Expert Review of Vaccines最新文献

Introduction: Lyme disease is caused by the tick-borne spirochete pathogen Borrelia burgdorferi sensu lato (s.l.). Outer surface protein A (OspA) is expressed by B. burgdorferi s.l. while in the tick and antibodies against OspA introduced into the tick with the bloodmeal can prevent transmission. OspA-based vaccines have been validated in people, however, there are currently no available human Lyme disease vaccines. Hexavalent OspA vaccine VLA15 is designed to cover the dominant B. burgdorferi s.l. genospecies causing disease in North America and Europe and is currently the most advanced candidate human Lyme disease vaccine in clinical development.

Areas covered: A historical retrospective of the discovery and evolving burden of Lyme disease is covered, as well as relevant aspects of the vector biology, preclinical research underpinning development of VLA15, and its clinical development to date.

Expert opinion: Lyme disease has expanded over the past two decades in both incidence and geographic footprint and is anticipated to continue to increase in the future due to changing climate and human encroachment into wildlife areas. VLA15 is currently in the last stage of clinical development, and if found to be safe and efficacious, may offer an important prophylactic modality for prevention of Lyme disease.

Introduction: Prophylactic human papillomavirus vaccines have been in use in populations worldwide for nearly 20 years. Much has been learnt in relation to their effectiveness, safety, and how best to effectively implement them in populations to prevent cancer and other HPV-related diseases. Global challenges such as limited supply and the mismatch between those who can afford them and those with the greatest disease burden from cervical cancer have prevented optimal usage to date.

Areas covered: Here we identified recent papers and focus upon the accumulated evidence regarding HPV vaccine: i) effectiveness in preventing cancer and precancerous lesions, ii) safety in population usage, iii) trial evidence supporting registration of four newer vaccines, iv) progress in country-level introductions and coverage, and v) lessons learned in effective implementation.

Expert opinion: Reasons for optimism are many, with vast cumulative knowledge on impact, safety and implementation and accelerating HPV vaccine introductions, simplification of delivery and reduced costs through single dose approaches and supply constraints easing. However, considerable challenges remain in achieving and maintaining high and equitable global coverage, given the uncertainty in funding, risk to ongoing prioritization of health equity and to vaccine confidence in the current global public health environment.

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.

Introduction: Pneumococcal disease leads to high morbidity and mortality, particularly in older adults and immunocompromised individuals. Many pneumococcal conjugated vaccines (PCVs) have become available. However, the immunogenicity, efficacy, and effectiveness data of these vaccines in older adults and immunocompromised individuals are limited.

Areas covered: This review aims to critically examine the immune responses, immune correlations, efficacy, real-world effectiveness, and cost-effectiveness of pneumococcal conjugated vaccines (PCVs) in older adults and immunocompromised individuals.

Expert opinion: A single dose of 20-valent or 21-valent PCV is recommended for older adults and immunocompromised individuals. Immune correlates of protection vary by serotype and race. An IgG level of 0.35 µg/mL is associated with protection, though this threshold is serotype-dependent. Opsonophagocytic assays, with a threshold of 1:8, remain the most reliable functional correlate of protection against invasive pneumococcal disease. Standardized immunological assays are essential for evaluating immune responses. High-valent PCVs have shown noninferior immunogenicity compared to PCV13, though geometric mean fold rises (GMFRs) for shared serotypes are slightly lower. Real-world effectiveness data are still needed, particularly in regions with differing serotype prevalence. Serotype surveillance is crucial when introducing PCV programs. Due to the high cost of higher-valent PCVs, many countries continue using PCV13 or PCV15 followed by PPSV23 for high-risk groups.

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 is attributable to Streptococcus pneumoniae serotypes not included in any available vaccines in Germany. This study quantified the burden of invasive pneumococcal disease (IPD) attributable to V116 and PCV20 serotypes among German adults.

Research design and methods: A 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 V116 cost was conducted.

Results: Across all age groups, there were 50,462 more IPD cases and 8895 deaths attributable to the serotypes in V116 compared to PCV20. The eight unique serotypes to V116, accounted for approximately 22% of V116 serotypes. Higher direct costs were associated with V116 serotypes versus PCV20 serotypes (€505,094,685 versus €389,835,550, respectively). Discount rate of costs was the most influential input.

Conclusions: Serotypes in V116 compared to PCV20 are associated with greater health and economic burden in Germany, primarily driven by the eight unique serotypes included in V116 and no other licensed vaccine. Including V116 in the national German vaccination guidelines may substantially reduce IPD-related health and economic burden among adults.

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.