Expert Review of Vaccines最新文献

Introduction: Rotavirus vaccines may provide indirect protection by reducing transmission in the population and thus reducing disease burden.

Methods: This systematic review summarizes estimates of indirect protection from rotavirus vaccines and the methods used to obtain these estimates.

Results: We identified 71 studies published between 2009 and 2022 that provided 399 estimates of indirect protection from rotavirus vaccine. Most estimates (73%) evaluated hospitalizations due to rotavirus gastroenteritis as the outcome and unvaccinated children <5 years old as the agegroup (64%), but there was considerable variability in methods to evaluate indirect protection. For hospitalizations due to rotavirus gastroenteritis among unvaccinated children <5 years old, the median incidence rate ratio was 0.60 (IQR: 0.40-0.87, n = 110 estimates), the median relative percent change in percent positivity was 25% (IQR: 13-44%, n = 49 estimates), and the median relative percent change in absolute number of rotavirus positive tests or rotavirus-specific International Classification of Diseases codes was 42% (IQR: 16-66%, n = 40 estimates).

Conclusions: These findings broadly suggest rotavirus vaccines provide some indirect protection. There is a need to standardize measurement of indirect rotavirus vaccine protection, particularly using consistent outcomes and metrics, and stratifying results by standardized age groups and years since vaccine introduction.

Introduction: Dengue disease represents a large and growing global threat to public health, accounting for a significant burden to health systems of endemic countries. The World Health Organization's (WHO) Strategic Advisory Group of Experts (SAGE) and the European Medicines Agency (EMA) currently recommend the use of TAK-003 dengue vaccine in high dengue burden and transmission settings for countries considering vaccination as part of their integrated management strategy for prevention and control of Dengue.

Areas covered: This paper describes the main conclusions of a workshop held by the Arbovirus Committee of the Latin American Society of Pediatric Infectious Diseases (SLIPE) in November 2023, to generate consensus recommendations on the introduction of this new vaccine in the region. Considerations were made regarding the molecular epidemiology of dengue infection in the Americas and the need for more precise phylogenetic classification and correlation with clinical outcome and disease severity.

Expert opinion: Introduction of dengue vaccine should be considered as an strategy for health entities in the region, with participation of social sectors, scientific societies, and ministries of health that could be able to create a successful vaccination program.

Background: Traditional vaccine development, often a lengthy and costly process of three separated phases. However, the swift development of COVID-19 vaccines highlighted the critical importance of accelerating the approval of vaccines. This article showcases a seamless phase 2/3 trial design to expedite the development process, particularly for multi-valent vaccines.

Research design and methods: This study utilizes simulation to compare the performance of seamless phase 2/3 design with that of conventional trial design, specifically by re-envisioning a 9-valent HPV vaccine trial. Across three cases, several key performance metrics are evaluated: overall power, type I error rate, average sample size, trial duration, the percentage of early stop, and the accuracy of dose selection.

Results: On average, when the experimental vaccine was assumed to be effective, the seamless design that performed interim analyses based solely on efficacy saved 555.73 subjects, shortened trials by 10.29 months, and increased power by 3.70%. When the experimental vaccine was less effective than control, it saved an average of 887.73 subjects while maintaining the type I error rate below 0.025.

Conclusion: The seamless design proves to be a compelling strategy for vaccine development, given its versatility in early stopping, re-estimating sample sizes, and shortening trial durations.

Background: There is a lack of synthesis of literature to determine hepatitis B vaccine (HepB) strategies for hepatitis B virus (HBV) supported by quality evidence. We aimed to explore the efficacy and safety of HepB strategies among people with different characteristics.

Research design and methods: PubMed, Cochrane Library, Embase, and Web of Science were searched for meta-analyses comparing the efficacy and safety of HepB up to July 2023.

