency PCVs resulted in a significant incremental clinical and economic burden, although the difference between PCV13 and PCV15 serotypes was generally small. Moving from PCV13 to PCV20 was estimated to result in greater clinical and economic burden reductions. This study demonstrates the remaining and incremental burden of PD from PCV10 to PCV20 serotypes in young children in selected Asian regions. Extending NIP access to higher-valency PCVs with broader serotype coverage and improving vaccine uptake will help prevent morbidity and deaths and save healthcare costs.

Epidemiology of pneumococcal meningitis in sentinel hospital surveillance of Viet Nam, 2015–2018

BackgroundStreptococcus pneumoniae (S. pneumoniae), Haemophilus influenzae (H. influenzae), and Neisseria meningitidis (N. meningitidis) are leading causes of childhood bacterial meningitis and preventable by vaccines. The aim of this hospital-based sentinel surveillance is to describe the epidemiological characteristics of pneumococcal meningitis, including disease burden, and to provide baseline data on pneumococcal serotype distribution to support decision making for pneumococcal conjugate vaccine (PCV) introduction in Vietnam.MethodsSurveillance for probable bacterial meningitis in children 1–59 months of age is conducted in three tertiary level pediatric hospitals: one in Hanoi and two in Ho Chi Minh City. Cerebrospinal fluid (CSF) specimens were collected via lumbar puncture from children with suspected meningitis. Specimens were transferred immediately to the laboratory department of the respective hospital for cytology, biochemistry, and microbiology testing, including culture. PCR testing was conducted on CSF specimens for bacterial detection (S. pneumoniae, H. influenzae, and N. meningitidis) and pneumococcal serotyping.ResultsDuring 2015–2018, a total of 1,803 children with probable bacterial meningitis were detected; 1,780 had CSF specimens available for testing. Of 245 laboratory-confirmed positive cases, the majority were caused by S. pneumoniae (229,93.5%). Of those with S. pneumoniae detected, over 70% were caused by serotypes included in currently available PCV products; serotypes 6 A/6B (27.1%), 14 (19.7%), and 23 F (16.2%) were the most common serotypes. Children with laboratory-confirmed pneumococcal meningitis were more likely to live in Hanoi (p < 0.0001) and children 12–23 months of age were at greater odds (OR = 1.65, 95% CI: 1.11, 2.43; p = 0.006) of having confirmed pneumococcal meningitis compared to children < 12 months of age when compared to those without laboratory-confirmed bacterial meningitis. Additionally, children with confirmed pneumococcal meningitis were more likely to exhibit signs and symptoms consistent with clinical meningitis compared to negative laboratory-confirmed meningitis cases (p < 0.0001) and had a greater odds of death (OR = 6.18, 95% CI: 2.98, 12.86; p < 0.0001).ConclusionsPneumococcal meningitis contributes to a large burden of bacterial meningitis in Vietnamese children. A large proportion are caused by serotypes covered by PCVs currently available. Introduction of PCV into the routine immunization program could reduce the burden of pneumococcal meningitis in Viet Nam.

Clinical and economic burden of otitis media in children under 5 years of age in the United States: A retrospective study

ABSTRACT Reductions in all-cause otitis media (OM) following widespread pneumococcal conjugate vaccine use have plateaued. Granular burden of disease data are needed to guide evaluation and implementation of new measures targeting OM prevention. We conducted a retrospective study to assess the incidence and treatment costs of OM, tympanostomy tube placement (TTP), and hearing loss in children aged <5 years in the United States (US). OM episodes and TTP between 2016 and 2017 were identified in IBM MarketScan Commercial Claims and Encounters, Medicare Supplemental and Coordination of Benefits, and Multi-Medicaid databases using diagnosis codes (ICD-10). The incidence rate per 100,000 person-years (IR) of OM in <5-year-olds was 62,726 in Commercial/Medicare databases and 55,874 in Medicaid. IRs peaked at 9–<12 months (115,552 and 110,960, respectively). Approximately 5% and 4% of OM episodes in the respective databases had TTP (IR 3233 and 2404). Around 2% of children with OM had hearing loss (IR 1468 and 1109, respectively), of whom 41% had TTP. We estimated that there were 11.1 million OM episodes in 2020 costing USD 4.8 billion. 243,618 children were estimated to have OM with hearing loss at a direct total cost of USD 637 million, or 13% of the overall cost. The clinical and economic burden attributable to OM in the US was high in children aged <5 years during the study period. Novel approaches are needed to improve and broaden vaccine-induced protection against OM and its complications. The study results could guide policymakers considering age-specific interventions to reduce the OM burden.

