Ebola Vaccine Research Articles

Lung-Targeted Transgene Expression of Nanocomplexed Ad5 Enhances Immune Response in the Presence of Preexisting Immunity

Recombinant adenovirus serotype 5 (Ad5) vector has been widely applied in vaccine development targeting infectious diseases, such as Ebola virus disease and coronavirus disease 2019 (COVID-19). However, the high prevalence of preexisting anti-vector immunity compromises the immunogenicity of Ad5-based vaccines. Thus, there is a substantial unmet need to minimize preexisting immunity while improving the insert-induced immunity of Ad5 vectors. Herein, we address this need by utilizing biocompatible nanoparticles to modulate Ad5–host interactions. We show that positively charged human serum albumin nanoparticles ((+)HSAnp), which are capable of forming a complex with Ad5, significantly increase the transgene expression of Ad5 in both coxsackievirus–adenovirus receptor-positive and -negative cells. Furthermore, in charge- and dose-dependent manners, Ad5/(+)HSAnp complexes achieve robust (up to 227-fold higher) and long-term (up to 60 days) transgene expression in the lungs of mice following intranasal instillation. Importantly, in the presence of preexisting anti-Ad5 immunity, complexed Ad5-based Ebola and COVID-19 vaccines significantly enhance antigen-specific humoral response and mucosal immunity. These findings suggest that viral aggregation and charge modification could be leveraged to engineer enhanced viral vectors for vaccines and gene therapies.

Ebola Virus Disease (Evd): Nigeria Perspective

The deadly but uncommon Ebola virus disease affects both humans and primates (EVD). The Ebola virus causes a severe form of hemorrhagic fever in which the victim’s blood clots abnormally, leading to internal bleeding. After initial contact with the virus, "dry" symptoms such as fever, aches and pains, and exhaustion typically appear, followed by "wet" symptoms such as diarrhoea and vomiting anywhere from two to twenty-one days (on average, eight to ten) later Virologists believe Laupland and Valiquette are hosting the virus. It is believed that the onlyway for the Ebola virus to spread is through direct contact between people and blood or other body fluids from a person showing symptoms of the disease. Saliva, mucus, vomit, faeces, tears, perspiration, breast milk, urine, and sperm all contain the Ebola virus. The term "spillover" is used to describe the zoonotic spread of the Ebola virus from infected hosts like the fruit bat or nonhuman primates to other animals. The Ebola virus is amember of the viral family known as Filoviridae in the order of Mononegavirales the Marburg virus is also. Ebola virus infection can be diagnosed through a variety of techniques, including electron microscopy, antigen capture detection tests, serum neutralisation tests, reverse transcriptase polymerase chain reaction (RT PCR) assays, antibody-capture enzyme-linked immunosorbent assays (ELISAs), and virus isolation through cell culture. The term "Ebola vaccine" refers to both already available and planned vaccines against the virus. Only Zaire ebolavirus and rVSV-ZEBOV vaccines are effective against this disease. Treatment that is purely supportive, such as relieving patients of their symptoms and giving them water orally or intravenously, does not improve prognosis. This research intends to give Nigerians an up-to-date picture of the spread of EVD in the country in the wake of the recent pandemic in neighboring Uganda.

Factors Influencing COVID-19 Vaccine Refusal in an Unstable SocioPolitical Area: The Case of Eastern of the Democratic Republic Congo

The purpose of this research was to identify factors that affect the resistance of the population of eastern DR Congo to be vaccinated against Covid-19. Therefore, quantitative research based on primary data obtained from a survey was conducted in North Kivu Province. The questionnaire had 35 items with 410 respondents. After processing of the data, 318 records were retained. There were 151 women (48.55%) and 160 men (51.45%). Using the exploratory factor analysis (EFA), the authors shifted from 35 items to 6 main factors affecting vaccine resistance when they used Cronbach's Alpha test for each rotated factor. Cronbach's Alpha test for the reliability of the questionnaire was 0.67; the Bartlett test was 2490.79, and the KMO test was 0.70. Total cumulative variance was 30.1% explained by the six retained which are Psycho-medical background, Demographic, Social origin, Lack of trust in government actions, Previous issues about the Ebola vaccine in North Kivu, and Socio-political belonging.

