Publications by authors named "Jean-Louis Excler"

Clinical trials are the most rigorous scientific and regulated method to investigate the safety and efficacy of vaccines or drugs in pre-licensure stage. Clinical trial design and implementation are complex, time-consuming and involves close engagement with country's regulatory authority, clinical trial sites, investigators, and the healthcare system. Over the past few decades, a significant number of clinical trials have been conducted in low- and middle-income countries (LMICs), particularly in resource-limited settings.

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Observational studies on COVID-19 vaccine effectiveness (VE) have provided critical real-world data, informing public health policy globally. These studies, primarily using pre-existing data sources, have been indispensable in assessing VE across diverse populations and developing sustainable vaccination strategies. Cohort design is frequently employed in VE research.

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Article Synopsis
  • A study was conducted in Thailand to compare the effectiveness of single-dose versus two-dose regimens of the HPV vaccine among 13-14 year old schoolgirls.
  • The researchers assessed HPV prevalence among unvaccinated schoolgirls and compared it to vaccinated girls over a period of four years.
  • Results showed a significant reduction in HPV prevalence among vaccinated girls, highlighting the potential effectiveness of a single-dose regimen.
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Introduction: The COVID-19 pandemic catalyzed unprecedented vaccine innovation, revealing critical shortcomings in achieving equitable vaccine access and underscoring the need for a focused review of the lessons learned to inform future pandemic preparedness, with emphasis on vaccine delivery, equity, and challenges in LMICs.

Areas Covered: We critically analyzed the pandemic vaccine development and distribution journey and the operational mechanisms that facilitated these achievements. For this purpose, we primarily searched pandemic vaccine stakeholder websites, reports, and publications.

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Non-typhoidal (NTS) infection and invasive non-typhoidal (iNTS) infection cause a significant global health and economic burden. This systematic review aims to investigate the reported economic burden of NTS and iNTS infection, identify research gaps, and suggest future research directions. Data from PubMed and Embase databases up to April 2022 were reviewed, and articles were screened based on predefined criteria.

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Background: Inactivated whole-virus vaccination elicits immune responses to both SARS-CoV-2 nucleocapsid (N) and spike (S) proteins, like natural infections. A heterologous Ad26.COV2.

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For vaccine development and adoption decisions, the 'Full Value of Vaccine Assessment' (FVVA) framework has been proposed by the WHO to expand the range of evidence available to support the prioritization of candidate vaccines for investment and eventual uptake by low- and middle-income countries. Recent applications of the FVVA framework have already shown benefits. Building on the success of these applications, we see important new opportunities to maximize the future utility of FVVAs to country and global stakeholders and provide a proof-of-concept for analyses in other areas of disease control and prevention.

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The spectrum of diseases caused by Streptococcus pyogenes (Strep A) ranges from superficial to serious life-threatening invasive infections. We conducted a scoping review of published articles between 1980 and 2021 to synthesize evidence of state transitions across the Strep A disease spectrum. We identified 175 articles reporting 262 distinct observations of Strep A disease state transitions.

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We compared high-risk human papillomavirus (HPV) detection on first-stream urine from self-sampled collection device (Colli-Pee) and same-day clinician-collected cervical swab in 240 women. Testing with automated cobas 4800 system showed 96.7 % concordance (198 concordant-negative, 34 concordant-positive, Cohen's kappa=0.

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Article Synopsis
  • Climate change poses a serious threat to public health, potentially leading to an estimated 250,000 additional deaths annually by 2030, especially in resource-limited countries.
  • The relationship between climate change and the spread of infectious diseases is increasing, highlighting the urgency for effective public health interventions, including vaccines.
  • The review emphasizes the need for enhanced research and funding to develop vaccines that can help mitigate the health impacts of climate change, particularly on water-related, vector-borne, and airborne diseases.
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Group A Streptococcus causes a wide range of diseases from relatively mild infections including pharyngitis to more severe illnesses such as invasive diseases and rheumatic heart disease (RHD). Our aim is to estimate the cost-effectiveness of a hypothetical Strep A vaccine on multiple disease manifestations at the global-level. Cost-effectiveness analyses were carried out by building on the potential epidemiological impact of vaccines that align with the WHO's Preferred Product Characteristics for Strep A vaccines.

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Background: Leptospirosis, a prevalent zoonotic disease with One Health priority and a disease of poverty, lacks global economic burden estimates. This study aims to determine the global, regional, and country-level cost of leptospirosis due to loss of productivity.

Methodology/principal Findings: The cost of leptospirosis due to loss of productivity (referred to as productivity cost hereafter) was estimated by converting the disability-adjusted life years (DALYs) lost due to leptospirosis to a monetary value using the per capita gross domestic product (GDP).

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Investment in Strep A vaccine R&D is disproportionately low relative to the large burden of Strep A diseases globally. This study presents a novel Strep A vaccine global demand and financial forecast model with estimates of potential global demand and associated revenue and profits for a hypothetical Strep A vaccine as well as a net present value (NPV) analysis of return on capital investments required to develop the vaccine. A positive NPV was calculated for a variety of developer scenarios and target populations, including the global rollout of the vaccine in private and public markets by a multinational pharmaceutical corporation and a staged rollout by a developing country vaccine manufacturer for both infant and child populations.

