Gaps in vaccine clinical trials in Africa: A mixed scoping review and bibliometric analysis before, during, and post- COVID-19 pandemic

ABSTRACT

Africa’s participation in vaccine trials has historically been limited, but the COVID-19 pandemic highlighted the need for greater involvement. This study explores vaccine clinical development in Africa, emphasizing its importance for global health security. Using a scoping review and bibliometric analysis, we examined 662 vaccine trials conducted before, during, and after the pandemic. The analysis revealed a significant increase in vaccine trials after 2018 and particularly following the end of the COVID-19 pandemic in May 2023. Most trials focused on viral infections and were single-country studies. Pharmaceutical company sponsors funded most of the earlier trials, with increased government and academic involvement post-2020. Despite progress, challenges remain in the geographic distribution of trials, the number of government-supported studies, and the diversity of conditions studied. Addressing these gaps is crucial to bolstering Africa’s role in global vaccine development.

Introduction

Vaccine development has long been a critical component of global health security, particularly in the face of the threat posed by emerging and reemerging infectious diseases.¹ The African region bears the greatest global burden of public health emergencies, with more than 100 major events reported each year. Due to its diverse population, high burden of infectious diseases, and fragile healthcare systems, Africa has become a pivotal site for therapeutic and vaccine trials in infectious diseases. Further, the advent of the COVID-19 pandemic has dramatically underscored the need to comprehensively understand the landscape of vaccine research and development within the African context² and address access and equity. However, despite this urgent need, few in-depth analyses have scrutinized the characteristics of vaccine trials in Africa, particularly in terms of their geographical distribution, regional focus, sources of funding, and outcomes.

Historically, Africa has been underrepresented in global vaccine clinical development programs, despite its high burden of infectious diseases. This disparity raises questions about the inclusiveness and relevance of global health initiatives on the continent.^3,4 A thorough understanding of the scope and nature of vaccine trials conducted in Africa is necessary to inform future policy and investment directions and ensure that the continent is involved in and that its vaccine trial activities align with local, continental and global health priorities.⁵

The COVID-19 pandemic disrupted routine immunization programs across Africa, leading to declines in vaccine coverage for diseases such as measles, polio, and diphtheria. While catch-up immunization efforts have helped mitigate some of these gaps, persistent vaccine misinformation and hesitancy continue to hinder full recovery, exacerbating disparities in coverage and increasing the risk of future outbreaks.⁶ Understanding these disruptions is crucial for developing resilient vaccination systems that can withstand future crises and exploring the potential to repurpose existing vaccines to combat emerging infectious threats such as mpox. Robust and agile vaccine research and development programs are needed to respond rapidly to new threats.^7,8

Additionally, an examination of funding for vaccine trials in Africa can enhance our understanding of the roles played by diverse stakeholders, including private companies, public governments, and private-public partnerships.⁹ By analyzing how funding is distributed, this study aims to identify critical investment gaps and opportunities. The aim of this study is to conduct a thorough bibliometric and scoping review of vaccine trials conducted in Africa before, during and after the COVID-19 pandemic, provide a comprehensive overview of the state of vaccine clinical research in Africa today, and discuss current gaps and future directions in the field.

Methods

Protocol

The study background, rationale, and methods were specified in advance. The study followed the Arksey and O’Malley framework for scoping reviews, which consists of five stages: identifying the research question, identifying relevant studies, selecting studies, charting the data, and collating, summarizing, and reporting the results.¹⁰ The bibliometric component of the study was integrated within the scoping review to provide a comprehensive perspective of vaccine trials in Africa.

The research questions for this mixed review were:

1. Vaccine and Disease Target Focus: Which vaccine types and diseases have been prioritized in Africa’s research efforts?

2. Vaccine Trial Dynamics: What are the patterns in Africa’s vaccine trials concerning early versus late-stage development, pharmaceutical versus nonpharmaceutical?

Eligibility criteria

We included both published and registry clinical data on vaccine trials conducted in Africa from 2010 (the decade before the COVID-19 pandemic) to 2024. The analysis included trials targeting diverse populations and various vaccine technologies. It focused on the safety, effectiveness, and operational aspects of these trials. Comparisons were drawn between trials based on their design, funding sources, and the time of execution (before or after the COVID-19 pandemic).