Addressing the Threat of Emerging Viral Infections.

Emerging infections are caused when microorganisms that are maintained in a reservoir where they cause no harm, transmit from the reservoir to a new host. I have been studying the replication, molecular basis for pathogenesis, and host responses to emerging viruses, including influenza virus, Ebola virus, and SARS-CoV-2, and using the knowledge gained from these studies to develop antivirals and vaccines.Influenza viruses cause epidemics every winter, but occasionally new influenza viruses emerge and spread worldwide (pandemic). We established a technique that allows us to make influenza viruses artificially. This technique is now widely used for basic research and for the development of vaccines against highly pathogenic avian influenza virus for pandemic preparedness and live attenuated influenza vaccines. Using this technique, we elucidated the mechanisms of emergence of pandemic viruses, viral replication, and the molecular mechanism of pathogenesis.Ebola virus causes severe disease with a mortality rate of up to 90%. In 2013, a major outbreak of Ebola virus began in West Africa that led to nearly 30,000 people being infected and a death toll of over 10,000 people. During the outbreak, we established a laboratory in Sierra Leone and used samples from Ebola patients to study host responses and identify biomarkers for severe infection. We also established a technology to artificially make Ebola virus and used this technology to make an Ebola virus that grows only in a particular cell line. Using this virus, we produced an inactivated Ebola vaccine, which was shown to be safe and effective in a Phase I clinical trial.Late in 2019, SARS-CoV-2 emerged in Wuhan, China and has since caused unprecedented damage globally. In our laboratory, we established an animal model for this infection and have used it to evaluate pathogenicity, efficacy of therapeutic monoclonal antibodies and antivirals, and to develop vaccines.In my presentation, I will discuss our findings regarding these emerging viral infections.

Maternal Immunization Using a Protein Subunit Vaccine Mediates Passive Immunity against Zaire ebolavirus in a Murine Model.

The Ebola virus has caused outbreaks in Central and West Africa, with high rates of morbidity and mortality. Clinical trials of recombinant virally vectored vaccines did not explicitly include pregnant or nursing women, resulting in a gap in knowledge of vaccine-elicited maternal antibody and its potential transfer. The role of maternal antibody in Ebola virus disease and vaccination remains understudied. Here, we demonstrate that a protein subunit vaccine can elicit robust humoral responses in pregnant mice, which are transferred to pups in breastmilk. These findings indicate that an intramuscular protein subunit vaccine may elicit Ebola-specific IgG capable of being transferred across the placenta as well as into the breastmilk. We have previously shown protective efficacy with these vaccines in non-human primates, offering a potential safe and practical alternative to recombinant virally vectored vaccines for pregnant and nursing women in Ebola endemic regions.

Non-human primate to human immunobridging demonstrates a protective effect of Ad26.ZEBOV, MVA-BN-Filo vaccine against Ebola

Without clinical efficacy data, vaccine protective effect may be extrapolated from animals to humans using an immunologic marker that correlates with protection in animals. This immunobridging approach was used for the two-dose Ebola vaccine regimen Ad26.ZEBOV, MVA-BN-Filo. Ebola virus (EBOV) glycoprotein binding antibody data obtained from 764 vaccinated healthy adults in five clinical studies (NCT02416453, NCT02564523, NCT02509494, NCT02543567, NCT02543268) were used to calculate mean predicted survival probability (with preplanned 95% confidence interval [CI]). We used a logistic regression model based on EBOV glycoprotein binding antibody responses in vaccinated non-human primates (NHPs) and NHP survival after EBOV challenge. While the protective effect of the vaccine regimen in humans can be inferred in this fashion, the extrapolated survival probability cannot be directly translated into vaccine efficacy. The primary immunobridging analysis evaluated the lower limit of the CI against predefined success criterion of 20% and passed with mean predicted survival probability of 53.4% (95% CI: 36.7–67.4).