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Background: The inactivated COVID-19 whole-virus vaccine BBIBP-CorV has been extensively used worldwide. Heterologous boosting after primary vaccination can induce higher immune responses against SARS-CoV-2 than homologous boosting. The safety and immunogenicity after 28 days of a single Ad26.

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Although significant progress has been made in achieving goals for COVID-19 vaccine access, the quest for equity and justice remains an unfinished agenda. Vaccine nationalism has prompted calls for new approaches to achieve equitable access and justice not only for vaccines but also for vaccination. This includes ensuring country and community participation in global discussions and that local needs to strengthen health systems, address issues related to social determinants of health, build trust and leverage acceptance to vaccines, are addressed.

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Through the experiences gained by accelerating new vaccines for both Ebola virus infection and COVID-19 in a public health emergency, vaccine development has benefited from a 'multiple shots on goal' approach to new vaccine targets. This approach embraces simultaneous development of candidates with differing technologies, including, when feasible, vesicular stomatitis virus or adenovirus vectors, messenger RNA (mRNA), whole inactivated virus, nanoparticle and recombinant protein technologies, which led to multiple effective COVID-19 vaccines. The challenge of COVID-19 vaccine inequity, as COVID-19 spread globally, created a situation where cutting-edge mRNA technologies were preferentially supplied by multinational pharmaceutical companies to high-income countries while low and middle-income countries (LMICs) were pushed to the back of the queue and relied more heavily on adenoviral vector, inactivated virus and recombinant protein vaccines.

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The COVID-19 pandemic triggered a sense of vulnerability and urgency that led to concerted actions by governments, funders, regulators and industry to overcome traditional challenges for the development of vaccine candidates and to reach authorisation. Unprecedented financial investments, massive demand, accelerated clinical development and regulatory reviews were among the key factors that contributed to accelerating the development and approval of COVID-19 vaccines. The rapid development of COVID-19 vaccines benefited of previous scientific innovations such as mRNA and recombinant vectors and proteins.

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Article Synopsis
  • The RV144 HIV-1 vaccine gave a 31% efficacy after three years but showed a decline in immune protection; new strategies for enhancing immunity are needed.
  • The RV305 trial tested booster shots on RV144 participants years later and found improved immune responses, especially with the ALVAC vaccine boost.
  • The study revealed that while overall antibody levels increased, certain antibodies linked to higher HIV-1 risk also rose, highlighting the need for careful evaluation of booster effects on antibody quality.
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Article Synopsis
  • Streptococcus pyogenes (Strep A) infections are a significant global health issue, often overlooked, leading to both acute and chronic diseases.* -
  • The Strep A Vaccine Global Consortium (SAVAC) aims to fast-track the development of safe and effective vaccines for Strep A, prioritizing the safety of recipients.* -
  • Though no safety concerns were noted in recent early-phase clinical trials, there is a need for enhanced safety assessments specifically for pediatric trials, large efficacy studies, and ongoing monitoring after vaccines are released.*
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Considering the lack of existing evidence on economic burden for diseases caused by group A Streptococcus, we estimated the economic burden per episode for selected diseases. Each cost component of direct medical costs (DMCs), direct non-medical costs (DNMCs), and indirect costs (ICs) was separately extrapolated and aggregated to estimate the economic burden per episode by income group as classified by the World Bank. Adjustment factors for DMC and DNMC were generated to overcome related data insufficiencies.

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Article Synopsis
  • The study aimed to find out how common high-risk (HR) and vaccine-type HPV infections are among Thai schoolgirls not involved in the national HPV immunization program.
  • Cross-sectional surveys were conducted on grade 10 and grade 12 girls, who provided urine samples that were tested for HPV, showing different prevalence rates for various HPV types.
  • The results highlighted a significant presence of HR HPV infections among unvaccinated girls, with particular types like HPV16 being the most prevalent.
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Recent efforts have re-invigorated the Streptococcus pyogenes (Group A Streptococcus) vaccine development field, though scientific, regulatory and commercial barriers persist, and the vaccine pipeline remains sparse. There is an ongoing need to accelerate all aspects of development to address the large global burden of disease caused by the pathogen. Building on over 100 years of S.

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Understanding immunity in humans to Group A Streptococcus (Strep A) is critical for the development of successful vaccines to prevent the morbidity and mortality attributed to Strep A infections. Despite decades of effort, no licensed vaccine against Strep A exists and immune correlates of protection are lacking; a major impediment to vaccine development. In the absence of a vaccine, we can take cues from the development of natural immunity to Strep A in humans to identify immune correlates of protection.

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Inactivated viral vaccines have long been used in humans for diseases of global health threat (e.g., poliomyelitis and pandemic and seasonal influenza) and the technology of inactivation has more recently been used for emerging diseases such as West Nile, Chikungunya, Ross River, SARS and especially for COVID-19.

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Human papillomavirus (HPV) is a common infection principally spread through sexual activity. Most HPV infections are asymptomatic and resolve spontaneously. However, persistent infection may progress to cervical cancer.

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