Post‑pandemic pneumococcal carriage in Türkiye remains 19.6% across childhood. Direct protection against nasopharyngeal carriage was evident in children ≤ 10 y. Higher‑valency PCVs and enhanced genomic serotype surveillance are needed to address residual carriage and guide future immunization strategies. •Pneumococcal conjugate vaccines (PCVs) have substantially reduced invasive pneumococcal disease, but nasopharyngealcolonization persists due to serotype replacement. •After the COVID-19 pandemic, major shifts in respiratory pathogen epidemiology occurred, yet contemporary post-pandemicdata on pneumococcal carriage and serotype distribution remain scarce. •This is the first multicenter post-COVID pneumococcal carriage study in Türkiye covering the full 0-24-year age spectrum,showing that carriage remains stable at ~20%. •Direct vaccine protection against carriage is confined to children ≤10 years, with no measurable impact in adolescents or youngadults. Some vaccine serotypes and non-vaccine serotypes still dominate carriage, and higher-valency PCVs would markedlyimprove theoretical coverage.

Cost-effectiveness and return on investment of 20-valent pneumococcal conjugate vaccine use among adults in England: analysis from the societal perspective.

Vaccines are our best defence against infectious diseases, yet uptake of childhood immunisation programmes has consistently declined in the UK, with growing concerns around socioeconomic inequalities. Liverpool, in particular, demonstrated some of the lowest uptake rates in England since 2019. In response, the Health Equity Liverpool Project (HELP) implemented a hyper-localised community-led initiative between September 2023 and June 2024 to tackle vaccine hesitancy. Activities included outreach events and school-based engagement across nine sites within Liverpool. Despite promising qualitative evidence, the intervention's impact on childhood vaccine uptake has not yet been quantified. We aim to evaluate the population level impact of the HELP intervention on the uptake of five childhood vaccines (first and second doses of the measles, mumps and rubella vaccine (MMR1, MMR2), 6-in-1 vaccine (diphtheria, tetanus, pertussis, polio, haemophilus influenzae type b and hepatitis B), pneumococcal conjugate vaccine booster dose (PCV) and rotavirus vaccine) using synthetic control methods. We will analyse publicly available quarterly vaccine uptake data (between April 2019 and March 2025) from the Cover of Vaccination Evaluated Rapidly programme for general practices (GPs) in England. The intervention group will be defined as practices located within a 1 km radius of the intervention sites. A synthetic control group will be constructed using non-intervention GPs matched on pre-intervention vaccine uptake, and linked demographic, socioeconomic and healthcare capacity covariates. Primary outcomes are the uptake of MMR1 and MMR2 vaccines. Secondary outcomes include the uptake of 6-in-1, PCV and rotavirus vaccines. Average treatment effects will be estimated as the post-intervention difference in uptake between intervention and synthetic control groups. Sensitivity analyses will examine spillover effects, alternative spatial definitions of exposure, the biasing effect of concurrent interventions and the feasibility of analysis at small area neighbourhood level. This study will be conducted as part of the ReCITE project, which has received ethical approval from the Liverpool School of Tropical Medicine Research Ethics Committee (Reference: 24-018) and is funded by the UK Arts and Humanities Research Council (Project Number: AH/Z505341/1). Findings will be shared with the project funder and submitted for publication in a peer-reviewed journal.

