Optimization of the Process for Preparing Bivalent Polysaccharide Conjugates to Develop Multivalent Conjugate Vaccines against Streptococcus pneumoniae or Neisseria meningitidis and Comparison with the Corresponding Licensed Vaccines in Animal Models

Objective:This study aimed to describe,optimize and evaluate a method for preparing multivalent conjugate vaccines by simultaneous conjugation of two different bacterial capsular polysaccharides(CPs)with tetanus toxoid(TT)as bivalent conjugates.Methods:Different molecular weights(MWs)of polysaccharides,activating agents and capsular polysaccharide/protein(CP/Pro)ratio that may influence conjugation and immunogenicity were investigated and optimized to prepare the bivalent conjugate bulk.Using the described method and optimized parameters,a 20-valent pneumococcal conjugate vaccine and a bivalent meningococcal vaccine were developed and their effectiveness was compared to that of corresponding licensed vaccines in rabbit or mouse models.Results:The immunogenicity test revealed that polysaccharides with lower MWs were better for Pn1-TT-Pn3 and MenA-TT-MenC,while higher MWs were superior for Pn4-TT-Pn14,Pn6A-TT-Pn6B,Pn7F-TT-Pn23F and Pn8-TT-Pn11A.For activating polysaccharides,1-cyano-4-dimethylaminopyridinium tetrafluoroborate(CDAP)was superior to cyanogen bromide(CNBr),but for Pn1,Pn3 and MenC,N-(3-dimethylaminopropyl)-N’-ethylcarbodiimide hydrochloride(EDAC)was the most suitable option.For Pn6A-TT-Pn6B and Pn8-TT-Pn11A,rabbits immunized with bivalent conjugates with lower CP/Pro ratios showed significantly stronger CP-specific antibody responses,while for Pn4-TT-Pn14,higher CP/Pro ratio was better.Instead of interfering with the respective immunological activity,our bivalent conjugates usually induced higher IgG titers than their monovalent counterparts.Conclusion:The result indicated that the described conjugation technique was feasible and efficacious to prepare glycoconjugate vaccines,laying a solid foundation for developing extended-valent multivalent or combined conjugate vaccines without potentially decreased immune function.

Adherence to Advisory Committee on Immunization Practices in diabetes mellitus patients in Saudi Arabia:A multicenter retrospective study

BACKGROUND Patients with diabetes mellitus(DM)are predisposed to an increased risk of infection signifying the importance of vaccination to protect against its potentially severe complications.The Centers for Disease Control and Prevention/Advisory Committee on Immunization Practices(CDC/ACIP)issued immunization recommendations to protect this patient population.AIM To assess the adherence of patients with DM to the CDC/ACIP immunization recommendations in Saudi Arabia and to identify the factors associated with the vaccine adherence rate.METHODS An observational retrospective study conducted in 2023 was used to collect data on the vaccination records from 13 diabetes care centers in Saudi Arabia with 1000 eligible patients in phase I with data collected through chart review and 709 patients in phase II through online survey.RESULTS Among participants,10.01%(n=71)had never received any vaccine,while 85.89%(n=609)received at least one dose of the coronavirus disease 2019(COVID-19)vaccine,and 34.83%(n=247)had received the annual influenza vaccine.Only 2.96%(n=21),2.11%(n=15),and 1.12%(n=8)received herpes zoster,tetanus,diphtheria,and pertussis(Tdap),and human papillomavirus(HPV)vaccines,respectively.For patients with DM in Saudi Arabia,the rate of vaccination for annual influenza and COVID-19 vaccines was higher compared to other vaccinations such as herpes zoster,Tdap,pneumococcal,and HPV.Factors such as vaccine recommendations provided by family physicians or specialists,site of care,income level,DM-related hospitalization history,residency site,hemoglobin A1c(HbA1c)level,and health sector type can significantly influence the vaccination rate in patients with DM.Among non-vaccinated patients with DM,the most reported barriers were lack of knowledge and fear of side effects.This signifies the need for large-scale research in this area to identify additional factors that might facilitate adherence to CDC/ACIP vaccine recommendations in patients with DM.CONCLUSION In Saudi Arabia,patients with DM showed higher vaccination rates for annual influenza and COVID-19 vaccines compared to other vaccinations such as herpes zoster,Tdap,pneumococcal,and HPV.Factors such as vaccine recommendations provided by family physicians or specialists,the site of care,income level,DM-related hospitalization history,residency site,HbA1c level,and health sector type can significantly influence the vaccination rate in patients with DM.