Changing gear: Experiences of how existing qualitative research can adapt to an unfolding health emergency.

Long-term research projects are not always able to adapt to a new crisis and incorporate characteristics and approaches of rapid research to produce useful data quickly. Project AViD was a programme of research that ran between 2018 and 2022 to examine factors that shape vaccine confidence. The project initially focused on five country case studies looking at vaccines for Ebola, Measles, Rift Valley Fever and Zika. The COVID-19 pandemic emerged during this time and provided an opportunity to contribute to the pandemic's 'million-dollar question'-how to deploy COVID-19 vaccines. Drawing on our experience as researchers, and specifically from AViD, we propose seven factors that can influence when and how longer-term qualitative research projects can adapt and contribute to the response to an unfolding health emergency. These include: (1) the phase of research in which the emergency hits; (2) the relative significance of the emergency in the research setting; (3) the specific methods and research team capacities; (4) existing operational links; (5) supportive ecosystems; (6) flexibility in research contracting and funding; and (7) the research team attitude and approach. We close with two considerations for longer-term research projects that find themselves having to "change gear" amid a public health emergency-the need to re-assess risks and benefits and the need to protect equitable partnerships.

Safety and immunogenicity of an Ad26.ZEBOV booster dose in children previously vaccinated with the two-dose heterologous Ad26.ZEBOV and MVA-BN-Filo Ebola vaccine regimen: an open-label, non-randomised, phase 2 trial

Children account for a substantial proportion of cases and deaths during Ebola virus disease outbreaks. We aimed to evaluate the safety and immunogenicity of a booster dose of the Ad26.ZEBOV vaccine in children who had been vaccinated with a two-dose regimen comprising Ad26.ZEBOV as dose one and MVA-BN-Filo as dose two. We conducted an open-label, non-randomised, phase 2 trial at one clinic in Kambia Town, Sierra Leone. Healthy children, excluding pregnant or breastfeeding girls, who had received the Ad26.ZEBOV and MVA-BN-Filo vaccine regimen in a previous study, and were aged 1-11 years at the time of their first vaccine dose, received an intramuscular injection of Ad26.ZEBOV (5 × 1010 viral particles) and were followed up for 28 days. Primary outcomes were safety (measured by adverse events) and immunogenicity (measured by Ebola virus glycoprotein-specific IgG binding antibody geometric mean concentration) of the booster vaccine dose. Safety was assessed in all participants who received the booster vaccination; immunogenicity was assessed in all participants who received the booster vaccination, had at least one evaluable sample after the booster, and had no major protocol deviations that could have influenced the immune response. This trial is registered with ClinicalTrials.gov, NCT04711356. Between July 8 and Aug 18, 2021, 58 children were assessed for eligibility and 50 (27 aged 4-7 years and 23 aged 9-15 years) were enrolled and received an Ad26.ZEBOV booster vaccination, more than 3 years after receiving dose one of the Ad26.ZEBOV and MVA-BN-Filo vaccine regimen. The booster was well tolerated. The most common solicited local adverse event during the 7 days after vaccination was injection site pain, reported in 18 (36%, 95% CI 23-51) of 50 participants. The most common solicited systemic adverse event during the 7 days after vaccination was headache, reported in 11 (22%, 12-36) of 50 participants. Malaria was the most common unsolicited adverse event during the 28 days after vaccination, reported in 25 (50%, 36-64) of 50 participants. No serious adverse events were observed during the study period. 7 days after vaccination, the Ebola virus glycoprotein-specific IgG binding antibody geometric mean concentration was 28 561 ELISA units per mL (95% CI 20 255-40 272), which was 44 times higher than the geometric mean concentration before the booster dose. 21 days after vaccination, the geometric mean concentration reached 64 690 ELISA units per mL (95% CI 48 356-86 541), which was 101 times higher than the geometric mean concentration before the booster dose. A booster dose of Ad26.ZEBOV in children who had received the two-dose Ad26.ZEBOV and MVA-BN-Filo vaccine regimen more than 3 years earlier was well tolerated and induced a rapid and robust increase in binding antibodies against Ebola virus. These findings could inform Ebola vaccination strategies in paediatric populations. Innovative Medicines Initiative 2 Joint Undertaking. For the French translation of the abstract see Supplementary Materials section.

