Expert Review of Vaccines最新文献

Introduction: Typhoid fever is widespread in developing countries. Most typhoid vaccines have gone into some disrepute for their substantial side effects and low efficacy. The latest typhoid vaccines use Salmonella's Vi-capsular polysaccharide (Vi-CPS) conjugated to a protein carrier. The WHO recommends a single typhoid conjugate vaccine (TCV) dose at six months in endemic countries. However, this schedule is contested.

Areas covered: The molecular structure of Vi-CPS, emerging Vi capsule variants, the impact of de-O acetylation on vaccine immunogenicity, the key features of an effective Vi-PS conjugate vaccine, the immunological correlates of protection, the impact of boosting by a TCV on Vi-antibodies, and knowledge gaps were examined. We have also reviewed TCV efficacy and durability data. Our analysis shows that the vaccines are effective, although immunity wanes after five years, especially in children under two. We also offered ways to improve TCV efficacy and briefly discussed new typhoid vaccine development.

Expert opinion: We believe the TCV schedule necessitates revision. Extending the primary immunization age or incorporating a booster upon school enrollment are reasonable alternatives. Region-specific or universal modifications require further deliberation.

Background: China implemented diverse varicella vaccination strategies from 2012 to 2022, with unclear protective effects. The study aimed to evaluate the effects of two varicella vaccination (VarV) (the two-dose self-paid VarV and the two-dose free VarV) strategies implemented in Guangdong Province, China.

Research design and methods: We collected data on varicella cases and doses administered to children aged 0-14 in Guangzhou, Shenzhen, and Foshan from 2012 to 2022. Using Bayesian Structured Time Series (BSTS) model, we estimated the effects of the two VarV strategies in Guangzhou and Shenzhen starting from 2018, by referencing Foshan.

Results: Post-implementation of the two-dose self-paid VarV strategy 36,749 (95% CI: 29070, 44428) and 24,179 (95% CI: 16400, 31958) varicella cases were averted in Guangzhou and Shenzhen, with a protection rate of 41.8% (95% CI: 36.3%, 46.5%) and 38.9% (95% CI: 30.2%, 45.7%), respectively. After the adoption of the two-dose free VarV strategy, a substantial relative protection rate of 64.2% (95% CI: 58.0%, 68.7%) in varicella cases was observed in Shenzhen, with 38,828 (95% CI: 29979, 47677) cases averted by 2022.

Conclusions: The two-dose VarV strategies have proven highly effective in reducing varicella incidence. The experience in Shenzhen underscores the benefits of a two-dose free VarV strategy.

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.

Introduction: Pertussis poses a significant threat to infants under six months due to their immature immune systems, limited maternal antibody protection, and constraints in the vaccination schedule. Despite vaccination efforts, this group remains highly susceptible to severe complications. Addressing these challenges is crucial for improving the health outcomes of infants in China.

Areas covered: This review examines the primary challenges in preventing pertussis infections among infants under six months in China, focusing on factors such as underdeveloped immune system and inadequate maternal antibody protection. It analyzes limitations in current vaccination strategies and the impact of socio-cultural factors, healthcare resource distribution, and surveillance inadequacies. A comprehensive literature search was conducted to identify potential solutions, including enhancing maternal immunization, adjusting early vaccination strategies, increasing vaccine coverage, and developing new vaccines. The review synthesizes current research findings and data to provide a detailed overview of these issues.

Expert opinion: Infants under six months are particularly vulnerable to pertussis. Early and effective prevention strategies, such as enhanced maternal immunization and adjusted vaccination schedules, are needed. Increasing vaccine coverage and developing safer, more immunogenic vaccines are essential. Policymakers should prioritize these measures to reduce pertussis incidence and complications among infants in China.

Introduction: Vaccination rates in Italian children must be substantially increased to control the transmission of seasonal influenza and mitigate the associated socio-economic burden. This work aimed to describe strategies to improve the effectiveness and reach of pediatric influenza vaccination campaigns in Italy.

Areas covered: Based on a literature review, influencing factors and potential strategies to enhance vaccination coverage were explored, focusing on settings, logistics, and communication aspects.

Expert opinion: School-based interventions should be deeply implemented in Italy by offering a cost-effective and safe approach to vaccination and successfully overcoming socio-economic and cultural challenges. Scheduled educational programs and institution-supported childhood influenza vaccination awareness campaigns that thoroughly inform about the risk of influenza and its socio-economic consequences, counter vaccine hesitancy, and discuss the benefits of vaccination are desirable, thus concretely prompting all children, families, and healthcare professionals to get vaccinated. Digitalizing procedures could lead to improved adherence by healthcare professionals to immunization programs. Nationwide implementation of these strategies would establish a robust, sustainable system for pediatric influenza vaccination. This would significantly increase childhood vaccination rates, leading to improved disease control and substantially reducing the overall national burden of influenza.