While typhoid conjugate vaccines (TCV) offer promise for reducing risk in endemic settings, their population-level impact remains unclear. In 2022, Nepal introduced TCV nationally on the heels of the COVID-19 pandemic, which disrupted healthcare services, surveillance, and potentially typhoid transmission dynamics, complicating vaccine impact evaluation. We investigated the impact of TCV introduction amid shifting typhoid burden during the pandemic. We analyzed blood culture data from four Kathmandu Valley health facilities, comparing culture positivity for Salmonella Typhi across three periods: pre-pandemic (January 2018-March 2020); pandemic, pre-vaccine introduction (April 2020-March 2022); post-vaccine introduction (April 2022-April 2024). We used multivariable logistic regression to assess S. Typhi positivity, adjusting for month and site, stratified by TCV-eligible children and older, TCV-ineligible populations. Between January 2018 and April 2024, 62,236 blood cultures were performed. S. Typhi blood culture positivity decreased from 2.11% pre-pandemic to 0.59% during the pandemic (p < 0.001) and remained low at 0.69% after TCV introduction. Among TCV-eligible children (15 months to 15 years), odds of S. Typhi positivity during the pandemic were 47% lower than the pre-COVID period (aOR 0.53, 95% CI 0.29-0.90) and continued to decrease by 75% post-TCV introduction (aOR 0.25, 95% CI 0.11-0.55). In contrast, among vaccine-ineligible individuals (≥16 years), odds of positivity during the pandemic were 77% lower than the pre-COVID period (aOR 0.23, 95% CI 0.16-0.31) but increased by 59% following TCV rollout (aOR 1.59, 95% CI 1.14-2.27). Sensitivity analyses restricted to pathogen-positive cultures yielded similar results. S. Typhi blood culture positivity declined sharply during the pandemic before TCV introduction. The subsequent rollout of TCV substantially reduced typhoid burden in vaccine-eligible children; however, rising cases among older, vaccine-ineligible populations following the relaxation of pandemic measures highlights the need for additional control measures such as improved water and sanitation infrastructure and broader age eligibility for typhoid vaccination.

Background Slovakia has introduced pneumococcal conjugate vaccines (PCVs) in the national immunization program (NIP) since 2011. Recently licensed for use in the pediatric population in Europe, the 20-valent pneumococcal conjugate vaccine (PCV20) is poised to become a new potential standard of care (SoC) in the pediatric national immunization program (NIP). Therefore, this study aims to assess the cost-effectiveness and the clinical and economic outcomes of the PCV20 compared to PCV13 and PCV15 in Slovakian infants. Methods A decision-analytic Markov model was employed to estimate the cost-effectiveness of implementing PCV20 versus two lower-valent PCVs in Slovakian infants aged over 10 years. Health outcomes comprised cases of pneumococcal disease, life years, and quality-adjusted life years (QALY). Economic outcomes included vaccination- and disease-associated costs. Outcomes were evaluated for the entire population to capture full vaccine benefits (indirect effects). Epidemiological inputs were sourced from local surveillance reports or published literature. Direct and indirect vaccine effects (VE) were estimated from vaccine impact, effectiveness, and clinical studies of PCV7 and PCV13. Economic inputs were informed by local studies and 2024 Slovak national reimbursement cost. Comprehensive deterministic sensitivity analysis and scenario analyses were examined. The study assumed a willingness-to-pay threshold (WTP) of €40,377/QALY. Results Over 10 years, PCV20 3 + 1 was predicted to prevent over 810 invasive pneumococcal disease (IPD) cases, 885,000 pneumonia cases, 6,600 otitis media (OM) cases, and 16,600 disease-associated deaths compared with PCV13 2 + 1. The disease prevention subsequently resulted in €326.7 million direct medical costs savings, 96,430,859 additional QALYs gain and an ICER of €1,349/QALY. Comparable trends were observed versus PCV15 2 + 1, with PCV20 preventing more pneumococcal disease cases, providing greater additional QALYs, and being cost-effective under the prespecified threshold. Results were consistent across base case and scenario analyses. Conclusions Implementing PCV20 into the Slovakian pediatric NIP is projected to yield the most significant clinical and economic benefits compared to the two lower-valent PCVs, due to its more extensive protection against a broader range of pneumococcal serotypes. Despite an additional cost of dose and visit, PCV20 was estimated to be cost-effective at the Slovak WTP threshold versus other SoC options over a 10-year time horizon.