Immunogenicity of rVSVΔG-ZEBOV-GP Ebola vaccine (ERVEBO®) in African clinical trial participants by age, sex, and baseline GP-ELISA titer: A post hoc analysis of three Phase 2/3 trials

BackgroundERVEBO®, a live recombinant vesicular stomatitis virus (VSV) vaccine containing the Zaire ebolavirus glycoprotein (GP) in place of the VSV GP (rVSVΔG-ZEBOV-GP), was advanced through clinical development by Merck & Co., Inc., Rahway, NJ, USA in collaboration with multiple partners to prevent Ebola virus disease (EVD) and has been approved for human use in several countries. MethodsWe evaluated data from three Phase 2/3 clinical trials conducted in Liberia (PREVAIL), Guinea (FLW), and Sierra Leone (STRIVE) during the 2013–2016 West African EVD outbreak to assess immune responses using validated assays. We performed a post hoc analysis of the association of vaccine response with sex, age (18–50 yrs & >50 yrs), and baseline (BL) GP-enzyme-linked immunosorbent assay (ELISA) titer (<200 & ≥200 EU/mL), including individual study (PREVAIL, FLW, or STRIVE) data and pooled data from all 3 studies. The endpoints were total IgG antibody response (EU/mL) measured by the GP-ELISA and neutralizing antibody response measured by the plaque reduction neutralization test (PRNT) to rVSVΔG-ZEBOV-GP at Days 28, 180, and 365 postvaccination. ResultsIn the overall pooled population, in all subgroups, and in each trial independently, GP-ELISA and PRNT geometric mean titers increased from BL, generally peaking at Day 28 and persisting through Day 365. Immune responses were greater in women and participants with BL GP-ELISA ≥ 200 EU/mL, but did not differ across age groups. ConclusionThese data demonstrate that rVSVΔG-ZEBOV-GP elicits a robust and durable immune response through 12 months postvaccination in participants regardless of age, sex, or BL GP-ELISA titer. The higher immune responses observed in women and participants with pre-existing immunity are consistent with those described previously and for other vaccines.Trials were registered as follows: PREVAIL: ClinicalTrials.gov NCT02344407; FLW: Pan African Clinical Trials Registry PACTR201503001057193; STRIVE: ClinicalTrials.gov NCT02378753. Protocols V920-009, 011, and 018.

Model-based evaluation of the impact of prophylactic vaccination applied to Ebola epidemics in Sierra Leone and Democratic Republic of Congo