Information sources

Two data sources were used in this research. First, a systematic search was conducted to identify relevant literature from multiple databases, including PubMed, Web of Science, Scopus, Embase, and African Index Medicus. Second, clinical trial registries, including ClinicalTrials.gov, World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP), the Pan African Clinical Trials Registry (PACTR), and the South African National Clinical Trials Register (SANCTR), were also searched.

Search strategy

Search terms included combinations of keywords and subject headings related to vaccine interventions, trials, Africa, and vaccine preventable diseases, such as “vaccine,” “immunization,” “clinical trial,” “intervention,” “Africa,” “African countries,” and “COVID-19” (or “SARS-CoV-2”) (see Annex 1). The search was limited to articles published in English and French from January 2010 to the most recent available data, aiming to identify a comprehensive range of studies that met the inclusion criteria for this review. Data for ongoing clinical trials were sourced from the ICTRP portal and ClinicalTrials.gov. The ICTRP, a World Health Organization (WHO) initiative, aggregates trial data from 17 national and regional registries, establishing a unified access point for global clinical trial information.

Selection of sources of evidence

Titles and abstracts were screened for eligibility by two independent experts, Prof. Jean B. Nachega and Prof. Olalekan A. Uthman, using Covidence (https://www.covidence.org). Full-text articles were obtained for potentially eligible studies and further assessed for inclusion. Cross-checking and any disagreements were resolved through consultation with one independent team member, Prof. Patrick D.M.C. Katoto. Studies were eligible for inclusion if they involved vaccine interventions or trials conducted in any country or region in Africa and reported primary data on the source of funding or output results. Studies that were conducted before January 2010, conducted outside Africa, involved non-experimental designs, were based on analysis of secondary interventional data, and trials published only l as conferences abstracts were excluded.

Data charting process

A data collection form was developed to guide the extraction of relevant information from the included studies. This form was pilot tested on a random sample of included studies and refined as necessary. Extracted data included study characteristics (e.g., publication year, authors, study design), vaccine intervention or trial information (e.g., disease targeted, vaccine type, trial phase), location (country and region), source of funding, and results. See Annex 2 for a table describing each data element.

Data item definition

In the study, a broad spectrum of outcomes related to vaccine trials in Africa was mapped and analyzed. Descriptive trial data were study phase, trial country location, primary funder (e.g., academia, multilateral organization, pharma, and philanthropic organizations). Methods of trial recruitment, ranging from public notices and media outreach to recommendations from healthcare providers and hospital-based recruitment efforts were scrutinized. Clinical trials sample sizes were categorized into four groups: ‘Small’ for less than 100 participants, ‘Medium’ for 100 to 1,000, ‘Large’ for 1,000 to 10,000, and ‘Very Large’ for over 10,000. The clinical trials were categorized into different phases: Phase 1, Phase 1/2, Phase 2, Phase 2/3, Phase 3, and Phase 4. Study populations were categorized as adults, adolescents, children, pregnant women, immunocompromised individuals, and the elderly. Intervention targets were defined as pathogens (virus vs parasite vs bacteria) and health conditions for which the studied vaccines were directed. Vaccine types were categorized based on vaccine platform and technologies used for development and manufacture (e.g., inactivated, live-attenuated, mRNA vaccines, and others. Furthermore, the study documented the outcomes related to vaccine efficacy, effectiveness, safety, delivery methods, and acceptability to shed light on the primary limitations faced in implementing vaccine trials across Africa. The proportion of participants lost to follow-up was also collected.

Data synthesis and analysis

The extracted data from the selected studies were synthesized and reported in a narrative format to provide an overview of the extent, range, and nature of vaccine interventions and trials conducted in Africa before and during the COVID-19 pandemic. Descriptive statistics were used to summarize the distribution of vaccine interventions and trials by country, region, source of funding, and output results. To facilitate an in-depth exploration of data, we developed an interactive web dashboard, designed to provide a comprehensive exploration and visualization of the data. We used R version 4.3.2 and Python Pandas for all analyses. The results were reported following the PRISMA-ScR guidelines,¹¹ with the study selection process presented in a PRISMA flow diagram and the main findings reported in a narrative format supported by tables, figures, and network maps (See Annex 3).

Ethical approval

As this was a mixed scoping review and bibliometric analysis using data from open and publicly available sources, there was no institutional requirement for ethical approval.

