Meeting report: CEPI consultation on accelerating access to novel vaccines against emerging infectious diseases for pregnant and lactating women, London, 12-13 February 2020

The exclusion of pregnant women from an Ebola vaccine trial in Boende, western DRC: Perceptions of female participants who became pregnant and community members

Pregnant women are often underrepresented in clinical trials. However, there is a growing push for more inclusion after multiple disease outbreaks, like COVID-19, Zika, and Mpox disproportionately affected them. Qualitative research has primarily focused on the experiences of pregnant women who choose to participate or decline participation in trials. To our knowledge, there has been no research on the perspectives of those who were excluded from trials upon becoming pregnant. To address this gap, we explored the views of women excluded from a phase 2 Ebola vaccine trial, as well as those of the broader community in Boende, Democratic Republic of the Congo. Through individual interviews and focus group discussions, we found that protecting the foetus was paramount for the women, leading to general acceptance of their exclusion from the trial. Trust in trial organisers' knowledge, and the absence of an active Ebola outbreak at the time of the trial, may have supported this acceptance. Community perceptions generally aligned with those of the excluded women interviewed. However, the exclusion seemed to have impacted the decision to participate for a proportion of women of reproductive age. This was observed when some interviewed women reported declining participation in the trial due to their desire to conceive during the trial period. This study illustrates how women made pragmatic decisions regarding trial participation within the decision space available to them. Our findings seem to support established norms of special care for safety during pregnancy and echo sentiments described elsewhere in the literature. These results, coupled with the growing demands for the inclusion of pregnant women, highlight the necessity of finding a balance between prioritising the safety of women and their foetuses, and the autonomy of pregnant women, enabling them to make informed choices through comprehensible informed consent processes.

Safety, immunogenicity, efficacy, and effectiveness of Lassa fever vaccines in pregnant persons, children, and adolescents: a protocol for a living systematic review and meta-analysis

BACKGROUND

Lassa fever (LF), caused by the Lassa virus (LASV), is a zoonotic viral hemorrhagic disease endemic to West Africa, primarily transmitted through rodent excreta and infected bodily fluids. It poses significant public health challenges due to its high morbidity and mortality rates, particularly among at-risk populations like pregnant persons and children. Despite decades of research, vaccine development has been hindered by the virus's genetic diversity and complex epidemiology. While several vaccine candidates have been developed, none have received regulatory approval. Given the rapidly evolving vaccine landscape, a living systematic review (LSR) was selected to enable real-time evidence synthesis. This protocol outlines a living systematic review (LSR) to evaluate the safety, efficacy, effectiveness, and immunogenicity of LASV vaccines, providing evidence to guide public health interventions and vaccine recommendations.

METHODS

We will conduct a biweekly updated LSR and meta-analysis, systematically searching databases (e.g., MEDLINE, EMBASE, CENTRAL) and clinical trial registries from January 2014 onward to identify studies of LASV vaccines in pregnant persons, children, and adolescents. All study designs, including randomized trials, cohort studies, case-control studies, and case reports, will be eligible. Pairs of reviewers will independently assess eligibility, extract data, and evaluate the risk of bias. Primary outcomes include vaccine safety, efficacy, and effectiveness in pregnant persons (including neonatal outcomes), children, and adolescents, while secondary outcomes assess immunogenicity and reactogenicity. Data on adult populations will also be included, and results on this group will be reported as available. We will conduct paired meta-analyses, including prespecified subgroup and sensitivity analyses. We will use the grading of recommendations assessment, development, and evaluation approach to evaluate the certainty of evidence.

DISCUSSION

This LSR offers a dynamic framework to generate timely evidence on LASV vaccines for vulnerable populations. By integrating findings into an interactive Microsoft Power BI dashboard, stakeholders can access and utilize real-time updates to inform public health strategies. Despite challenges like study heterogeneity and vaccine platform variability, subgroup and sensitivity analyses will mitigate these issues. This review aims to support clinical trial designs, guide policy, and improve health outcomes in Lassa fever-endemic regions.

STUDY REGISTRATION

Two protocols were registered in the International Prospective Register of Systematic Reviews (PROSPERO) database: CRD42024514513 and CRD42024516754.