BackgroundProtection by preventive Ebola vaccines has been demonstrated in clinical trials, but a complete picture of real-world effectiveness is lacking. Our previous study modeling the impact of preventively vaccinating healthcare workers (HCW) alone or with a proportion of the general population (GP) estimated significant reductions in incidence and mortality. The model assumed 100% vaccine efficacy, which is unlikely in the real world. We enhanced this model to account for lower vaccine efficacy and to factor in reduced infectiousness and lower case fatality rate in vaccinated individuals with breakthrough infections.MethodsThe previous model was enhanced to still permit a risk, although lower, for vaccinated individuals to become infected. The enhanced model, calibrated with data from epidemics in Sierra Leone (SL) and North Kivu, Democratic Republic of the Congo, helped evaluate the impact of preventive Ebola vaccination in different scenarios based on different vaccine efficacy rates (90% and 30% reductions in infection risk in the base and conservative scenarios, respectively; additionally, both scenarios with 50% reductions in infectiousness and mortality) and vaccination coverage among HCWs (30%, 90%) and GP (0%, 5%, and 10%).ResultsThe base scenario estimated that, depending upon the proportions of vaccinated HCWs and GP, 33–85% of cases and 34–87% of deaths during the 2014 SL epidemic and 42–89% of cases and 41–89% of deaths during the 2018 North Kivu epidemic would be averted versus no vaccination. Corresponding estimates for the conservative scenario were: 23–74% of cases and 23–77% of deaths averted during the SL epidemic and 31–80% of both cases and deaths averted during the North Kivu epidemic.ConclusionsPreventive vaccination targeting HCW alone or with GP may significantly reduce the size and mortality of an EVD outbreak, even with modest efficacy and coverage. Vaccines may also confer additional benefits through reduced infectiousness and mortality in breakthrough cases.

Lessons Learned from the Development and Roll-Out of the rVSVΔG-ZEBOV-GP Zaire ebolavirus Vaccine to Inform Marburg Virus and Sudan ebolavirus Vaccines.

This review describes key aspects of the development of the rVSVΔG-ZEBOV-GP Ebola vaccine and key activities which are continuing to further expand our knowledge of the product. Extensive partnerships and innovative approaches were used to address the various challenges encountered during this process. The rVSVΔG-ZEBOV-GP Ebola vaccine was initially approved by the European Medicines Agency and prequalified by the World Health Organization in November 2019. It was approved by the United States Food and Drug Administration in December 2019 and approved in five African countries within 90 days of prequalification. The development resulted in the first stockpile of a registered Ebola vaccine that is available to support outbreak response. This also provides insights into how the example of rVSVΔG-ZEBOV-GP can inform the development of vaccines for Sudan ebolavirus, Marburg virus, and other emerging epidemic diseases in terms of the types of approaches and data needed to support product registration, availability, and the use of a filovirus vaccine.

Prevalence of malaria and helminth infections in rural communities in northern Sierra Leone, a baseline study to inform Ebola vaccine study protocols.

Recurrent parasitic infections may influence the immune response to vaccines. In the Partnership for Research on Ebola VACcinations extended follow-UP and clinical research capacity build-UP (PREVAC-UP) study being undertaken in Mambolo, northern Sierra Leone, participants are being followed up to assess the potential impact of exposure to malaria and/or helminth infections on long-term immune response to two Ebola vaccines. To support the development of the assays that will be used in this evaluation, a parasitological survey was conducted in Mambolo between November 2019 and February 2020. Healthy individuals aged ≥1 year who were resident in Mambolo Chiefdom were selected using a stratified sampling approach and questionnaires were administered to explore their sociodemographic characteristics. Microscopy was used to detect malaria parasites, intestinal helminths and urinary schistosome infections. Rapid blood tests were used to detect infections with Onchocerca volvulus and Wuchereria bancrofti. We estimated the overall prevalence of these infections and used adjusted logistic regression models to explore risk factors for malaria and hookworm infection. Eight hundred and fifteen (815) residents, 50.9% of whom were female were surveyed. Overall, 309 (39.1%) of 791 persons tested for malaria had a positive blood slide; Plasmodium falciparum was the dominant species. Helminth infection was detected in 122 (15.0%) of 815 stool samples including three mixed infections. The helminth infections comprised 102 (12.5%) cases of hookworm, 11 (1.3%) cases of Trichuris trichiura, 10 (1.2%) cases of Schistosoma mansoni and two (0.2%) cases of Ascaris lumbricoides. Being male (OR = 2.01, 95% CI 1.15-3.50) and residing in a non-riverine community (OR = 4.02, 95%CI 2.32-6.98) were the factors associated with hookworm infection. Onchocerca volvulus and Wuchereria bancrofti infections were found in 3.3% and 0.4% of participants respectively. Malaria and hookworm are the most prevalent parasite infections and those most likely to influence long-term immune response to Ebola vaccines among the trial participants.