Impact of PCV13 and PPSV23 Vaccination on Invasive Pneumococcal Disease in Adults with Treated Rheumatoid Arthritis: A Population-Based Study

On-time receipt of pneumococcal vaccines is essential in patients with rheumatoid arthritis (RA) as immunosuppressive medications increase their risk of invasive pneumococcal disease (IPD). However, data regarding the impact of timely administration of these vaccines on the risk of developing IPD are lacking for RA patients. We conducted a retrospective cohort study to assess the impact of on-time vaccination for pneumococcal conjugate vaccine (PCV) 13 and pneumococcal polysaccharide vaccine (PPSV) 23 in patients treated for RA on the development of IPD using national Veterans Affairs data from 2010 to 2018. Patients &gt; 18 years of age, diagnosed with RA, and newly initiated on RA treatment were included. Pneumococcal vaccine compliance was assessed by measuring on-time receipt of PCV13 and PPSV23 vaccinations. A total of 33,545 patients were included in the cohort. Non-compliance with PCV recommendations was associated with an increased risk of IPD in a multivariable logistic regression model. This finding was consistent whether IPD status was ascertained by International Classification of Diseases coding (OR 2.42, 95%CI 2.14–2.73) or microbiologic data (OR 1.64, 95%CI 1.26–2.14). Providers should actively seek opportunities to provide pneumococcal vaccinations to patients with RA, as their on-time administration is associated with a decreased risk of IPD.

Prediction of post-PCV13 pneumococcal evolution using invasive disease data enhanced by inverse-invasiveness weighting.

After introducing pneumococcal conjugate vaccines (PCVs), serotype replacement occurred in Streptococcus pneumoniae. Predicting which pneumococcal strains will become common in carriage after vaccination can enhance vaccine design, public health interventions, and understanding of pneumococcal evolution. Invasive pneumococcal isolates were collected during 1998-2018 by the Active Bacterial Core surveillance (ABCs). Carriage data from Massachusetts (MA) and Southwest United States were used to calculate weights. Using pre-vaccine data, serotype-specific inverse-invasiveness weights were defined as the ratio of the proportion of the serotype in carriage to the proportion in invasive data. Genomic data were processed under bioinformatic pipelines to define genetically similar sequence clusters (i.e., strains), and accessory genes (COGs) present in 5-95% of isolates. Weights were applied to adjust observed strain proportions and COG frequencies. The negative frequency-dependent selection (NFDS) model predicted strain proportions by calculating the post-vaccine strain composition in the weighted invasive disease population that would best match pre-vaccine COG frequencies. Inverse-invasiveness weighting increased the correlation of COG frequencies between invasive and carriage data in linear or logit scale for pre-vaccine, post-PCV7, and post-PCV13; and between different epochs in the invasive data. Weighting the invasive data significantly improved the NFDS model's accuracy in predicting strain proportions in the carriage population in the post-PCV13 epoch, with the adjusted R2 increasing from 0.254 before weighting to 0.545 after weighting. The weighting system adjusted invasive disease data to better represent the pneumococcal carriage population, allowing the NFDS mechanism to predict strain proportions in carriage in the post-PCV13 epoch. Our methods enrich the value of genomic sequences from invasive disease surveillance.IMPORTANCEStreptococcus pneumoniae, a common colonizer in the human nasopharynx, can cause invasive diseases including pneumonia, bacteremia, and meningitis mostly in children under 5 years or older adults. The PCV7 was introduced in 2000 in the United States within the pediatric population to prevent disease and reduce deaths, followed by PCV13 in 2010, PCV15 in 2022, and PCV20 in 2023. After the removal of vaccine serotypes, the prevalence of carriage remained stable as the vacated pediatric ecological niche was filled with certain non-vaccine serotypes. Predicting which pneumococcal clones, and which serotypes, will be most successful in colonization after vaccination can enhance vaccine design and public health interventions, while also improving our understanding of pneumococcal evolution. While carriage data, which are collected from the pneumococcal population that is competing to colonize and transmit, are most directly relevant to evolutionary studies, invasive disease data are often more plentiful. Previously, evolutionary models based on negative frequency-dependent selection (NFDS) on the accessory genome were shown to predict which non-vaccine strains and serotypes were most successful in colonization following the introduction of PCV7. Here, we show that an inverse-invasiveness weighting system applied to invasive disease surveillance data allows the NFDS model to predict strain proportions in the projected carriage population in the post-PCV13/pre-PCV15 and pre-PCV20 epoch. The significance of our research lies in using a sample of invasive disease surveillance data to extend the use of NFDS as an evolutionary mechanism to predict post-PCV13 population dynamics. This has shown that we can correct for biased sampling that arises from differences in virulence and can enrich the value of genomic data from disease surveillance and advance our understanding of how NFDS impacts carriage population dynamics after both PCV7 and PCV13 vaccination.