Introduction: To address the cervical cancer burden globally, the World Health Organization and European Union released strategies to facilitate HPV-related cancers prevention, including cervical cancer elimination. This research assessed European country level readiness to achieve cervical cancer elimination by adhering to such strategies.

Areas covered: Readiness for cervical cancer elimination was assessed across a range of guiding questions relevant to three defined key domains: vaccination, screening, and treatment, each with two sub-domains focusing on decision making and implementation efforts. Publicly available data sources were used to inform the scoring across domains, to tier countries into either high, moderate-high, moderate-low, and low readiness archetypes.Key parameters identified associated with the high readiness archetype were high vaccination coverage rates (>70%), availability of gender neutral and catch-up vaccination, school-based vaccination availability, organized screening programs, use of HPV DNA primary screening tests, and data surveillance.

Expert opinion: Our analysis highlights significant variability in decision making and implementation of vaccination, screening, and treatment programmes across Europe. Country scores expose the need for a multifaceted approach to achieve cervical cancer elimination in Europe, encompassing solid decision making commitments, implementation of these commitments, and the ability to collect, surveil, and apply the data use accurately.

Background: The development of bivalent or multivalent vaccines offers a promising strategy for combating SARS-CoV-2 mutations.

Research design and methods: In this phase 2 trial, conducted from 1 December 2021, to 25 July 2023, 392 unvaccinated adults aged ≥18 years were randomized to receive a primary series of two doses and a booster dose of SCTV01C, a bivalent protein SARS-CoV-2 vaccine.

Results: Geometric mean titers (GMTs) of neutralizing antibodies (nAb) against live Alpha, Beta, Delta, and Omicron showed 85.4-, 100.0-, 32.1-, and 9.8-fold increase from baseline on 28 days, and 49.4-, 55.3-, 5.7-fold increase against live Alpha, Beta, and Omicron on 90 days after primary series. At Day 28 and Day 90 following the booster dose, GMTs of nAb against Beta, BA.2 and BA.5 variants showed 12.1- and 8.8-, 13.8- and 7.1-, 18.7-, and 11.9-fold of increase from baseline, respectively. Reactogenicity was generally mild, with one adverse event of special interest (AESI) and 9 ≥Grade 3 treatment-related adverse events (TRAEs); all recovered within 3 days.

Conclusions: SCTV01C, when administered as both a primary series and a booster vaccination, exhibited encouraging sustained immunogenicity against both antigen-matched and antigen-mismatched variants, with no significant safety concerns.

Clinical trial registration: www.clinicaltrials.gov identifier is NCT05148091.

Introduction: Fifty-eight million people worldwide are chronically infected with hepatitis C virus (HCV) and are at risk of developing cirrhosis and hepatocellular carcinoma (HCC). Direct-acting antivirals are highly effective; however, they are burdened by high costs and the unchanged risk of HCC and reinfection, making prophylactic countermeasures an urgent medical need. HCV high genetic diversity is one of the main obstacles to vaccine development. The protective role of the humoral response directed against the HCV E2 glycoprotein is well established, and broadly neutralizing antibodies play a crucial role in effective viral clearance.

Areas covered: This review explores the HCV targets and the different vaccination approaches, encompassing different expression systems, antigen selection strategies, and delivery methods, focusing on those aimed at eliciting a broad and effective humoral response. Our search criteria included the keywords 'HCV,' 'Hepatitis C,' and 'vaccine' using publicly available databases. Following the screening, 54 papers were selected.

Expert opinion: The investigation of novel vaccine platforms beyond traditional approaches is necessary. While progress has been made in this direction, continued investigations on the HCV virology, immunology, and vaccinology are essential to surmount associated obstacles, heling in the development of an HCV vaccine that can benefit the global public health.

Objectives: The attitudes and perceptions of healthcare consumers (HCCs) are increasingly becoming more relevant in decision-making with healthcare providers and incorporated into healthcare decision-making by national immunization technical advisory groups and health technology assessment agencies. With newer pneumococcal vaccine options available, HCCs' attitudes and perceptions play a key role in gauging potential acceptance. The objective of this study was to assess HCCs' knowledge, attitudes, and perceptions toward pneumococcal vaccines for adults.

Methods: Between March and May 2024, eligible U.S. adult HCCs were invited to participate in an online survey focusing on experiences and attitudes toward vaccines.

Results: Among 141 participating HCCs, average age was 53.1 years. The majority of participants were male (51.1%) and 64.5% identified as White. Most HCCs received at least one vaccine in the past year (81.6%). HCCs most often received vaccines at medical offices and pharmacies. HCCs supported lowering the age-based pneumococcal vaccine recommendation to all adults 50 years and older and were willing to receive a supplemental pneumococcal vaccine dose following completion of the recommended series for additional protection.

Conclusions: These findings indicate that new adult pneumococcal vaccines would be accepted and valued by HCCs if recommended by HCPs.