“Are You Sure It’s Not the Corona Vaccine?” An Ebola Vaccine Trial During COVID-19 in DRC

ABSTRACT The COVID-19 pandemic began as an Ebola epidemic was unfolding in the Democratic Republic of the Congo. In this article, we examine how COVID-19 influenced experiences of an Ebola vaccine trial and attitudes towards medical research in Goma. First, critical debates about vaccine research became a forum in which to contest ineffective local governance and global inequality. Second, discussions about new COVID-19 therapeutics reignited critique of Western biomedical colonialism. Third, rumors were made powerful through everyday observations of the unexpected adaption of Ebola trial procedures in the pandemic. This illustrates the difficulties of maintaining participants’ trust, when circumstances dictate protocol alterations mid-trial.

Monitoring of Adverse Events in Recipients of the 2-Dose Ebola Vaccine Regimen of Ad26.ZEBOV Followed by MVA-BN-Filo in the UMURINZI Ebola Vaccination Campaign.

From 2019 to 2021, Rwandan residents of the border with the Democratic Republic of the Congo were offered the Ad26.ZEBOV (adenovirus type 26 vector vaccine encoding Ebola virus glycoprotein) and MVA-BN-Filo (modified vaccinia virus Ankara vector vaccine, encoding glycoproteins from Ebola, Sudan, Marburg, and nucleoprotein from Tai Forest viruses) Ebola vaccine regimen. Nonpregnant persons aged ≥2 years were eligible. Unsolicited adverse events (UAEs) were reported through phone calls or visits, and serious adverse events (SAEs) were recorded per International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use guidelines. Following Ad26.ZEBOV, UAEs were reported by 0.68% of 216 113 vaccinees and were more common in younger children (aged 2-8 years, 1.2%) compared with older children (aged 9-17 years, 0.4%) and adults (aged ≥18 years, 0.7%). Fever and headache were the most reported symptoms. All 17 SAEs related to vaccine were in children aged 2-8 years (10 postvaccination febrile convulsions ± gastroenteritis and 7 fever and/or gastroenteritis). The incidence of febrile seizures was 8 of 26 062 (0.031%) prior to initiation of routine acetaminophen in December 2020 and 2 of 15 897 (0.013%) thereafter. Nonobstetric SAEs were similar in males and females. All 20 deaths were unrelated to vaccination. Young girls and adult women with UAEs were less likely to receive the second dose than those without UAEs. Seven unrelated SAEs occurred in 203 267 MVA-BN-Filo recipients. Postvaccination febrile convulsions in young children were rare but not previously described after Ad26.ZEBOV and were reduced with routine acetaminophen. The regimen was otherwise safe and well-tolerated.

Two-dose Ebola vaccine regimen generally well tolerated

Two-dose Ebola vaccine regimen generally well tolerated

Recombinant vesicular stomatitis vaccine against Nipah virus has a favorable safety profile: Model for assessment of live vaccines with neurotropic potential.