Case Report: Emergence of de novo Donor-Specific HLA antibodies post Pneumococcal &amp; Varicella Zoster Vaccinations in Waitlisted Renal Transplant Candidate

Abstract Introduction/Objective In renal transplant waitlisted patients, vaccination series remains to be the standard of care for infection prevention. There is a need to investigate if any of these vaccines or their adjuvant components can induce de novo donor-specific antibodies (dnDSA) against human leukocyte antigens (HLA). These novel anti-HLA antibodies in renal transplant waitlisted patients can result in a positive flow cell crossmatch (FCXM) associated with an increased risk of renal transplant rejection. Methods/Case Report We present a 59-year-old renal transplant waitlisted patient who has had multiple negative T- cell and B-cell FCXM with no detection of dnDSA at baseline. We detected de-novo anti-HLA antibodies after he received pneumococcal conjugate (Pneum-C-13) and recombinant zoster vaccine (RZV). After vaccination, FCXM was positive for both T-cells and B-cells. HLA class I antibodies (A1, 23, 24, 80; B44, 45, 76) showed a panel reactive antibody (PRA) of 51%. Epitope analysis highlighted 166DG and 166ES as shared epitopes responsible for the entire specificity. The A1 dn-DSA had a mean fluorescence intensity (MFI) of 1800 and with shared A80 epitope MFI was 15,000 contributing to the strong positivity observed in T-cell and B-cell FCXM. New onset A1, and B44 DSA predicted high risk for transplant rejection with his sibling. His planned live donor renal transplant was halted and had to instead enter the kidney-paired donor program wherein he received his transplantation after 16 months. Results (if a Case Study enter NA) NA Conclusion Allosensitization risk secondary to RZV or Pneum-C-13 vaccines or their adjuvant components in renal transplant waitlisted patients must be considered as a potential risk for transplant rejection. Future studies can utilize monitoring of HLA-specific memory B-cells to provide crucial insights into the primary mechanism of action of dn-DSA anti-HLA antibody formation and suggest interventions to mitigate this memory B-cell activation.