Effectiveness of 7-valent pneumococcal conjugate vaccine: A meta-analysis of post-marketing studies

AIM:To investigate the 7-valent pneumococcalconjugate vaccine(PCV7)effectiveness.METHODS:A systematic literature review of studies which evaluated the effectiveness of PCV7 vaccine was performed searching the keyword"heptavalent pneumococcal conjugate vaccine"in PubM ed and Scopus until March 16,2013.The selection of potential eligible articles was done by two researchers independently on the basis of abstract and title and only post-marketing studies were included in the systematic review.Data extraction was carried out by two researchers with respect to invasive pneumococcal diseases due to both all and vaccine serotypes in pre-vaccine and postvaccine periods in children less than 5 years.Results of studies which were considered suitable for meta-analysis were combined by means of relative risk(RR)with95%CI.Vaccine effectiveness was calculated as(1-RR)×100.Heterogeneity was assessed by I2 and a random effects model was used to combine data in the case of heterogeneity.RevM an 5 was used to pool data.RESULTS:On the whole,757 eligible papers were identified from the literature search in PubM ed and Scopus.Of them,62 were finally considered in the systematic review and 38 were included in the meta-analysis.In all post-marketing studies included in the systematic review the incidence of invasive pneumococcal diseases due to vaccine serotypes declined significantly with the exception of few studies showing stability or a slight,but not significant,increase.Furthermore most of studies highlighted also a reduction in the incidence of invasive pneumococcal diseases due to all serotypes.With regards to meta-analysis,a random effects model was used to combine data because of the high heterogeneity.Data combination showed that the effectiveness of PCV7in reducing invasive pneumococcal diseases due to vaccine serotypes and to all serotypes was 84%(95%CI:74%-90%)and 53%(95%CI:46%-59%)respectively.These results are confirmatory with respect to the efficacy of PCV7 against invasive pneumococcal diseasesdue to vaccine serotypes.CONCLUSION:PCV7 implementation determines a significant decrease of invasive pneumococcal diseases.

Increased Susceptibility to Pneumococcal Disease in Sjogren Syndrome Patients

Susceptibility to pneumococcal infections in Sj?gren syndrome (SS)―an autoimmune inflammatory disease―patients is not well known, although these patients frequently develop respiratory diseases. The relative risk of developing pneumococcal disease in SS patients versus diabetes mellitus type 2 (DM-2) patients, matched by age, gender, and length of enrolment was studied. From January 1998 to September 2013 the records of Donostia University Hospital were analyzed, which among other patient’s data includes: number and type of hospital admissions and number and type of laboratory determinations. Streptococcus pneumoniae isolates of the same serotype causing recurrent infections were characterized by PFGE. The study comprised 127 patients in the SS group (69 primary and 58 secondary) and 127 in the DM-2 group as control. In 12 SS patients, (9.4%) 22 pneumococcal disease episodes were detected. Two patients (1.6%) with a single episode each one were observed among DM-2 patients, p = 0.01, RR for SS patients 6 (95% CI 1.4 to 26.3). No differences could be demonstrated between the two groups of patients in infections caused by Staphylococcus aureus or Streptococcus agalactiae. Most pneumococcal serotypes in SS patients belonged to the 13-valent (50%) and 23-valent (75%) anti-pneumococcal vaccine. SS patients are associated with and increased risk of suffering from pneumococcal disease. Vaccination should be considered in this group of patients.