Extraintestinal pathogenic Escherichia coli (ExPEC) are a leading cause of human bloodstream infections (BSIs) in sub-Saharan Africa, yet few studies have characterized African strains implicated in BSI or explored their potential reservoirs. We enrolled febrile patients at 2 hospitals in Moshi, Tanzania, 2007-2019, and performed blood cultures. Whole-genome sequencing was conducted on E. coli originating from the bloodstream to characterize sequence types (STs), serotypes, and theoretical coverage of a 9-valent ExPEC polysaccharide conjugate vaccine (ExPEC9V). Separately, we evaluated 601 E. coli whole-genome sequences from humans, animals, and environmental sources in nearby communities. We assessed genetic relatedness between bloodstream and community isolates based on single-nucleotide polymorphisms and allele differences. Of 3046 participants receiving blood culture, 48 (0.2%) had BSI yielding 48 E. coli isolates. The median (range) age of participants with E. coli BSI was 40.7 (0.3-89.0) years, and 32 (68.1%) were female. We identified 16 STs including ST131 (n = 16, 33.3%), ST73 (n = 10, 20.8%), and ST69 (n = 6, 12.5%) and 19 O groups including O25 (n = 13, 27.1%), O6 (n = 10, 20.3%), O17 (n = 4, 8.3%), and O18 (n = 4, 8.3%). Theoretical coverage for an ExPEC9V was 72.9%. None of the bloodstream and community E. coli pairs were closely related. We found a high diversity of STs among E. coli human bloodstream isolates in Tanzania. Despite this diversity, we observed that an EXPEC9V in development would provide good coverage. Reservoir-attribution studies at finer spatial and temporal scales may better identify transmission networks and reservoirs of ExPECs.

ABSTRACT Background This study analyzed the health and economic outcomes of the 21-valent pneumococcal conjugate vaccine (PNEU-C-21; CAPVAXIVE®) compared to either PNEU-C-20 or PNEU-P-23. Cohorts in the cost-effectiveness analyses included vaccine-naïve 57- and 65-year-olds and vaccine-experienced 70-year-olds. Research design and methods A published Markov model simulated the movement of the Canadian population among four health states: healthy, pneumococcal disease (invasive pneumococcal disease and community-acquired pneumonia attributed to S. pneumoniae), post-meningitis sequelae, and death. The model was populated with published literature and publicly available databases and/or reports. Model inputs included demographic data, epidemiologic data, serotype distribution, vaccine effectiveness, costs, and health-related utilities. The model used a lifetime horizon and 1.5% discounting of costs and life years. Key outcomes included the following: cases, deaths, costs, and incremental cost-effectiveness ratios. Results The PNEU-C-21 strategy prevented substantially more cases and deaths when compared to the PNEU-C-20 or PNEU-P-23 strategies. For both vaccine-naïve cohorts, the ICERs were dominant for both PNEU-C-21 vs. PNEU-C-20 and PNEU-C-21 vs. PNEU-P-23; among adults aged 70 years, previously vaccinated with PNEU-P-23, PNEU-C-21 was dominant over PNEU-C-20. Conclusions These results demonstrate that PNEU-C-21 can prevent a substantial number of cases and deaths while remaining highly cost-effective over a range of inputs and scenarios in Canada.