Nipah virus (NiV) disease is a bat-borne zoonosis responsible for outbreaks with high lethality and is a priority for vaccine development. With funding from the Coalition of Epidemic Preparedness Innovations (CEPI), we are developing a chimeric vaccine (PHV02) composed of recombinant vesicular stomatitis virus (VSV) expressing the envelope glycoproteins of both Ebola virus (EBOV) and NiV. The EBOV glycoprotein (GP) mediates fusion and viral entry and the NiV attachment glycoprotein (G) is a ligand for cell receptors, and stimulates neutralizing antibody, the putative mediator of protection against NiV. PHV02 is identical in construction to the registered Ebola vaccine (Ervebo) with the addition of the NiV G gene. NiV ephrin B2 and B3 receptors are expressed on neural cells and the wild-type NiV is neurotropic and causes encephalitis in affected patients. It was therefore important to assess whether the NiV G alters tropism of the rVSV vector and serves as a virulence factor. PHV02 was fully attenuated in adult hamsters inoculated by the intramuscular (IM) route, whereas parental wild-type VSV was 100% lethal. Two rodent models (mice, hamsters) were infected by the intracerebral (IC) route with graded doses of PHV02. Comparator active controls in various experiments included rVSV-EBOV (representative of Ebola vaccine) and yellow fever (YF) 17DD commercial vaccine. These studies showed PHV02 to be more neurovirulent than both rVSV-EBOV and YF 17DD in infant animals. PHV02 was lethal for adult hamsters inoculated IC but not for adult mice. In contrast YF 17DD retained virulence for adult mice inoculated IC but was not virulent for adult hamsters. Because of the inconsistency of neurovirulence patterns in the rodent models, a monkey neurovirulence test (MNVT) was performed, using YF 17DD as the active comparator because it has a well-established profile of quantifiable microscopic changes in brain centers and a known reporting rate of neurotropic adverse events in humans. In the MNVT PHV02 was significantly less neurovirulent than the YF 17DD vaccine reference control, indicating that the vaccine will have an acceptable safety profile for humans. The findings are important because they illustrate the complexities of phenotypic assessment of novel viral vectors with tissue tropisms determined by transgenic proteins, and because it is unprecedented to use a heterologous comparator virus (YF vaccine) in a regulatory-enabling study. This approach may have value in future studies of other novel viral vectors.

EE58 Value-Based Pricing of an Ebola Vaccine in Resource-Constrained Countries Based on Cost-Effectiveness Analysis

Pricing, affordability, and access are important deliberations around infectious disease interventions. Determining a fair price that not only incentivizes development but ensures value and access for patients is critical given the increasing global health crisis. Using ebola virus disease (EVD) as exemplar, we aim to elucidate the estimation of a value-based price (VBP) for a vaccine package and to consider how the price compares across selected countries that have experienced EVD outbreaks.

Safety, reactogenicity, and immunogenicity of a 2-dose Ebola vaccine regimen of Ad26.ZEBOV followed by MVA-BN-Filo in healthy adult pregnant women: study protocol for a phase 3 open-label randomized controlled trial

BackgroundRisks to mother and fetus following Ebola virus infection are very high. Evaluation of safety and immunogenicity of non-replicating Ebola vaccine candidates is a priority for use in pregnant women. This is the protocol for a randomized, open-label, single-center phase 3 clinical trial of the safety, reactogenicity, and immunogenicity of the 2-dose Ebola vaccine regimen in healthy adult pregnant women. This 2-dose regimen has been shown to be safe, judged effective, and approved in non-pregnant populations.MethodsA total of 2000 adult (≥ 18 years of age) pregnant women will be enrolled from antenatal care facilities in Western Rwanda and randomized (1:1) to receive the 2-dose Ebola vaccine regimen (Ad26.ZEBOV, MVA-BN-Filo (group A)) or control (unvaccinated pregnant women (group B)). The primary objectives are to (1) assess adverse maternal/fetal outcomes in randomized pregnant women up to 1.5 months after delivery and (2) assess adverse neonatal/infant outcomes in neonates/infants born to randomized women up to 3.5 months after birth. The frequency and relatedness of all serious adverse events in women and newborns from randomization or birth, respectively, until study end will be reported. The reactogenicity and unsolicited adverse events of the 2-dose Ebola vaccine regimen in all vaccinated pregnant women (group A) will be reported. We will also assess the immunogenicity of the 2-dose Ebola vaccine regimen in 150 pregnant women who are anticipated to receive both vaccine doses within the course of their pregnancy (a subset of the 1000 pregnant vaccinated women from group A) compared to 150 non-pregnant women vaccinated after delivery (a subset of group B). The persistence of maternal antibodies in 75 infants born to women from the group A subset will be assessed. Exploratory analyses include assessment of acceptability of the 2-dose Ebola vaccine regimen among group A and assessment of maternal antibodies in breast milk in 50 women from group A and 10 controls (women from group B prior to vaccination).DiscussionThis study is intended to support a label variation to relax restrictions on use in pregnant women, a vulnerable population with high medical need.Trial registrationClinicaltrials.gov NCT04556526. September 21, 2020.