Results: Twenty-one meta-analyses comparing 83 associations were included, with 16 high quality, 4 moderate, and 1 low quality assessed by AMSTAR 2. Highly suggestive evidence supports HepB booster and HepB with 1018 adjuvant (HBsAg-1018) for improved seroprotection, and targeted and universal HepB vaccination reduced HBV infection Suggestive evidence indicated that targeted vaccination decreased the rate of hepatitis B surface antibody positivity and booster doses increased seroprotection in people aged 10-20. Weak evidence suggests potential local/systemic reaction risk with nucleotide analogs or HBsAg-1018. Convincing evidence shows HLA-DPB1*04:01 and DPB1*04:02 increased, while DPB1*05:01 decreased, hepatitis B antibody response. Obesity may reduce HepB seroprotection, as highly suggested.

Conclusion: Targeted vaccination could effectively reduce HBV infection, and adjuvant and booster vaccinations enhance seroprotection without significant reaction. Factors such as obesity and genetic polymorphisms may affect the efficacy.

Introduction: Transmissible vaccines offer a novel approach to suppressing viruses in wildlife populations, with possible applications against viruses that infect humans as zoonoses - Lassa, Ebola, rabies. To ensure safety, current designs propose a recombinant vector platform in which the vector is isolated from the target wildlife population. Because using an endemic vector creates the potential for preexisting immunity to block vaccine transmission, these designs focus on vector viruses capable of superinfection, spreading throughout the host population following vaccination of few individuals.

Areas covered: We present original theoretical arguments that, regardless of its R₀ value, a recombinant vaccine using a superinfecting vector is not expected to expand its active infection coverage when released into a wildlife population that already carries the vector. However, if superinfection occurs at a high rate such that individuals are repeatedly infected throughout their lives, the immunity footprint in the population can be high despite a low incidence of active vaccine infections. Yet we provide reasons that the above expectation is optimistic.

Expert opinion: High vaccine coverage will typically require repeated releases or release into a population lacking the vector, but careful attention to vector choice and vaccine engineering should also help improve transmissible vaccine utility.

Introduction: The global measles incidence has decreased from 145 to 49 cases per 1 million population from 2000 to 2018, but evaluating the economic benefits of a second measles-containing vaccine (MCV2) is crucial. This study reviewed the evidence and quality of economic evaluation studies to guide MCV2 introduction.

Methods: The systematic review of model-based economic evaluation studies was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The search yielded 2231 articles, with 876 duplicates removed and 1355 articles screened, with nine studies included for final analysis.

Results: Six studies reported a positive benefit-cost ratio with one resulting in net savings of $11.6 billion, and two studies estimated a 2-dose MMR vaccination program would save $119.24 to prevent one measles case, and a second dose could prevent 9,200 cases at 18 months, saving $548.19 per case. The most sensitive variables were the discount rate and vaccination administration cost.

Conclusions: Two MCV doses or a second opportunity with an additional dose of MCV were highly cost-beneficial and resulted in substantial cost savings compared to a single routine vaccine. But further research using high-quality model-based health economic evaluation studies of MCV2 should be made available to decision-makers.

Prospero registration: CRD42020200669.

Introduction: Persistent infections with the human papilloma viruses, HPV16 and HPV18, are associated with multiple cancers. Although prophylactic vaccines that induce HPV-neutralizing antibodies are effective against primary infections, they have no effect on HPV-mediated malignancies against which there is no approved immuno-therapy. Active research is ongoing in the immunotherapy of these cancers.

Areas covered: In this review, we compared the preclinical efficacy of vaccine platforms used to treat HPV-induced tumors in the standard model of mice grafted with TC-1 cells, which express the HPV16 E6 and E7 oncoproteins. We searched for the key words, 'HPV,' 'vaccine,' 'therapy,' 'E7,' 'tumor,' 'T cells', and 'mice' for the period from 2005 to 2023 in PubMed and found 330 publications. Among them, we selected the most relevant to extract preclinical antitumor results to enable cross-sectional comparison of their efficacy.