BackgroundThe guidance on the vaccination schedule against pneumococcal disease (PD) in Brazil is carried out by the National Immunization Program (NIP) in the Unified Health System (SUS) in Brazil., through the immunization recommendations presented by the Reference Centers for Special Immunobiologicals (Centros de Referência para Imunobiológicos Especiais, CRIE). Currently, CRIE guidelines specify two types of population: the high-risk population, for which immunization with the pneumococcal conjugate vaccine 13, with at least two booster doses of the polysaccharide vaccine 23 (PPS-23), is indicated, and the at-risk population, currently receiving the complete vaccination schedule composed solely of PPS-23 doses. Our objective was to estimate the population size living with health conditions assigned as ‘at risk’ for PD by analyzing administrative data in Brazilian Public Health System (SUS).Box 1:At-Risk Groups as defined by the National Immunization Program in the Unified Health System in BrazilFigure 1:Number of distinct individuals at risk for pneumococcal disease by health condition, logarithmic scaleMethodsRetrospective analysis of the outpatient information system (Sistema de Informação Ambulatorial, DATASUS-SIA). Health conditions considered to be at risk are presented in Box 1. ICD-10 and procedure codes related to these health conditions and proxies of disease activity and severity were created. Encrypted identifiers in DATASUS-SIA were used to allow for the identification and counting of distinct individuals, to avoid double counting (i.e., same individuals being accounted for in different categories), from November 2021 to October 2023.ResultsA total of 1,608,659 distinct individuals at risk for PD were identified. Five categories accounted for most cases (98.5%), namely diabetes mellitus; incapacitating chronic neurological diseases; chronic nephropathies; chronic heart disease; and chronic lung diseases. (Figure 1). The lowest number of identified cases was for the group persistent moderate to severe asthma, for which the initial number of distinct identified individuals was 555,103 but only 491 (8.9%) of cases fulfilled proxies for disease activity and severity.ConclusionTo the best of our knowledge, this is the first study to provide estimates of the at-risk population size for PD in the SUS in Brazil. Such estimate is crucial to allow for future assessment of vaccination coverage rates and to underpin the design of new immunization programs.DisclosuresRicardo Macarini Ferreira, Md/ MBA, Pfizer Brazil: Employee Daniela V. Pachito, MD PhD MBA, Pfizer: Employee|Pfizer: Stocks/Bonds (Private Company) Paulo Almeida, PhD, Pfizer Brazil: Employee

BackgroundAcute mastoiditis (AM) is a complication of otitis media. The most common cause is Streptococcus pneumoniae. The incidence of invasive pneumococcal infections has decreased following the introduction of PCV-7 in 2000 and PCV-13 in 2010. We evaluated the changes in the incidence, bacteriology and complications of AM following introduction of PCV-7 and PCV-13.MethodsA retrospective review of medical records during 19-year period (2000-2018). AM was defined as a suppurative infection of mastoid air cells with symptoms of less than 3 weeks.ResultsWe identified 242 children with AM: 138 in the first period (2000 to 2010): PCV-7 and 104 in the second period (2011 to 2018): PCV-13. No significant change in AM incidence was noted: 11.0 cases/10,000 admissions in the first period and 8 cases/10,000 admissions in the second (p=0.31). Ages ranged from 3 months to 18 years (median 5.6 years). Symptoms included fever (52%), ear pain (63.6%) and mastoid tenderness (64.9%). Prior antibiotics were prescribed to 37.6%. Surgery was performed on 52.1%. Cultures from 125 patients showed S. pneumoniae (29.6%), S. pyogenes (17.6%), P. aeruginosa (16.8%), S. aureus (13.6%). Two had complicated AM due to Fusobacterium necrophorum. During the second period, S. pneumoniae was detected on 14/46 (34.8%) compared to 21/79 (21.1%) in the first (p=0.417). Partial or complete PCV vaccination was documented in 89 patients including 13/37 who had S. pneumoniae culture-positive AM. Most common parenteral antibiotics used were: IV ceftriaxone (64.5%), IV clindamycin (42.1%), IV ampicillin/sulbactam (19.8%). Most common oral antibiotics: amoxicillin-clavulanate (38%), clindamycin (20.2%) and amoxicillin (8.3%). Complications included bony erosive changes (mastoid/temporal bone) in 78, soft tissue abscesses in 39, venous sinus thrombosis in 10, facial nerve palsy in 6, intracranial extension in 7 patients, 6 of which in the second period.ConclusionDespite a decrease of invasive pneumococcal infections post PCV-7, the incidence of AM in our pediatric population remained unchanged after PCV-13 introduction with many complications. The role of the updated pneumococcal conjugate vaccines on AM incidence needs further evaluation.DisclosuresAll Authors: No reported disclosures

