Expert Review of Vaccines最新文献

Introduction: Dengue incidence has increased over the past few decades. One tetravalent dengue vaccine based on a yellow fever backbone has been approved, but due to increased risk of severe disease in dengue-naïve recipients, its use is limited to individuals with prior dengue exposure.

Areas covered: We summarize the clinical development of TAK-003, a tetravalent dengue vaccine based on a live-attenuated DENV-2 backbone. We discuss vaccine development and preclinical and clinical work leading to a commercially available formulation. TAK-003 is approved in several countries and the WHO-SAGE recommend TAK-003 to be considered for public programs in high transmission areas for individuals aged 6-16 years. Finally, we discuss the potential role of TAK-003 as part of an integrated multimodal strategy for dengue prevention.

Expert opinion: TAK-003 has been assessed in a comprehensive clinical development program; demonstrating sustained efficacy and safety against all four serotypes in baseline seropositive individuals, and against DENV-1 and DENV-2 in seronegative individuals, and has been well tolerated. Effectiveness in a real world setting and safety will be monitored in ongoing and future studies, particularly for DENV-3 and DENV-4, together with the impact of a booster dose. Overall, TAK-003 shows promise as a new tool for dengue prevention.

Introduction: Vaccine hesitancy in Latin America and the Caribbean (LAC) has a complex nature. It is shaped by socio-political, cultural, economic factors, and an influence of the COVID-19 pandemic on increasing hesitancy patterns. While LAC has maintained high vaccination coverage, it has experienced a decline over the past 10-years, further exacerbated by declining vaccine confidence during the pandemic, driven by misinformation, political polarization, and conspiracy theories.

Areas covered: We review the impact of vaccine hesitancy across various stakeholders in LAC, focusing on healthcare professionals, parents, and community leaders, including data from studies conducted in Argentina and Colombia highlighting regional variations in hesitancy patterns. It describes the role of pediatricians in recommending vaccines, particularly in COVID-19 vaccines. The study explores how the rapid spread of misinformation, particularly through social media, exacerbated mistrust, and offers an overview of vaccine hesitancy trends in LAC during/after the pandemic.

Expert opinion: While vaccine acceptance remains high among certain populations, communication strategies are essential to address concerns about vaccine safety. It is imperative to strengthen the relationship between health-providers and the public to mitigate misinformation and improve vaccine uptake. We propose seven strategic approaches for a comprehensive communication aimed at changing the public behavior about vaccines.

Background: China has yet to implement a nationwide two-dose vaccination strategy. This study assesses the real-world effectiveness of varicella vaccination in Guangzhou, where the policy recommends voluntary, self-funded administration of two doses of the live attenuated vaccine, to provide insights for optimizing vaccination strategies.

Research design and methods: Using outbreak data from 2017 to 2022 across preschools, primary, and secondary schools, we employed a three-level matched case-control design (school, grade, and class) and applied conditional logistic regression to estimate the effectiveness of single-dose (VE1) and two-dose (VE2) vaccinations, incremental VE, and the effectiveness of emergency vaccination.

Results: From 2017 to 2022, 1,058 varicella cases were included in the study, with a median age of 9.0 years. The effectiveness of a single-dose vaccine ranged from 45.8% to 46.7%, while the two-dose vaccine showed higher effectiveness (94.5% to 95.8%), with an incremental VE of 89.7% to 92.1%. VE1 decreased over time, whereas VE2 remained relatively high within five years after the booster dose, with the interval between doses having little effect on VE2. Emergency vaccination was effective for the first dose (78.0%-84.5%) and more effective for the second dose (87.2%-91.4%).

Conclusions: Single-dose varicella vaccination provides limited protection, whereas the two-dose regimen enhances effectiveness.

Introduction: Individuals with immunocompromising conditions (e.g. asplenia, complement deficiency, HIV infection) or with high exposure to Neisseria meningitidis (e.g. laboratory workers, those in outbreak settings) have an increased risk of meningococcal disease. Immunization with meningococcal serogroups ACWY (MenACWY) and serogroup B (MenB) vaccines is recommended for high-risk groups in many countries, although definitions of high-risk vary. There are not yet clinical data for the pentavalent meningococcal serogroups ABCWY (MenABCWY) vaccines in high-risk populations.