Results

Selection of sources of evidence

Our search strategy identified 4,657 records through various databases and an additional 878 records from clinical trial registries (Figure 1). Following the removal of 1,054 duplicates, we screened 3,603 records from the databases and subsequently assessed 334 for eligibility. Five hundred and twelve records retrieved from trial registries were directly evaluated for eligibility. During the assessment phase, 161 records were excluded for reasons including, but not limited to, clinical location of the trial, post-hoc analyses, unsuitable study designs, and irrelevant population groups. Specifically, from the database search, exclusions included 27 records for wrong settings, 20 for post-hoc analyses, and 12 for wrong study design. In contrast, from the trial registries, 102 records were excluded because the trials had already been published. Ultimately, our scoping review included 662 vaccine trials, with 252 from completed and published studies in peer-reviewed journals. The remaining 410 trials were identified from clinical trial registries.

Figure 1.

PRISMA flow for study selection.

Characteristics of sources of evidence

Table S1 provides a detailed description of included published studies. When reported, the trials were published between 2011 and 2023. Almost 50% of the trials were published after 2018. Of the 662 trials, 252 were completed and published in academic journals (38%), another 44 studies were completed (7%) but are yet to be published. The majority are either not recruiting (271 studies, 41%) or are currently recruiting (73 studies, 11%). A small number have been terminated (2 studies, 0.30%), or have been withdrawn (1 study, 0.15%). The highest number of trials were conducted in South Africa (n = 220 trials), followed by Kenya (n = 88), Uganda (n = 52), Mali (n = 44), Tanzania (n = 41), and Burkina Faso (n = 41) (Figure 2). These six countries accounted for almost 60% of the trials from Africa. Most of the trials were conducted in one country (n = 637). The trials predominantly focused on infectious diseases, with viral infections being the most common condition studied (209 trials). Bacterial and parasitic infections were also significant areas of focus, with 64 and 58 trials, respectively. The settings for these trials varied, with about 55 trials conducted in hospitals, health centers, and clinics. Community-based settings and multicentre or international studies also featured prominently, showcasing the varied environments in which these studies took place. Regarding the populations targeted, the general population was most frequently involved in the trials, accounting for 289 studies.

Figure 2.

Number of trials by country.

Of the trials that reported age category of the participants (Annex 5), adults constituted the predominant age category (366 trials, 55.3%), followed by children (138 trials, 20.9%) and infants (80 trials, 12.1%). Only a small fraction targeted elderly populations (2 trials, 0.3%) or pregnant women (20 trials, 3.0%), while 8.5% of trials (56) included mixed age populations.

The distribution of sample sizes largely mirrored this pattern, with adult participants representing 60.7% (1,115,001) of the total enrollment. Children accounted for 15.7% (288,938) of participants, and mixed populations comprised 14.1% (259,168). Infant trials, while representing 12.1% of studies, accounted for only 6.3% of total participants (116,300). Similarly, trials focusing on pregnant women and elderly populations represented small proportions of the total sample size at 1.0% (19,046) and 2.1% (37,832), respectively.

An analysis of vaccine clinical trials conducted in Africa by phase demonstrated a relatively balanced distribution across early and late-stage development (Annex 6). Phase 1 trials were most prevalent (132 trials, 19.9%), closely followed by Phase 2 (128 trials, 19.3%) and Phase 3 (126 trials, 19.0%). Post-marketing Phase 4 studies comprised 8.3% of trials (55). Combined phase trials were less common, with Phase 1/2 representing 3.8% (25), Phase 2/3 at 1.5% (10), and Phase 1/2/3 at 4.8% (32). Only one Phase 0 trial (0.2%) was identified.

The distribution of participants across phases revealed a different pattern, with Phase 3 trials enrolling the largest proportion of participants (656,922, 35.8%), followed by Phase 4 (388,387, 21.2%) and Phase 1 (265,814, 14.5%). Despite the similar number of Phase 2 trials compared to other phases, they enrolled a substantially smaller percentage of total participants (89,486, 4.9%). Multi-phase trials showed varying enrollment patterns, with Phase 2/3 trials accounting for 3.2% of participants (59,268), Phase 1/2/3 comprising 4.0% (73,945), and Phase 1/2 enrolling only 0.4% (6,550). The single Phase 0 trial included just 108 participants.