Abstract Background The 20-valent pneumococcal conjugate vaccine (PCV20) was licensed by the FDA in 2021 for the prevention of vaccine type (VT) invasive pneumococcal disease (IPD) and pneumococcal pneumonia based on immunologic non-inferiority criteria. No clinical efficacy or vaccine effectiveness (VE) data has been reported for PCV20. The aim of this study was to evaluate age-group PCV20 VE against all IPD and all-cause pneumonia (ACP) among older adults in the US. Methods In this retrospective time-segment design, individuals age ≥65 years were followed through the Medicare database from July 2022 to June 2024 for the first episode of all IPD (VT and non-VT) and ACP based on ICD-10-CM coding. We compared PCV20 vaccinated to unvaccinated adults with Medicare insurance for ≥1 year prior, excluding those who received 23-valent pneumococcal polysaccharide vaccine (PPSV23) &amp;lt; 2 years, PCV13 &amp;lt; 5 years, PCV20, or PCV15 prior to the start of study follow-up. The cohort was stratified by age group (65-74, 75-84, ≥85 years). Inverse probability weighting was used to control for confounding and dropout. Cox models estimated hazard ratios (HR) and VE was calculated as (1 – HR) x 100%. The weighted vaccine preventable disease incidence rate (IR)(VPDI) per 100K person-years (PY) was calculated as (IRunvaccinated – IRvaccinated). Results 16.5 million adults were included, of whom 12.2% received PCV20 during follow-up. After weighting and compared to individuals with PCV20-unvaccinated segments, a higher proportion of individuals contributing vaccinated time had &amp;gt;5 outpatient visits in the prior year and had received a PPSV23, PCV13, or COVID-19 vaccine (Table 1). PCV20 VE against all IPD was 25.6% among adults ≥65 years of age overall and 35.4%, 24.0%, and 16.6% among adults 65-74, 75-84, and ≥85 years of age, respectively (Table 2). PCV20 VE against ACP was 15.2% among adults ≥65 years of age overall and 20.2%, 15.9%, and 12.5% among adults 65-74, 75-84, and ≥85 years of age, respectively (Table 2). Among adults ≥65 years of age overall, PCV20 vaccination prevented 12.5 cases of IPD and 262.0 cases of ACP per 100K PY (Table 3). Conclusion This study presents the first real-world age-group specific estimates of PCV20 VE and confirms PCV20 effectiveness against IPD and ACP among adults 65-74, 75-84, and ≥85 years of age. Disclosures Amanda C. Miles, MPH, Pfizer: Employee of Pfizer Inc.|Pfizer: Stocks/Bonds (Public Company) Lindsay Grant, PhD, MPH, Pfizer: Employee|Pfizer: Stocks/Bonds (Private Company) Jelena Vojicic, MD, Pfizer Inc.: Employee|Pfizer Inc.: Stocks/Bonds (Public Company)|Pfizer Inc.: Stocks/Bonds (Public Company) Jeffrey T. Vietri, PhD, Pfizer Inc: Employment|Pfizer Inc: Stocks/Bonds (Public Company) Summer rosenstock, PhD, MHS, Pfizer: Stocks/Bonds (Public Company) Huihua Li, MS, MD, Pfizer Pharmaceutical: employee|Pfizer Pharmaceutical: Stocks/Bonds (Public Company) Alison E. Randall, MPH, PMP, Pfizer: Employment|Pfizer: Stocks/Bonds (Public Company) Bobby Zhao, PhD, Pfizer: Advisor/Consultant|Pfizer: Employee of Genesis Research Group, which has received consulting fees from Pfizer Inc. Anan Zhou, MPH, Pfizer Inc.: Employee of Genesis Research Group, which has received consulting fees from Pfizer Inc. Christian Theilacker, MD, DTM&amp;H, Pfizer Inc: Stocks/Bonds (Public Company)|Pfizer Inc: Stocks/Bonds (Public Company) Jennifer Moisi, PhD, Pfizer Vaccines: Employer|Pfizer Vaccines: Stocks/Bonds (Public Company) Luis Jodar, PhD, Pfizer Inc: Stocks/Bonds (Public Company) Paul Palmer, PhD, Pfizer Inc: Employee|Pfizer Inc: Stocks/Bonds (Public Company) Alejandro D. Cane, MD, PhD, Pfizer Inc.: All authors are employees of Pfizer Inc. and may hold stock and/or stock options of Pfizer Inc. Paula Peyrani, MD, Pfizer, Inc: Employee|Pfizer, Inc: Stocks/Bonds (Public Company)