Expert opinion section: We compared these studies for HPV antigen design, immunization regimen, immunogenicity, and antitumor effect, considering their drawbacks and advantages. Among all strategies used in murine models, certain adjuvanted proteins and viral vectors showed the strongest antitumor effects, with the use of lentiviral vectors being the only approach to result in complete tumor eradication in 100% of experimental individuals while providing the longest-lasting memory.

Background: The question of whether influenza vaccine effectiveness (VE) wanes over the winter season is still open and some contradictory findings have been reported. This study investigated the possible decline in protection provided by the available influenza vaccines.

Research design and methods: An individual-level pooled analysis of six test-negative case-control studies conducted in Italy between the 2018/2019 and 2022/2023 seasons was performed. Multivariable logistic regression analyses were performed to estimate weekly change in the odds of testing positive for influenza 14 days after vaccination.

Results: Of 6490 patients included, 1633 tested positive for influenza. Each week that had elapsed since vaccination was associated with an increase in the odds of testing positive for any influenza (4.9%; 95% CI: 2.0-8.0%) and for A(H3N2) (6.5%; 95% CI: 2.9-10.3%). This decline in VE was, however, significant only in children and older adults. A similar increase in the odds of testing positive was seen when the dataset was restricted to vaccinees only. Conversely, VE waning was less evident for A(H1N1)pdm09 or B strains.

Conclusions: Significant waning of VE, especially against influenza A(H3N2), may be one of the factors associated with suboptimal end-of-season VE. Next-generation vaccines should provide more durable protection against A(H3N2).

Introduction: Different COVID-19 vaccines are being utilized as boosters. This systematic review and meta-analysis aims to evaluate the reactogenicity of COVID-19 vaccines given as booster doses, according to vaccine type, dose, timing, participant characteristics and primary immunization regimen received.

Methods: Four databases (MEDLINE, Embase, Web of Science and CENTRAL) were searched for randomized controlled trials between 1 January 2020 and 1 January 2023 according to predetermined criteria.

Results: Twenty-eight studies describing 19 vaccines of four different types (viral vector, inactivated, mRNA and protein sub-unit) were identified. BNT162b2 vaccine (Pfizer-BioNTech) was selected as the control as it was most often compared with other vaccines. Fever, fatigue, headache, injection-site pain, redness, and swelling were the most frequently reported solicited events. mRNA vaccines were the most reactogenic, followed by viral vector vaccines and protein sub-unit vaccines, while inactivated vaccines were the least reactogenic. Full-dose vaccines were more reactogenic than half-dose vaccines. Heterologous BNT162b2 boosters were more reactogenic than boosters with the same vaccine used for primary immunization.

Conclusions: COVID-19 vaccine booster schedules have distinct reactogenicity profiles, dependent on dose and vaccine type, which may allow targeted recommendations and provide choice for specific populations. Greater standardization of adverse event reporting will aid future studies.

Background: As the societal value of vaccines is increasingly recognized, there is a need to examine methodological approaches that could be used to integrate these various benefits in the economic evaluation of a vaccine.

Research design and methods: A literature review and two expert panel meetings explored methodologies to value herd immunity, health spillover effects (beyond herd immunity), impact on antimicrobial resistance, productivity, and equity implications of vaccines.

Results: The consideration of broader benefits of vaccines in economic evaluation is complicated and necessitates technical expertise. Whereas methodologies to account for herd immunity and work productivity are relatively well established, approaches to investigate equity implications are developing and less frequently applied. Modeling the potential impact on antimicrobial resistance not only depends on the multi-faceted causal relationship between vaccination and resistance but also on data availability.

Conclusions: Different methods are available to value the broad impact of vaccines, and it is important that analysts are aware of their strengths and limitations and justify their choice of method. In the future, we expect that an increasing number of economic evaluations will consider the broader benefits of vaccines as part of their base-case analysis or in sensitivity analyses.