Contact with young children is a major risk factor for pneumococcal colonization in older adults

Abstract Background Important questions remain about the sources of transmission of pneumococcus to older adults in the community. This is critical for understanding the potential effects of using pneumococcal conjugate vaccines (PCVs) in children and older adults. For non-institutionalized individuals, we hypothesized that the most likely source of adult-to-adult transmission is within the household. Methods We designed a longitudinal study to sample adults ≥60 years of age living in the same household (New Haven, CT, USA), without younger residents in the household. Saliva samples and social and health questionnaires were obtained every 2 weeks for a period of 10 weeks. DNA extracted from culture-enriched saliva was tested using qPCR for pneumococcus genes piaB, lytA, and serotype. Results Across two study seasons (November 2020-August 2021, November 2021-September 2022), 121 individuals from 61 households completed all 6 visits; 62 individuals were enrolled in both seasons. Overall, 52/1088 (4.8%) samples tested positive for pneumococcus, with 27/121 (22.3%) individuals colonized at least once. Several individuals were colonized at multiple timepoints; two individuals were colonized at 5/6 time points and two at all six. In 5 instances, both household members were carriers in the same season, though not necessarily at the same time. Pneumococcal carriage was substantially higher among individuals who had contact with children (10.0% vs 1.6%). Conclusions Contact with young children was the most important factor that influenced pneumococcal acquisition rates. While there were several instances where both adult household members were colonized at the same time or at sequential visits, these individuals typically had contact with children. As such, PCV immunization can directly protect older adults who have contact with children.

Immunization with recombinant Streptococcus pneumoniae PgdA protects mice against lung invasion.

Current pneumococcal vaccines, including the pneumococcal polysaccharide (PPV23) and conjugate (PCV13) vaccines, offer protection against specific serotypes but pose risks of serotype replacement that can alter the composition of the nasopharyngeal microbiota. To address this challenge, a novel strategy has been proposed to provide effective protection without disrupting the colonization of other bacterial populations. In our study, we found that subcutaneous immunization with recombinant peptidoglycan N-acetylglucosamine deacetylase A (rPgdA) elicited robust humoral and cellular immune responses, significantly reducing the invasion of Streptococcus pneumoniae in the lungs without affecting nasopharyngeal carriage. Furthermore, rPgdA antisera were shown to diminish bacterial invasion of lung epithelial cells in vitro. Notably, sera from patients with invasive pneumococcal infections exhibited higher levels of antibodies against the PgdA protein compared to sera from healthy adults, suggesting that a natural immune response to this protein occurs during infection. These results suggest a promising new target for the development of pneumococcal vaccines.

Capvaxive - A 21-valent pneumococcal conjugate vaccine.

The FDA has licensed Capvaxive (PCV21; Merck), a 21-valent pneumococcal conjugate vaccine, for prevention of invasive pneumococcal disease (IPD) and pneumococcal pneumonia in adults. Four other pneumococcal vaccines are currently available in the US: Prevnar 20 (PCV20), Vaxneuvance (PCV15), and Prevnar 13 (PCV13) are conjugate vaccines licensed for use in persons ≥6 weeks old, and Pneumovax 23 (PPSV23) is a pneumococcal polysaccharide vaccine licensed for use in persons ≥2 years old.

A Systematic Review and Meta-Analysis of the Efficacy of Antimicrobial Chemoprophylaxis for Recurrent Acute Otitis Media in Children.

Acute otitis media (AOM) is a common childhood infection. Recurrent AOM affects a subset of children, resulting in an adverse impact on quality of life, socioeconomic disadvantage, and risk of long-term sequelae. Antimicrobial chemoprophylaxis is used in some settings but is increasingly controversial due to an awareness of adverse long-term effects and contribution to global antibiotic resistance. A comprehensive literature search was undertaken using Medline (1946-October 2023) and Embase (1974-October 2023). The primary aim was to assess the efficacy of antimicrobial chemoprophylaxis on AOM episodes in children < 18 years of age. Bias and quality assessment was performed. Dichotomous data were analysed using risk ratio with 95% confidence intervals. Meta-analysis was carried out using random-effects models for pooled analysis, independent of heterogeneity. Heterogeneity was assessed using the I2 statistic. The effect of antimicrobial chemoprophylaxis in children with rAOM on the number of individual AOM episodes. assessment of antimicrobial agents and outcomes in children with risk factors. Assessment of qualitative data was performed on 20 studies (n = 2210). No controlled trials were identified post-multivalent pneumococcal conjugate vaccine (PCV) introduction, restricting current generalisability. Quantitative meta-analysis on nine pre-PCV studies (n = 1087) demonstrated antimicrobial chemoprophylaxis reduced any episode of AOM with a risk ratio 0.59 (95% CI 0.45-0.77). Families and clinicians must balance marginal short-medium term benefit (based on pre-PCV data), and the potential for adverse effects to that individual, and the societal risk of antimicrobial resistance with prolonged antibiotic use.