BackgroundIn South Korea, the 10-valent and 13-valent pneumococcal conjugate vaccines (PCVs) have been part of the national immunization program since 2014, and 15-valent was recently introduced in 2024. To understand the current dynamics of pneumococcal serotype distribution in South Korea, we investigated the genotypes of Streptococcus pneumoniae isolates from pediatric invasive pneumococcal disease (IPD).eBURST diagram of multilocus sequence typing from invasive pneumococcal isolates, from 2016 to 2023MethodsIPD cases from children under 19 years of age were collected through a prospective hospital-based surveillance at 20 hospitals between 2016 and 2023 in South Korea. Serotypes were determined using the Quellung reaction. Genotypes were determined by MLST. Alleles and sequence types were submitted to the web database for assignment. The eBURST diagram was created using the Phyloviz program. Distribution of serotype and genotype was compared between the pre-COVID-19 period (2016-2019) and the during/post-COVID-19 period (2020-2023).ResultsAmong the 187 cases with determined serotypes, the most common were 10A (21.9%), 15C (11.8%), 15A (9.1%), 15B (8.0%), 19A (7.5%), and 23B (5.9%). Compared to the pre-COVID-19 period, serotype 23B increased from 0.9% to 14.3% (P < 0.001) and serotype 6C from 0.9% to 7.1% (P = 0.029), while serotype 10A declined from 27.4% to 12.9% (P = 0.018).The most common clonal complex (CC) was CC166 (24.1%), followed by CC1263 (20.9%), CC320 (12.8%), and CC81 (9.6%). The most prevalent sequence type (ST) was ST11189 (19.3%), followed by ST166 (16.6%). The decrease in serotype 10A was associated with a reduction in the dominant ST11189, while the increases in serotypes 23B and 6C were linked to ST166 and ST13556, respectively, in the during/post-COVID-19 period.ConclusionA notable shift in serotype and genotype distribution of pediatric IPD has occurred in South Korea, with the emergence of serotype 23B-CC166 and serotype 6C-CC81. These findings underscore the need to consider emerging non-vaccine serotypes in future immunization strategies to prevent IPD in children.DisclosuresAll Authors: No reported disclosures

Patients with inflammatory bowel disease (IBD) are at higher risk of pneumonia due to the disease itself and the use of immune-modifying medications. We conducted a retrospective analysis of TriNetX US Collaborative Network data on patients with IBD who received the 20-valent pneumococcal conjugate vaccine (PCV20). Propensity score matching was performed to adjust for differences in demographics and pneumonia-related risk factors. After propensity score matching, 12,796 patients were included in the analysis. The mean ages of the vaccinated and control groups were 55.2 ± 16.3 and 55.8 ± 17.1years, respectively, with females comprising 53% of each group. The most commonly prescribed IBD therapies across both cohorts included prednisone, methylprednisolone, budesonide, and adalimumab. Compared to the control group, patients who received PCV20 experienced significantly lower risks of pneumonia, acute respiratory failure, hospital admissions, ICU admissions, and all-cause mortality. These findings align with current recommendations supporting pneumococcal vaccination in adult patients with IBD and highlight the importance of further studies to clarify the extent of vaccine-related benefit in this population.

Trends in Streptococcus pneumoniae serotypes and antimicrobial resistance in Italy (2007-2023): A mixed-effects model analysis of invasive pneumococcal disease.

