Expert Review of Vaccines最新文献

Background: Respiratory syncytial virus (RSV) can cause substantial morbidity and mortality in adults aged 50-59 years at increased risk of severe RSV disease due to specific underlying conditions (i.e. '50-59 years at-increased-risk [AIR] population'), and in older adults aged ≥60 years (i.e. '≥60 years population').

Research design and methods: A static multi-cohort Markov model estimated cost-effectiveness of adjuvanted RSVPreF3 vaccination versus no vaccination among the 50-59 years AIR and ≥60 years populations in Japan, over a five-year time horizon from a healthcare payer perspective. Japan-specific RSV epidemiology and healthcare resource utilization parameters were used; vaccine efficacy was derived from the phase 3 AReSVi-006 trial (NCT04886596).

Results: Adjuvanted RSVPreF3 vaccination was cost-effective: in the 50-59 years AIR population, 49,280 RSV cases were prevented and 4333 quality-adjusted life years (QALYs) gained, at an incremental cost-effectiveness ratio (ICER) of Japanese yen (JPY) 2,770,558/QALY; in the ≥60 years population, 2,111,080 RSV cases were prevented and 205,543 QALYs gained, at an ICER of JPY 2,613,241/QALY. Vaccination was more cost-effective when including productivity losses from RSV-ARI. Scenario and sensitivity analyses results were robust.

Conclusions: RSV vaccination may provide substantial health benefits and be a cost-effective intervention to reduce RSV burden in adults in Japan.

Introduction: This systematic review aims to assess determinants of vaccine hesitancy (VH) among healthcare professionals, to identify knowledge gaps and inform targeted training programs.

Research design and methods: A systematic search of PubMed and Scopus was conducted in February 2024. PRISMA criteria were applied, and methodological quality was assessed using a cross-sectional study evaluation tool. Studies addressing HCWs' VH determinants, including knowledge, attitudes, communication, and organizational factors, were included.

Results: Out of 1394 records, 221 articles were included. Reported prevalence of VH among HCWs varied across studies, reflecting differences in professional roles, settings, and vaccines studied. Key determinants included gaps in knowledge, personal beliefs, organizational barriers, and communication skills. The review highlights the importance of evidence-based information, continuing education, and effective communication in addressing VH among HCWs.

Conclusions: Educational and organizational interventions are essential to improve HCWs' knowledge, attitudes, and practices regarding vaccination. Strengthening vaccine education, fostering effective communication, and addressing organizational challenges can reduce hesitancy and support HCWs in promoting vaccination among patients. Future initiatives should consider the diversity of educational settings, professional roles, and training requirements across healthcare systems.

Background: Significant residual burden of invasive pneumococcal disease (IPD) is attributable to Streptococcus pneumoniae serotypes not included in any available vaccines in Germany. This study quantified the burden of invasive pneumococcal disease attributable to PCV21 and PCV20 serotypes among German adults.

Research design and methods: A published state-transition Markov model estimated the lifetime cases, deaths, and direct costs (2023 Euros) of IPD by age (18-49, 50-59, and 60 years and older) and risk group (low-risk, at-risk, and high-risk) in Germany. One-way sensitivity analysis on PCV21 cost was conducted.

Results: Across all age groups, there were 50,462 more IPD cases and 8895 deaths attributable to the serotypes in PCV21 compared to PCV20. The eight unique serotypes to PCV21 accounted for approximately 22% of disease. Higher direct costs were associated with PCV21 serotypes versus PCV20 serotypes (€505,094,685 versus €389,835,550, respectively). Discount rate of costs was the most influential input.

Conclusions: Serotypes in PCV21 compared to PCV20 are associated with greater health and economic burden in Germany, primarily driven by the eight unique serotypes included in PCV21 and no other licensed vaccine. Including PCV21 in the national German vaccination guidelines may substantially reduce IPD-related health and economic burden among adults.

Background: Using adapted COVID-19 vaccines targeting current variants in circulation is necessary for addressing the dynamic evolution of the SARS-CoV-2 virus and protecting against emerging variants.

Research design and methods: Using a previously published, combined Markov-decision tree model adapted for Costa Rica, this study estimated the outcomes of different vaccination strategies with BNT162b2 COVID-19 mRNA vaccine, targeting various age and risk groups. The model used age-specific epidemiology, clinical, cost, and quality-of-life inputs derived from the published literature and national surveillance data. Scenario analyses that implemented variation in COVID-19 incidence and sensitivity analyses were both conducted to assess uncertainty.

Results: Compared to no adapted vaccine, the vaccination strategy in older adults aged ≥65 years and the high-risk population aged 18-64 years was estimated to prevent 3704 symptomatic cases, 3670 outpatient cases, 35 hospitalizations, 102 lost quality-adjusted life-years (QALYs), and one death, translating to total direct and societal cost savings of US$9,465,324 and US$10,569,883, respectively. Expanding vaccination to adults aged ≥60 years and high-risk individuals aged 18-59 years further increased benefits.

Conclusions: Implementing an adapted COVID-19 vaccine strategy for high-risk and older adults in Costa Rica is expected to be cost-saving, with broader age group eligibility yielding even greater benefits.

Introduction: Chronic infections with Trypanosoma cruzi can lead to Chagas disease, with cardiac and/or digestive debilitating manifestations. There has been a renewed interest in vaccine development against this neglected tropical disease in the past decades.

Areas covered: Vaccines ranging from live attenuated to recombinant subunit, nucleic acid, bacterial, viral and algal vectors, targeting various parasite antigens have been tested in mice as preventative and therapeutic vaccine against clinical disease progression as well as in the context of pregnancy to prevent congenital transmission and other adverse birth outcomes. A few of these vaccine candidates have been tested in dogs and non-human primates. Further clinical development faces several challenges associated with slow disease progression and the lack of biomarkers, the diversity of parasite strains, complex host-parasite relationship, among others.

Expert opinion: Pre-clinical studies broadly support the clinical development of a Chagas disease vaccine, particularly for a therapeutic vaccine. Synergy with drug development efforts, which face many of the same challenges, may provide new opportunities to strengthen clinical development and trials of drugs, vaccines and combined therapies.

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.