Areas covered: This review examines studies conducted in high-risk groups with the component vaccines of GSK's MenABCWY vaccine, the 4-component MenB vaccine (4CMenB) and quadrivalent MenACWY CRM₁₉₇-glycoconjugate vaccine (MenACWY-CRM). These component vaccines have been licensed for more than 10 years and are recommended in groups categorized as high risk.

Expert opinion: The component vaccines of GSK's MenABCWY vaccine, 4CMenB and MenACWY-CRM, have demonstrated immunogenicity and safety in high-risk groups, including with concomitant or sequential vaccine administration. As expected, immunogenicity was reduced in patients with complement deficiencies, particularly those receiving eculizumab. Further data are required on meningococcal vaccination in high-risk groups for the future refinement of national and regional recommendations and to support proactive approaches to improve vaccine uptake in high-risk groups.

Background: Risk of herpes zoster (HZ) increases with age (notably at ≥50 years), with greater risk also apparent in immunocompromised populations. The use of the recombinant zoster vaccine (RZV) in adults aged ≥50 years is established in Canada. However, while licensed RZV use was expanded in 2021 to include individuals ≥18 years of age who are or will be at increased risk of HZ due to immunodeficiency or immunosuppression caused by known disease or therapy, there remains some uncertainty for clinicians regarding which patients should be offered vaccination.

Research design and methods: To assist decision-making, a Canadian multidisciplinary panel was convened to develop guidance on the use of RZV in at-risk adults aged ≥18 years through a consensus approach, defined as ≥75% of the experts rating their agreement.

Results: The panel concluded that RZV should be offered to all at-risk individuals aged ≥18 years who are or will be at increased risk of HZ due to disease or therapy, in line with the licensed indication. This includes those with chronic medical conditions at greater risk of HZ (e.g. COPD, diabetes). Decisions should be individualized based upon patient assessment and shared clinical decision-making. Where possible, the two-dose vaccine series should be given at the earliest opportunity.

Conclusions: Findings from this expert consensus provide guidance on the use of RZV in individuals ≥18 years at increased risk of HZ. Our views complement updated national recommendations for immunocompromised patients issued in May 2025.

Background: As the COVID-19 pandemic transitions into its fourth year, understanding the dynamics of immunity is critical for implementing effective public health measures. This study examines vaccine-induced, natural, and hybrid immunity to SARS-CoV-2 in Hong Kong, focusing on their protective effectiveness and waning characteristics against infection during the Omicron BA.1/2 dominant period.

Research design and methods: We conducted a territory-wide retrospective cohort study using vaccination and infection records from the Hong Kong Department of Health. The analysis included over 6.5 million adults, applying the Andersen-Gill model to estimate protective effectiveness while addressing selection bias through inverse probability weighting.

Results: Vaccine-induced immunity peaked one month after the first dose but waned rapidly, while boosters significantly prolonged protection. Infection-induced immunity showed higher initial effectiveness but declined faster than vaccine-induced immunity. Hybrid immunity provided the most durable protection. mRNA vaccines (Comirnaty) demonstrated greater effectiveness and slower waning compared to inactivated vaccines (CoronaVac).

Conclusions: Hybrid immunity represents the most effective strategy for sustained protection against SARS-CoV-2. Public health policies should emphasize booster campaigns and hybrid immunity pathways to enhance population-level immunity and guide future COVID-19 management in Hong Kong.

Background: In the context of China's rapidly aging population and persistently low pneumococcal vaccine coverage, this study applied the Behavioral and Social Drivers (BeSD) framework to investigate the willingness and determinants of pneumococcal vaccination among adults aged 60 years and older in Chongqing.

Research design and methods: We designed a cross-sectional survey targeting the community population and collected data on willingness toward pneumonia vaccination and associated demographic factors through questionnaires.

Results: A total of 1,617 valid questionnaires were collected, 37.7% expressed willingness to receive pneumococcal vaccines. Higher vaccination willingness was associated with living in urban areas, having urban employee basic medical insurance, having an average monthly household income per capita below 2,000 CNY, being aware of pneumococcal vaccines, and showing interest in receiving vaccination information. Concerning the BeSD framework, concern over worsening health condition emerged as the primary driver, whereas perceived high vaccine costs and lack of awareness about vaccine were identified as major reasons for hesitancy.