We have presented a dashboard including advanced data visualization tools, to facilitate more a more detailed exploration of trends, patterns, and relationships within our dataset. This innovative tool is accessible at https://afrivactrials.streamlit.app/ (see Annex 4 for additional details). The app features an At-a-Glance Summary Dashboard for quick insights into trial phases and publication status, visualized using heatmaps by country and year. The Trends feature offers a longitudinal analysis of trial data changes over time, while the Visual Analysis tool provides intuitive graphical data representations. The Data Explorer facilitates in-depth dataset analysis with advanced filtering and search capabilities. An AI-powered Ask Me Anything tool enables real-time data inquiries, complemented by a References section that houses a repository of supporting sources and studies.

Comprehensive analysis of vaccine research trends: from development phases to funding and manufacturing dynamics pre- and post-COVID-19

Figure 3(a) shows the number of published vaccine clinical trials in Africa by phase from 2004 to 2023, with a delineation between pre- and post-COVID-19 periods indicated by a dashed green and red line at the year 2020. The number of published trials increased after the onset of the COVID-19 pandemic in March 2020. Prior to 2020, the count of trials was low, with the highest number reaching just above 10 in any given year. Post-COVID-19, there is a significant spike in activity, with the count of trials increasing markedly in 2021 and 2022. More early phase vaccine trials have been conducted in Africa in the post-COVID-19 period Late phase trials also increased but to a lesser extent. Notably, during 2021 and 2022, trials covering multiple phases were conducted, which was not observed during the pre-COVID-19 period.

Figure 3.

Temporal trends in vaccine research: phase, condition, and vaccine type pre- and post-COVID-19.

As shown in Figure 3(b), vaccine trials for viral infections were the trials most frequently conducted s across the entire time span, with a substantial increase in publications post-COVID-19, particularly in 2021 and 2023 when the count exceeds 50. Trials for bacterial infections were done less frequently; their numbers increased slightly after the COVID-19 pandemic but remain relatively low in comparison to vaccine trials for viral pathogens. Vaccine trials targeting parasitic infections have been largely directed against malaria. Cancer, as a condition category, is scarcely represented with only a few trials published, and shows no significant change in the post-COVID-19 era.

Subunit and protein vaccine trials have been consistently conducted throughout the years (Figure 3(c)) with a notable increase in the post-COVID-19 period, with the highest count observed in 2021 and 2023. Trials of viral vector vaccines have also increased after COVID-19, a category that was not represented before 2020. Trials of mRNA vaccines, emerge in the post-COVID-19 era, with counts beginning in 2021 and continuing into 2023, reflecting the rapid development and interest in this technology due to the COVID-19 pandemic. Inactivated and killed vaccines showed a moderate presence throughout, with a slight increase after the COVID-19 pandemic. Trials of DNA vaccines have been done sporadically with no clear trend post-COVID-19. Combination and conjugate vaccines are less frequent overall, with some presence in the post-COVID-19 period.

Figure 4(a) outlines trends in vaccine trial manufacturer categories conducting vaccine trials in Africa from 2010 to 2024. Most earlier vaccine trials conducted in Africa have been sponsored by pharmaceutical companies, with a small but consistent number conducted by government and academic institutions pre-COVID-19. Since 2020, coinciding with the onset of the COVID-19 pandemic, a significant increase in the number of pharmaceutical-sponsored trials has occurred. This trend continues in 2021 and 2022, with these years showing the highest number of trials overall and the pharmaceutical category dominating the sponsorship of trials.

Figure 4.

Evolution of vaccine research funding and manufacturing dynamics before and after COVID-19.

Our analysis of funding sources for vaccine clinical trials in Africa reveals distinct patterns in organizational and geographical distribution (Figures 4(b) and 5). The Bill & Melinda Gates Foundation emerged as the predominant individual funding organization, supporting 41 trials, followed by the National Institutes of Health (NIH) with 23 trials (Annex 7). Other significant funders included the European and Developing Countries Clinical Trials Partnership (EDCTP) and Wellcome Trust (12 trials each), while pharmaceutical companies such as GlaxoSmithKline, Janssen Research & Development, and Sanofi Pasteur contributed to a combined total of 14 trials among the top funders.

Figure 5.

Funding organization types by country of origin for vaccine trials in Africa.