NK Cell Subset Redistribution and Antibody Dependent Activation after Ebola Vaccination in Africans.

Natural killer cells play an important role in the control of viral infections both by regulating acquired immune responses and as potent innate or antibody-mediated cytotoxic effector cells. NK cells have been implicated in control of Ebola virus infections and our previous studies in European trial participants have demonstrated durable activation, proliferation and antibody-dependent NK cell activation after heterologous two-dose Ebola vaccination with adenovirus type 26.ZEBOV followed by modified vaccinia Ankara-BN-Filo. Regional variation in immunity and environmental exposure to pathogens, in particular human cytomegalovirus, have profound impacts on NK cell functional capacity. We therefore assessed the NK cell phenotype and function in African trial participants with universal exposure to HCMV. We demonstrate a significant redistribution of NK cell subsets after vaccine dose two, involving the enrichment of less differentiated CD56dimCD57− and CD56dimFcεR1γ+ (canonical) cells and the increased proliferation of these subsets. Sera taken after vaccine dose two support robust antibody-dependent NK cell activation in a standard NK cell readout; these responses correlate strongly with the concentration of anti-Ebola glycoprotein specific antibodies. These sera also promote comparable IFN-γ production in autologous NK cells taken at baseline and post-vaccine dose two. However, degranulation responses of post-vaccination NK cells were reduced compared to baseline NK cells and these effects could not be directly attributed to alterations in NK cell phenotype after vaccination. These studies demonstrate consistent changes in NK cell phenotypic composition and robust antibody-dependent NK cell function and reveal novel characteristics of these responses after heterologous two dose Ebola vaccination in African individuals.

Setting-up an Ebola vaccine trial in a remote area of the Democratic Republic of the Congo: Challenges, mitigations, and lessons learned

Since the largest Ebola outbreak in West Africa (2013–2016) highlighted the potential threat of the Ebola virus to the world, several vaccines have been under development by different pharmaceutical companies. To obtain vaccine licensure, vaccine trials assessing the safety, immunogenicity and efficacy of new vaccines among different populations (e.g. different in age, gender, race, and ethnicity) play a crucial role. However, while this deadly disease mainly affects Central and West Africa, clinical trial regulations are becoming increasingly complex and consequently more expensive, influencing the affected low- and middle-income countries (LMICs) in performing high quality clinical trials. Consequently, the completion of such trials in LMICs takes more time and vaccines and drugs take longer to be licensed. To overcome some of the obstacles faced, the EBOVAC3 consortium, funded by the European Union’s Innovative Medicines Initiative and the Coalition for Epidemic Preparedness Innovations, enabled high quality vaccine trials in Central and West Africa through extensive North-South collaborations. In this article, the encountered challenges, mitigations, recommendations and lessons learned from setting-up an Ebola vaccine trial in a remote area of the Democratic Republic of Congo are presented. These challenges are grouped into eight categories: (1) Regulatory, political and ethical, (2) Trial documents, (3) International collaborations, (4) Local trial staff, (5) Community engagement and sensitization, (6) Logistics, (7) Remoteness and climate conditions, (8) Financial. By sharing the encountered challenges, implemented mitigations and lessons learned for each of these categories, we hope to prepare and inform other researchers aspiring a well-functioning clinical trial unit in similar remote settings in LMICs. ClinicalTrials.gov identifier: NCT04186000.