Pneumococcal Serotype-Specific Antibodies in Children with Recurrent Oto-sinopulmonary Infections.

Low titers to pneumococcal vaccine are a frequent finding in pediatric patients with recurrent oto-sinopulmonary infections. To characterize the pre- and post-immunization antibody trend for each serotype included in the pneumococcal 13-valent conjugate vaccine (PCV13), in a cohort of pediatric patients with recurrent oto-sinopulmonary infections. This retrospective review identified 182 patients with recurrent oto-sinopulmonary infections (131 required an immune workup and 99 had low pneumococcal titers leading to a PCV13 vaccine booster). Baseline pneumococcal serotype-specific antibody titers at initial visit and 6 weeks after the vaccine booster were obtained. An adequate response to the pneumococcal conjugate vaccine was deemed to be a 4-fold increase over baseline and/or a post-immunization titer of 1.3 µg/ml or greater. Overall, PCV13 booster provided a significant improvement in the number of protective titers, increasing from 3.6 serotypes at baseline to 11.1 serotypes at 6 weeks (p < 0.001). This increase correlated with improved clinical outcomes (81% showed no signs of recurrent infection after the first booster and 94% after a second booster). Post-immunization antibody concentrations were significantly higher than at baseline for all serotypes (p< 0.05) and only 8, 9N, and 12F did not exhibit a greater than 4-fold increase (p> 0.05) 6 weeks following booster. There were no differences between patients at different ages in post-immunization titer levels for all serotypes. In pediatric patients with recurrent oto-sinopulmonary infections, an additional pneumococcal booster proved to be effective in the protection of these children against further infections, across all age groups.

How effective is 13-valent pneumococcal conjugate vaccine (PCV13) combined with 23-valent pneumococcal polysaccharide vaccine (PPSV23)?

The bacterium Streptococcus pneumoniae remains a major causeof morbidity and mortality worldwide. Currently, the 2 leading vaccines targeted against it are: 23-valent pneumococcal polysaccharide vaccine (PPSV23) and 13-valent pneumococcal conjugate vaccine (PCV13). It was only very recently, starting 22 November 2019, that the Advisory Committee on Immunisation Practices (ACIP) no longer recommends routine administration of PCV13 for all adults aged 65 and above. As such, this systematic review aims to investigate how the use of PCV13 combined with PPSV23 compares to using PPSV23 alone in older adults. Relevant research papers were chosen through an electronic searchin PubMed. A set of selection criteria was then applied to ensure that the papers aligned with the objectives of this paper. The majority of the studies included in this paper demonstrated that in adults aged 50 years and above, PCV13 had the ability to generate a strong immune response in adults, even more so than PPSV23 for all of the twelve serotypes common to both vaccines. The safety of PCV13 was also demonstrated in the studies as no PCV13-related serious adverse events (SAEs) had surfaced. Only one study included in this systematic review opposed the trend.While the evidence for both PCV13’s and PPSV23’s ability to generate an immune response have been persuasive, more research that focuses on the clinical endpoint in older adults, as well as the incidence of pneumococcal infections in the population, could be done to fully address the main question of this paper.