贵州省基于离散选择实验的13价肺炎球菌结合疫苗的选择偏好研究

目的了解儿童家长对13价肺炎球菌结合疫苗(13-valent pneumococcal conjugate vaccine,PCV13)的选择偏好,分析不同人群的偏好异质性,为疫苗的合理推广和使用提供建议。方法基于离散选择实验,在多阶段随机整群抽样的基础上,纳入2月龄至10周岁儿童的家长,使用电子问卷对儿童家长进行面对面调查,利用混合logit模型来评估受访者对PCV13的选择偏好。结果此次调查共收到有效问卷1476份,通过一致性检验的问卷1175份。所有疫苗属性对选择偏好均有统计学意义,有效性和保护时长是儿童家长更注重的疫苗属性。包含交互效应的混合logit模型显示,大专及以上学历的家长更偏好90%有效性以及低不良事件发生率的疫苗,家庭人均月收入大于3000元的家庭更偏好进口疫苗。在为儿童选择PCV13方面,儿童家长更愿意为疫苗高有效性和10年的保护时长支付更多的费用,普遍更偏好国产疫苗和全程接种费用低的疫苗。结论研究结果将为后续相关部门对于PCV13的管理决策提供数据支撑,并且为疫苗生产方提供参考,有助于合理推广PCV13并提高其接受度。

13-Valent pneumococcal conjugate vaccines vaccination innovative strategy in Weifang City,China:a case study

The World Health Organization(WHO)prioritizes pneumococcal disease as a vaccine-preventable disease and recommends the inclusion of pneumococcal conjugate vaccines(PCV)in national immunization programs worldwide.However,PCV is not included in the National Immunization Program in China and has low vaccination coverage due to its high cost.To address this,Weifang City implemented an innovative strategy for a 13-valent PCV(PCV13)on June 1,2021.This strategy aimed to provide one dose of PCV13 free of charge for children aged 6 months to 2 years in registered households and to adopt a commercial insurance model with one dose of PCV13 free of charge in 2023 for children over 2 years old.The Health Commission of Weifang and other departments conducted a comprehensive investigation and considered various factors,such as vaccine efectiveness,safety,accessibility,vaccine price,and immunization schedules,for eligible children(under 5 years old).Stakeholder opinions were also solicited before implementing the policy.The Commission negotiated with various vaccine manufacturers to maximize its negotiating power and reduce vaccine prices.The implementation plan was introduced under the Healthy Weifang Strategy.Following the implementation of this strategy,the full course of vaccination coverage increased signifcantly from 0.67 to 6.59%.However,vaccination coverage is still lower than that in developed countries.Weifang’s PCV13 vaccination innovative strategy is the frst of its kind in Chinese mainland and is an active pilot of non-immunization program vaccination strategies.To further promote PCV13 vaccination,Weifang City should continue to implement this strategy and explore appropriate fnancing channels.Regions with higher levels of economic development can innovate the implementation of vaccine programs,broaden fnancing channels,improve accessibility to vaccination services,and advocate for more localities to incorporate PCV13 into locally expanded immunization programs or people-benefting projects.A monitoring and evaluation system should also be established to evaluate implementation efects.

Accelerating Pneumococcal Conjugate Vaccine introductions in Indonesia:key learnings from 2017 to 2022

Despite high pneumococcal disease and economic burden in Indonesia and interest to introduce pneumococcal conjugate vaccine (PCV), there were challenges in establishing a comprehensive strategy to accelerate and enable the introduction in country in the early 2010s. Starting in 2017, Clinton Health Access Initiative and partners supported the government of Indonesia with evidence-based decision-making and implementation support for introducing PCV into the routine immunization program. Indonesia has since accelerated PCV roll out, with nationwide reach achieved in 2022. On the path to PCV introduction, several challenges were observed that impacted decision making on whether and on how to optimally roll out PCV, resulting in significant introduction delays;including (1) a complex country context with a devolved government structure, fragmented domestic funding streams, and an imminent transition out of major immunization donor (Gavi) support;(2) strong preference to use domestically sourced products, with limited experience accessing global pooled procurement mechanism including for vaccines;and (3) concerns around programmatic feasibility and sustainability. This case study documents key insights into the challenges experienced and how those were systematically addressed to accelerate new vaccine introduction in Indonesia, with support from local and global stakeholders over time. The learnings would be beneficial for other countries yet to introduce critical new vaccines, in particular those with similar archetype as Indonesia e.g., middle-income countries with domestic manufacturing capacity and/or countries recently transitioning out of Gavi support.