Burden of Lassa fever disease in pregnant women and children and options for prevention

Lassa fever is a serious epidemic viral disease in West Africa affecting an estimated 2 million people annually with about 5000-10,000 deaths, although supporting data is sparse. Lassa fever significantly affects neonates, children, and pregnant women, however, comprehensive data on its impact in these populations are lacking. We reviewed the available literature on Lassa fever to assess its prevalence and impact in these populations and implications for vaccine development. Clinical features in children were similar to those observed in adults, with complications such as bleeding. Altered mental status, anasarca (swollen baby syndrome), bleeding, and poor urine output were risk factors for death. The case fatality rate (CFR) in 16 paediatric studies ranged from 6 % to 63 % and was 66.7 % and 75.0 % in two neonatal studies. In a systematic review of studies on pregnant women the CFR was 33.73 %. The adverse foetal outcomes included miscarriage, stillbirth, and intrauterine death associated with maternal death. Since Lassa fever significantly affects neonates, children, and pregnant women, developing a safe and effective, single-dose vaccine for these high-risk populations is vital. Currently, there are four clinical trials assessing Lassa virus vaccines. Only one of these trials is enrolling children aged ≥18 months, and exclude pregnant and breast-feeding women. It is essential that pregnant and breast-feeding women and young children are included in clinical trials that incorporate robust safety surveillance and risk mitigation measures. In our review, potential approaches to address the specific gaps in the areas of diagnosis, management, and prevention of Lassa fever in these specific populations, such as disease surveillance systems and vaccine development, were identified. A comprehensive strategy with investment focused on addressing specific knowledge gaps will be essential in protecting the health of these specific populations in Lassa virus endemic regions.

Opportunities and challenges to the development and deployment of vaccines for pregnant women in Germany

Maternal immunisation is a powerful tool to protect both pregnant women and their children. A new maternal RSV vaccine holds promise to protect newborns from RSV-associated illness in the first few months of life, but no official recommendation has been made in Germany. Since RSV causes a significant burden of paediatric hospital admissions, we consider it a pertinent opportunity to review barriers to maternal vaccination in Germany, which might also apply to other settings. Access to vaccination for pregnant women in Germany is shaped by an interplay of legal, regulatory, institutional, and sociocultural factors, with a less permissive clinical research environment, delays in recommendation and roll-out, and lower acceptance by healthcare professionals and the population. Actionable recommendations to improve availability and uptake include coordination with other national regulatory bodies to reduce delays, awareness and literacy campaigns for health professionals and the general public, and capacity building for vaccine clinical research.

The inclusion of pregnant women in vaccine clinical trials: An overview of late-stage clinical trials' records between 2018 and 2023

Pregnant women are generally excluded from clinical research over safety concerns. However, demands to include them in clinical vaccine development have intensified after recent COVID-19, Ebola, and Lassa fever outbreaks given the disproportionate effect of these diseases on pregnant women and/or their foetuses. Numerous studies highlighted the scarcity of safety data for therapeutic interventions in pregnant women. Nevertheless, only a small number have assessed the number of vaccine trials including this population. Therefore, we searched for phase 3 and 4 vaccine clinical trials in healthy populations registered between 2018 and 2023 in clinicaltrials.gov and the International Clinical Trial Registry Platform. Out of 400 registered vaccine trials matching our inclusion criteria, 217 (54 %) were industry-sponsored, and 222 (56 %) had COVID-19 as a target. We found 22 studies (6 %) that either were designed for pregnant women or included them as part of a larger population. Out of these 22 trials, 13 were designed specifically for pregnant women; seven of these were maternal vaccines aiming at protecting the foetus, namely pertussis (3), Respiratory Syncytial Virus (RSV) (3), and meningitis plus tetanus (1) vaccines, and six others targeted either flu (3), COVID-19 (2) or Ebola (1). Only the RSV and Ebola vaccine trials were industry-sponsored. We also found that nine studies targeting the general population included pregnant women. These focused on COVID-19 (3), flu (2), COVID-19 + flu (2), Ebola (1), and Hepatitis B (1). None of these studies was industry-sponsored. Our findings show that a gap still exists in terms of pregnant women's inclusion in vaccine trials. Such a gap needs to be tackled urgently to minimise the devastating effects that a future infectious disease outbreak could have on this population. This study can inform future demands for increased inclusion, especially in industry-sponsored trials, as it provides an overview of the current vaccine trials scene.

Evaluation of non-clinical toxicity studies of COVID-19 vaccines

In this study we evaluated the outcomes of non-clinical toxicity studies of various SARS-CoV-2 vaccines produced with different manufacturing technologies, with focus on Repeated Dose Toxicity (RDT) and Developmental and Reproductive Toxicity (DART) studies. We found that RDT and DART studies at doses relevant for human treatment showed no adverse effects while remaining observations were expected findings including local reactogenicity, immune response and macroscopic findings at the injection site. We have also reviewed the European Medicines Agency (EMA) nonclinical assessment reports for market authorization. Regardless of utilized vaccine manufacturing technology EMA assessment of the non-clinical studies consisted most frequently of comments related to study design, species selection and missing data. Sponsors have often submitted platform studies (vaccine studies with the same technology/construct but using other antigens) as supplementary data. Animal model-based toxicity testing has shown rather small effects, which have been never serious adverse effects. The translational value to support clinical development is mainly to inflammatory effects, indicative of the primary action of the vaccines. From a 3R perspective supportive platform technology data consisting of previously executed RDT and DART studies from the same platform technology are encouraged to be implemented in the vaccine assessment process.