Conclusions: This study provides that future strategies should focus on addressing psychological determinants within old adults, alongside extensive promotion of knowledge regarding pneumonia vaccination, as well as exploring the impact of financial incentives on vaccination programs and payment strategies to enhance vaccination coverage.

Introduction: Circulating influenza strains, vaccine effectiveness (VE), and vaccine recommendations vary over time. A systematic literature review (SLR), random effects meta-analysis (REMA), and network meta-analysis (NMA) estimated absolute VE (aVE) and relative VE (rVE) of LAIV and IIV in children/adolescents from initial LAIV approval in 2003.

Methods: Northern Hemisphere studies (2003-2023) with children ≤19 yrs were included. A modified Newcastle-Ottawa Scale assessed risk-of-bias. REMA estimated aVE and three-node NMA (LAIV-IIV-unvaccinated) estimated rVE over three periods: 2003-04 to 2008-09 (pre-2009 A(H1N1) pandemic); 2010-11 to 2016-17 (post-2009 pandemic); 2017-18 to 2022-23 (post-LAIV strain-selection optimization).

Results: One hundred and nine studies included. aVE of LAIV and IIV against any influenza was similar (~50%) in each period. Effectiveness of LAIV vs. IIV against influenza types/subtypes was comparable except (1) greater effectiveness with IIV for A(H1N1) in 2010-11 to 2016-17 (rVE -46% [95% CI: -57, -33]); (2) greater effectiveness with LAIV for influenza B in 2017-18 to 2022-23 (rVE 196% [95% CI: 73, 406]). In 2017-18 to 2022-23, effectiveness of LAIV and IIV against A(H1N1) was similar (rVE 10% [95% CI: -35, 87]).

Conclusions: LAIV and IIV have demonstrated comparable effectiveness against any influenza in children.

Introduction: Pertussis vaccination in pregnancy is a safe and highly effective strategy to protect young infants against severe pertussis, but cases continue to occur. In November 2023, the authors of this paper met to discuss difficulties faced by pertussis vaccination programs in pregnant women in Europe, and the need and potential for new vaccines.

Areas covered: We summarize current pertussis epidemiology, the status of pertussis vaccination in pregnancy in Europe, followed by a summary of the meeting on benefits of pertussis-only vaccines and pertussis vaccines with improved immunogenicity, including a review of available vaccines.

Expert opinion: Ongoing surveillance and registers documenting vaccine uptake in pregnant women are important to monitor changes in pertussis epidemiology and estimated effectiveness of maternal pertussis vaccination programs in individual countries. While current programs have been effective, Tdap or Tdap-IPV combined vaccines are not the ideal choice but are the only vaccines available for pertussis immunization in pregnancy in Europe. Pertussis-only vaccine would avoid exposing women to unnecessary tetanus and diphtheria boosters in every pregnancy. Recombinant pertussis vaccines with higher immunogenicity could prolong passive immune protection against pertussis in young infants.

Introduction: Nipah virus is a high-consequence pathogen that causes sporadic outbreaks with high mortality, and there are currently no vaccines or therapeutics available for Nipah. Vaccine development against Nipah faces challenges due to its current epidemiology with limited outbreak sizes, which impedes the feasibility of conducting vaccine efficacy trials focused on disease endpoints.

Areas covered: We review the progress of Nipah vaccine candidates in human clinical trials and highlight the challenges in evaluating the vaccine efficacy due to the sporadic nature of Nipah outbreaks, given the epidemic potential of Nipah virus and its implications for pandemic preparedness. We examine the alternative regulatory pathways, including the US FDA's Animal Rule and EMA's conditional marketing authorization, which permit vaccine approval based on surrogate markers rather than efficacy data from the large-scale Phase-3 efficacy trials. The need for standardized immune surrogate markers is emphasized, alongside calls for international collaboration to develop such endpoints and manage stockpile strategies.

Expert opinion: We recommend alignment among vaccine developers, regulators, and global health stakeholders to incentivize Nipah vaccine development and approval through alternative regulatory pathways, as well as ensuring epidemic preparedness via strategic vaccine stockpiling and response through targeted deployment strategies.