Radiographically confirmed pneumonia in Malawian children and associated pneumococcal carriage after introduction of the 13-valent pneumococcal conjugate vaccine

BackgroundThe 13-valent pneumococcal conjugate vaccine (PCV-13) was introduced in Malawi in 2011 with an expected impact of reducing pneumococcal pneumonia in children. We aimed to describe clinical characteristics and nasopharyngeal (NP) carriage of pneumococcus by serotype in children hospitalized with primary end-point pneumonia (PEP) between 2013 and 19 after the introduction of PCV-13.MethodsWe conducted a secondary analysis of children aged under-5-years hospitalized with acute respiratory illness (ARI) in Malawi. Chest radiographs conducted at admission were read by two independent clinicians according to WHO criteria for PEP, and a third reviewer resolved discordant diagnoses. NP swab specimens were processed and Streptococcus pneumoniae growth was serotyped. Multivariable regression analysis was conducted to assess the association between clinical characteristics, NP serotypes, and PEP.ResultsWe had complete radiographic and NP serotype data for 500 children, of which 54 isolates were vaccine-type (VT) (10.8%), 165 were non-VT (NVT; 33.0%), and 281 had no pneumococcal growth (56.2%). Among these, 176 (35.2%) had PEP on chest x-ray. Among those with PEP, pneumococcal carriage was documented in 43.8% of cases, and VT serotypes accounted for 10.8%. For children with PEP, we found no association between clinical characteristics and carrying either VT, NVT, or no pneumococcus.ConclusionCarriage of S. pneumoniae remains high among children hospitalized with ARI in Malawi, but children with VT carriage were no more likely to have PEP than children carrying no pneumococcus or those with NVT carriage. There were no differences in clinical characteristics between those carrying VT, NVT, or no pneumococcus.

Safety of a 4-Dose 20-Valent Pneumococcal Conjugate Vaccine Series in Infants: A Randomized Trial.

The 20-valent pneumococcal conjugate vaccine (PCV20) was developed to expand protection for pneumococcal disease. It contains all 13-valent pneumococcal conjugate vaccine (PCV13) components plus conjugates for 7 additional serotypes. Our primary objective with this study was to evaluate PCV20 tolerability and safety. In this phase 3, multi-country, double-blind study, healthy infants born at ≥34 weeks' gestation were randomly assigned 2:1 to receive PCV20 or PCV13 at 2, 4, 6, and 12 to 15 months of age. Safety assessments included local reactions and systemic events within 7 days after each vaccination, adverse events (AEs) from dose 1 to 1 month after dose 3 and from dose 4 to 1 month after dose 4, and serious AEs and newly diagnosed chronic medical conditions from dose 1 through 6 months after the last dose. Participants received PCV20 (N = 1000) or PCV13 (N = 504); 91.7% received all 4 doses. The frequencies of local reactions and systemic events were generally similar in PCV20 and PCV13 groups, with most reported as mild or moderate. The most common local reaction was injection site pain (PCV20, 24.7% to 40.5%; PCV13, 26.8% to 42.0%); irritability was the most common systemic event (PCV20, 54.8% to 68.2%; PCV13, 54.7% to 68.5%). AE frequencies were similar in both groups. No serious AEs were related to study vaccines. Few newly diagnosed chronic medical conditions were reported (2.8% in both groups). PCV20 was safe across multiple countries, in late preterm infants, and when administered with other vaccines. A 4-dose series of PCV20 had a tolerability and safety profile similar to that of PCV13.

Effect of O-acetylation on the antigenicity and glycoconjugate immunogenicity of the Streptococcus pneumoniae serotype 7F capsular polysaccharide.

Streptococcus pneumoniae is a bacterial pathogen causing diseases as severe as pneumonia, sepsis and meningitis. Commercial pneumococcal conjugate vaccines contain the 7F serotype, which is epidemiologically relevant and highly invasive. This serotype contains an O-acetyl group at the internal L-rhamnose of its polysaccharide repeating unit. Herein we report on the role of the O-acetyl moiety of 7F polysaccharide in both antigen recognition and the induction of a protective antibody response against 7F. Fully and partially de-O-acetylated 7F polysaccharides were chemically prepared and compared with the O-acetylated counterpart in their antigenicity and immunogenicity of their tetanus toxoid glycoconjugates. These comparative studies showed a slight but consistent decrease in the antigenicity for the fully de-O-acetylated polysaccharide, but not for the partly de-O-acetylated variant. The glycoconjugates derived from the O-acetylated and the fully de-O-acetylated polysaccharides had similar sizes and polysaccharide-to-protein ratio, and all proved both to be immunogenic and induce opsonophagocytic responses in mice. Nevertheless, the immune response elicited by the O-acetylated glycoconjugate was better in both quantity and quality, proving that the O-acetyl group is not strictly necessary but also not irrelevant for the antigenicity and immunogenicity of the 7F serotype polysaccharide and its glycoconjugates.