Novel polysaccharide-protein conjugates provide an immunogenic 13-valent pneumococcal conjugate vaccine for S.pneumoniae

Pneumonia remains the single leading cause of childhood death worldwide.Despite the commercial availability of multiple pneumococcal conjugate vaccines(PCVs),high dosage cost and supply shortages prevent PCV delivery to much of the developing world.The current work presents high-yield pneumococcal conjugates that are immunogenic in animals and suitable for use in human vaccine development.The 13-valent pneumococcal conjugate vaccine(PCV-13)investigated in this research incorporated serotypes 1,3,4,5,6A,6B,7F,9V,14,18C,19A,19F,and 23F.Pneumococcal polysaccharides(PnPSs)and CRM197 carrier protein were produced and purified in-house,and used to prepare PnPS-CRM conjugates using unique,cyanide-free,in vacuo glycation conjugation methods.In vitro characterization confirmed the generation of higher molecular weight PnPS-CRM conjugates low in free protein.In vivo animal studies were performed to compare PnuVax's PCV-13 to the commercially available PCV-13,Prevnar®13(Pfizer,USA).A boost dose was provided to all groups post-dose 1 at t?14 days.Post-dose 2 results at t?28 days showed that all 13 serotypes in PnuVax's PCV-13 were boostable.Per serotype IgG GMCs demonstrated that PnuVax's PCV-13 is immunogenic for all 13 serotypes,with 10 of the 13 serotypes statistically the same or higher than Prevnar®13 post-dose 2.As a result,the novel polysaccharideprotein conjugates developed in this work are highly promising for use in human PCV development.The in vacuo conjugation technique applied in this work could also be readily adapted to develop many other conjugate vaccines.

Assessment of humoral immunity and nutritionally essential trace elements in steady-state sickle cell disease Nigerian children before and after Prevenar 13 pneumococcal vaccination

Background:Children with sickle cell disease(SCD)are particularly prone to pneumococcal infection and administration of Prevenar 13 pneumococcal vaccine in Nigerian children with SCD is yet to be wide spread.This call for the need to study humoral immune responses stimulated by Prevenar 13 pneumococcal vaccine in SCD children to confirm the benefit or otherwise for the use of Prevenar 13 pneumococcal vaccine.Method:The levels of humoral(innate and adaptive)immune factors and associated nutritionally essential trace elements were determined following Prevenar 13 pneumococcal vaccination of 23 Nigerian children with SCD.Serum innate humoral immune factors[Complement factors(C1q and C4),transferrin,ferritin,and C-reactive protein(CRP)]and adaptive humoral immune factors[IgG,IgA,IgM,and IgE]were determined using ELISA.Nutritionally essential trace elements such as iron(Fe),copper(Cu),and zinc(Zn)were measured also using an atomic absorption spectrophotometer.Results:The serum levels of certain innate humoral immune factors(ferritin,CRP,and C4),only one adaptive humoral immune factors(IgE),and essential trace elements(Fe,Zn,and Cu)were significantly elevated in children with SCD post Prevenar 13 pneumococcal vaccination when compared to prevaccination levels.Conclusion:Vaccination of children with SCD with Prevenar 13 pneumococcal vaccine was associated with increased levels of more innate humoral immune factors than adaptive factors.This study thus supports the administration of Prevenar 13 pneumococcal vaccination to children with SCD.