Examination of the geographical origins of funding sources demonstrated a pronounced concentration in high-income countries (Annex 8). The United States led with 110 funding organizations, more than double the United Kingdom (52), which ranked second. The European Union collectively represented the third largest funding source (27), while South Africa was the only African country among the top funding countries, ranking fourth with 14 organizations. Other notable funding countries included Denmark (10), China (6), and France (5).

Further analysis of the relationship between organization types and their countries of origin (Figure 5) showed that foundations and NGOs from the USA (44) constituted the single largest funding category-country combination, followed by government agencies from the USA (29). The European Union primarily funded trials through international organizations (27), while the UK funded a more balanced mix of foundations/NGOs (20) and government agencies (12). South African funding was predominantly through government agencies (8) and pharmaceutical/biotech companies (6).

Network analysis of co-funding relationships (Annex 9) revealed strategic collaborations centered around major funders. The Bill & Melinda Gates Foundation demonstrated the most extensive collaboration network, with strong connections to GlaxoSmithKline Biologicals, PATH, Wellcome Trust, and several research institutes. Other significant co-funding clusters included partnerships between UK research councils and international development agencies, and between Wellcome Trust and NIH.

Discussion

This scoping review and bibliometric analysis provides key insights into vaccine research trends in Africa before, during, and after the COVID-19 pandemic. The findings reveal a notable increase in vaccine trials, likely driven by crises such as the COVID-19 pandemic, and reflecting a growing commitment to vaccine development across the continent.

The analysis highlights the broad geographical distribution of vaccine trials in Africa, with significant activity in South Africa, Kenya, and Uganda, which underscores Africa’s expanding role in global vaccine research.¹² A strong emphasis on pediatric trials, particularly for malaria and pneumococcal vaccines, addresses the urgency of protecting vulnerable populations. The dominance of Phase 3 trials signals progress in African participation in late-stage vaccine development but also exposes a gap in investment in early-stage research (Phases 1–2) – a critical area for fostering innovation and accelerating vaccine breakthroughs.^12–14

The scope of vaccine types in clinical trials in Africa is wide, encompassing everything from traditional inactivated vaccines to cutting-edge mRNA technologies.¹⁵ This variety reflects the innovative spirit driving vaccine research on the continent as well as the need for thorough evaluation of the safety and immunogenicity of new vaccines. The trials reported exhibit a range of sample sizes, with some studies engaging thousands of participants to ensure data reliability. The acknowledgment of research limitations, such as small sample sizes and the predominance of single-center studies, alongside concerns over high loss-to-follow-up rates, reveals a culture of transparency and critical self-reflection within the African vaccine trials community. Such acknowledgments highlight ongoing challenges in completing vaccine trials in resource-limited settings, and stress the importance of developing effective strategies for participant retention to enhance the validity and applicability of research outcomes.¹⁶

The dynamic and collaborative vaccine trial landscape in Africa is further illustrated by the participation of a variety of vaccine manufacturers, from global pharmaceutical giants to emerging biotech firms (Table 1).¹⁷ This diverse involvement signals a robust vaccine trial ecosystem supported by significant contributions from key funding entities, including the Gates Foundation and various philanthropic and government bodies. Despite recent progress, critical gaps in vaccine trial capacity remain, such as limited number of African countries participating I vaccine trials, the absence of some major vaccine manufacturers in the African region, and insufficient focus on high burden neglected diseases. Additionally, the disparity between COVID-19 and non-COVID-19 trials in recent years calls for a more balanced research agenda that addresses both pandemic-related needs and ongoing local and regional health challenges.

Table 1.

Summary of African vaccine manufacturing landscape: current state and future prospects (adapted from (“Mapping African vaccine production infrastructure,” n.d.).