Meningococcal disease is a serious bacterial infection caused by Neisseria meningitidis. Serogroups B, C, W, and Y cause the majority of cases of this disease in the United States. These serogroups are targeted by different meningococcal vaccines available in the United States. Two quadrivalent (serogroups A, C, W, and Y) meningococcal conjugate vaccines (MenACWY) (MenACWY-CRM [Menveo, GSK] and MenACWY-TT [MenQuadfi, Sanofi Pasteur]) and two serogroup B meningococcal vaccines (MenB) (MenB-4C [Bexsero, GSK] and MenB-FHbp [Trumenba, Pfizer]) are licensed for use in the United States and recommended by CDC's Advisory Committee on Immunization Practices (ACIP). Indications for MenACWY and MenB vaccination have not changed since indications for their use were published in 2020. A pentavalent (serogroups A, B, C, W, and Y) meningococcal vaccine (MenABCWY) (MenACWY-TT/MenB-FHbp [Penbraya, Pfizer]) has been licensed and recommended for use since October 2023. On February 14, 2025, the Food and Drug Administration licensed a second pentavalent MenABCWY vaccine (MenACWY-CRM/MenB-4C [Penmenvy, GSK]) for prevention of invasive disease caused by N. meningitidis serogroups A, B, C, W, and Y in persons aged 10-25 years, the same indication for which MenACWY-TT/MenB-FHbp is licensed. On April 16, 2025, ACIP recommended that MenACWY-CRM/MenB-4C may be used when both MenACWY and MenB are indicated at the same visit for 1) healthy persons aged 16-23 years (routine schedule) when shared clinical decision-making favors administration of MenB vaccine and 2) persons aged ≥10 years who are at increased risk for meningococcal disease (e.g., because of persistent complement deficiencies, complement inhibitor use, or functional or anatomic asplenia). Different manufacturers' serogroup B-targeting vaccines are not interchangeable; therefore, when MenACWY-CRM/MenB-4C is used, MenB-4C should be used for the other MenB doses. This report summarizes evidence considered for these recommendations and provides clinical guidance for the use of MenACWY-CRM/MenB-4C.

Safety and coverage of Pneumosil pneumococcal polysaccharide conjugate vaccine (10-valent PCV) in a camp for internally displaced persons in Somaliland.

The development of effective vaccines against tumor-associated MUC1 (taMUC1) glycopeptide antigens remains a significant challenge due to their poor intrinsic immunogenicity. A key limitation in conjugate vaccine design lies in the structural alterations that occur upon carrier protein functionalization, which can reduce the accessibility of surface-conjugated antigens, ultimately compromising antigen presentation. In this study, we present a semi-synthetic vaccine platform in which taMUC1 glycopeptides are displayed on synthetic cyclopeptide scaffolds-configured either as monovalent or clustered tetravalent platforms-and subsequently grafted onto solvent-exposed amine residues of the CRM197 protein via squaramide linkages. These conjugates were purified under denaturing conditions via reverse phase HPLC and evaluated in vivo through mouse immunization studies. Despite differences in antigen valency and glycopeptide loading per protein, both conjugates induced comparable levels of antigen-specific IgGs and CD4+/CD8+ T-cell activation when co-administered with the QS-21 adjuvant. Notably, although antibody titers were similar, post-immunization sera from mice immunized with the tetravalent conjugate plus the QS-21 adjuvant showed enhanced reactivity toward native taMUC1 expressed on MCF7 cancer cells, suggesting improved epitope recognition. These results highlight the impact of scaffold design, antigen display and adjuvantation on vaccine efficacy and establish a promising platform for the development of conjugate vaccines targeting weak tumor-associated antigens.

Polysaccharide conjugate vaccines: From historical milestones to future strategies.

Post-pandemic increase in pediatric invasive pneumococcal disease driven by serotype 3.

Pneumococcal meningitis in Mexico. Serotype distribution and antimicrobial resistance before and after the introduction of pneumococcal conjugate vaccines in pediatric patients. Results from the GIVEBPVac group.

Evaluating the implementation of the 20-valent pneumococcal conjugate vaccine for paediatric immunization in Australia.