Serotype distribution and antimicrobial resistance of Streptococcus pneumoniae isolated from children in Japan, 2023

BackgroundThe prevalence of serotypes and antimicrobial resistance of Streptococcus pneumoniae was characterized among children thirteen years after the licensure of the pneumococcal conjugate vaccine (PCV) in Japan. MethodsA total of 353 pneumococcal isolates were collected from Japanese children between March and July 2023. All the isolates were serotyped using genetic methods and tested for susceptibility to 14 antimicrobial agents. ResultsAmong the 353 isolates, the prevalence rates of non-PCV13 and non-PCV20 serotypes were 96.9 % and 77.9 %, respectively, including the dominant non-PCV13/PCV20 serotypes 23A (16.1 %), 35B (15.3 %), 15A (10.5 %), 15C (9.3 %), and 34 (9.1 %), which accounted for 60.3 % of all isolates. The high non-susceptibility rates were observed for macrolides (erythromycin, azithromycin, and clarithromycin; ≥81.9 %) and tetracycline (80.7 %). Penicillin non-susceptibility and multidrug resistance (MDR) were detected in 49.9 % (6.8 % resistant and 43.1 % intermediate) and 68.3 % of the isolates, respectively. The three most common non-PCV13/PCV20 serotypes 15A, 23A, and 35B exhibited high prevalence rates of penicillin non-susceptibility (≥89.5 %) and MDR (≥81.5 %). Extensive drug resistance was observed in 10.5 % of all isolates belonging to six different serotypes (12F, 23A, 11A, 15A, 35B, and 15B) and in the non-encapsulated strains of S. pneumoniae. ConclusionsOur study revealed a higher prevalence of non-susceptibility to penicillin with MDR in the three most common non-PCV13/PCV20 serotypes 15A, 23A, and 35B, in Japan, suggesting their persistence in the PCV13 era.

Descriptive analysis of safety and immunogenicity profiles of a 15-valent pneumococcal conjugate vaccine between subcutaneous and intramuscular administration in a phase 1 study of healthy Japanese infants (V114-028)

IntroductionSubcutaneous (SC) administration is typically used for pediatric inactivated vaccines in Japan, whereas intramuscular (IM) administration is used outside Japan. We previously reported the safety and immunogenicity of V114, a 15-valent pneumococcal conjugate vaccine (PCV), administered subcutaneously and intramuscularly in a Japanese phase 1 study (V114-028). Here, we report secondary descriptive analyses on V114 groups of the study to further assess the safety and immunogenicity profiles of V114 between the administration routes. MethodsA total of 133 healthy Japanese infants were randomized to receive V114-SC (n = 44), V114-IM (n = 45), or PCV13-SC (n = 44) at approximately 3, 4, 5, and 12–15 months of age. Adverse events (AEs) from Days 1–14 post-vaccination and vaccine-related serious AEs from Day 1 to 1-month post-dose 4 were reported. Serotype-specific immunoglobulin G (IgG) responses were measured across the vaccination series. ResultsProportions of participants with solicited systemic AEs (irritability, somnolence, decreased appetite, and urticaria) and pyrexia were generally comparable between the groups. Compared with V114-SC, patients receiving V114-IM had a lower incidence of irritability and somnolence, and higher incidence of decreased appetite. Proportion of participants with solicited injection-site erythema was lower with V114-IM (82.2%) than V114-SC (100.0%). Those with other solicited injection-site AEs (induration, swelling, and pain) were generally comparable between the groups, with lower observed proportions with V114-IM. Serotype-specific IgG responses were also generally comparable between the groups, including at pre-toddler dose. ConclusionsThese results suggest the utility of IM administration as an option for V114 vaccination in Japanese infants.