Key Points	Details
Location, Capability, and Capacity Limitations	Manufacturing predominantly limited by geographical location, technical capabilities, and overall production capacity.
Focus on COVID-19 Vaccine Fill/Finish	Primary activity is the fill/finish process for COVID-19 vaccines.
Capacity Commitments	Committed fill/finish capacity exceeds 500 million doses annually, concentrated in North and South Africa.
Active and Planned Facilities	Countries like South Africa, Algeria, Morocco, and Egypt have initiated or are planning fill/finish operations. The estimated production rates might be optimistic.
Potential for Capacity Expansion	Some facilities could potentially increase their vaccine production capacity, but there are limitations for manufacturing viral vaccines.
Transition Post-COVID-19	Potential for existing fill/finish capacities to be repurposed for different types of vaccines post-COVID-19.
Impact of COVID-19 on Manufacturing Landscape	Significant investment projects triggered by the pandemic are altering the landscape, adding comprehensive end-to-end manufacturing and further fill/finish capabilities.
Notable Projects	Major projects include Senegal MADIBA (mRNA and fill/finish), South Africa mRNA transfer hub (mRNA), South Africa NantSA (viral vector and fill/finish), Egypt MINAPHARM (viral vector and recombinant proteins), and Morocco RECIPHARM (fill/finish).
Future Prospects and Challenges	Although new mRNA and viral vector capacities may be hard to adapt to other products, the existing and upcoming fill/finish capacities form a strong foundation for a pan-African network.

Among the priorities for health policymakers, is the need to foster an equitable allocation of resources and the establishment of advanced research infrastructure for vaccine trials throughout the African continent. This entails providing dedicated support and funding for countries and regions with less vaccine trial capacity.¹⁸ Additional state-of-the-art research facilities using cutting-edge technology, and a skilled workforce are needed. Such resources are crucial not only for executing vaccine trials but also for empowering African nations to autonomously tackle their specific health challenges.¹⁹ While diseases such as malaria, HIV, and tuberculosis have garnered significant attention, research in other underrepresented endemic diseases such the ongoing dengue outbreak is needed.²⁰ Policies aimed at strengthening international and inter-institutional collaborations, through partnerships and data sharing initiatives, could markedly increase vaccine trial capacity in Africa.

The future vaccine trial research agenda in Africa should prioritize the establishment of uniform data reporting standards to foster consistency and facilitate the comparison of data across studies. Investigating the socio-economic and political factors that influence the choice of trial locations, and their success may reveal broader systemic challenges and opportunities in Africa.^21,22

This study provides a detailed analysis of vaccine trials conducted in Africa since 2010. By examining a wide range of vaccine types, developmental stages and sponsors it offers a comprehensive perspective on vaccine research on the continent. The use of rigorous methodology, combining scoping review and bibliometric analysis, strengthens the generalizability of its findings to inform future vaccine trial capacity development in Africa.

Our study has several limitations. Funding transparency issues may affect perceived impartiality, while the study’s primary reliance on quantitative data excludes qualitative aspects such as participant experiences and community factors. Additionally, the underrepresentation of non-English publications in the public domain may not fully capture the breadth of vaccine research across linguistically diverse African regions.

Conclusion

Our analysis reveals a dynamic expansion in vaccine trials across Africa, indicating a promising trend in health research and public health improvement. However, it also identifies critical needs for more equitable distribution of resources and research efforts These insights are pivotal for shaping future vaccine research and policy directions, ensuring that Africa’s unique health challenges are addressed through collaborative and strategic support.

Biography

Jean Nachega, MD, PhD, MPH, FRCP, DTM&H, is a Professor Extraordinary at Stellenbosch University Faculty of Medicine and Health Sciences in Cape Town, South Africa; a tenured Associate Professor of Epidemiology, Infectious Diseases, and Microbiology at the University of Pittsburgh, USA; and an Adjunct Associate Professor of Epidemiology and International Health at the Johns Hopkins Bloomberg School of Public Health in Baltimore, MD, USA. He received his training in Belgium (University of Louvain), the UK (London School of Hygiene & Tropical Medicine), and the USA (Johns Hopkins University & Harvard University). With over 20 years of experience in patient care, teaching, and the design and implementation of infectious diseases research and training programs funded by NIH/NIAID, PEPFAR, EDCTP, and the Wellcome Trust, Dr. Nachega has authored more than 240 peer-reviewed publications. Dr. Nachega serves as an ad hoc expert consultant for the Bill and Melinda Gates Foundation, the US-CDC, and the WHO. He is also a member-elect of the Academy of Sciences of South Africa (ASSAf) and the African Academy of Sciences (AAS).

Funding Statement

This work was supported by Sanofi Vaccines Division. Hertford Office Park, Midrand, South Africa.

Disclosure statement

Thinus Marais and Amine Amiche are Sanofi employees and may hold shares and/or stock options in the company

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/21645515.2025.2481802

Patient public involvement Statement

Given the retrospective scoping review design, patients or the public were not involved in the design, or conduct, or reporting, or dissemination plans of our research.