Propagation of SARS-CoV-2 in a Closed Cell Culture Device: Potential GMP Compatible Production Platform for Live-Attenuated Vaccine Candidates under BSL-3 Conditions?

Live-attenuated SARS-CoV-2 vaccines present themselves as a promising approach for the induction of broad mucosal immunity. However, for initial safety assessment in clinical trials, virus production requires conditions meeting Good Manufacturing Practice (GMP) standards while maintaining biosafety level 3 (BSL-3) requirements. Since facilities providing the necessary complex ventilation systems to meet both requirements are rare, we here describe a possibility to reproducibly propagate SARS-CoV-2 in the automated, closed cell culture device CliniMACS Prodigy® in a common BSL-3 laboratory. In this proof-of-concept study, we observed an approximately 300-fold amplification of SARS-CoV-2 under serum-free conditions with high lot-to-lot consistency in the infectious titers obtained. With the possibility to increase production capacity to up to 3000 doses per run, this study outlines a potential fast-track approach for the production of live-attenuated vaccine candidates based on highly pathogenic viruses under GMP-like conditions that may contribute to pandemic preparedness.

Clinical trials for accelerating pandemic vaccines

We provide a short overview of clinical trials of vaccines, with particular focus on (i) adaptive and platform trials, (ii) human challenge trials, and (iii) vaccine use optimization, especially fractional dosing. We describe their relationship with regulatory approval and review main developments during Covid-19. We review the literature on risk-benefit analyses of alternative testing approaches but find few results, suggesting need for further quantitative research. We conclude by discussing some lessons for the next pandemic, such as the need for pre-pandemic R&D and clear guidelines;improving capability to use new trial approaches;arguments for diversifying research methods;research incentives and disincentives;and the need to use risk-benefit in approving new vaccines and targeting.

The role of public involvement in the design of the first SARS-CoV-2 human challenge study during an evolving pandemic.

High quality health care research must involve patients and the public. This ensures research is important, relevant and acceptable to those it is designed to benefit. The world's first human challenge study with SARS-CoV-2 undertook detailed public involvement to inform study design despite the urgency to review and establish the study. The work was integral to the UK Research Ethics Committee review and approval of the study. Discussion with individuals from ethnic minorities within the UK population supported decision-making around the study exclusion criteria. Public review of study materials for consent processes led to the addition of new information, comparisons and visual aids to help volunteers consider the practicalities and risks involved in participating. A discussion exploring the acceptability of a human challenge study with SARS-CoV-2 taking place in the UK, given the current context of the pandemic, identified overall support for the study. Public concern for the wellbeing of trial participants, as a consequence of isolation, was identified. We outline our approach to public involvement and its impact on study design.

Risk, benefit, and social value in Covid-19 human challenge studies: pandemic decision making in historical context.

During the Covid-19 pandemic, ethicists and researchers proposed human challenge studies as a way to speed development of a vaccine that could prevent disease and end the global public health crisis. The risks to healthy volunteers of being deliberately infected with a deadly and novel pathogen were not low, but the benefits could have been immense. This essay is a history of the three major efforts to set up a challenge model and run challenge studies in 2020 and 2021. The pharmaceutical company Johnson and Johnson, the National Institutes of Health in the United States, and a private-public partnership of industry, university, and government partners in Britain all undertook preparations. The United Kingdom's consortium began their Human Challenge Programme in March of 2021.Beyond documenting each effort, the essay puts these scientific and ethical debates in dialogue with the social, epidemiological, and institutional conditions of the pandemic as well as the commercial, intellectual, and political systems in which medical research and Covid-19 challenge studies operated. It shows how different institutions understood risk, benefit, and social value depending on their specific contexts. Ultimately the example of Covid-19 challenge studies highlights the constructedness of such assessments and reveals the utility of deconstructing them retrospectively so as to better understand the interplay of medical research and research ethics with larger social systems and historical contexts.

A new day for human challenge trials?

Two years into the coronavirus disease 2019 (COVID-19) pandemic and following several hot debates, the world's first COVID-19 human challenge trial has recently been published by Killingley et al. We review its findings and explain why this particular juncture in time makes additional challenge trials for COVID-19 and for other diseases justified and important.

Human infection studies: Key considerations for challenge agent development and production.

Human infection (or challenge) studies involve the intentional administration of a pathogen (challenge agent) to volunteers. The selection, isolation, development and production of the challenge agent is one of the first steps in developing a challenge study and critical for minimising the risk to volunteers. Regulatory oversight for this production differs globally. Manufacturing agents within a Good Manufacturing Practice (GMP) facility reduces the risk of the manufacturing process by including processes such as confirming the identity of the challenge agent and ascertaining that it's pure and free from impurities. However, in some cases it's not possible or feasible to manufacture to GMP standards, for example where the challenge agent requires an intermediate vector for growth. There is lack of clear guidance on what the minimum requirements for high-quality safe manufacture outside of GMP facilities should be and here we describe the development of a considerations document for the selection and production of challenge agents to meet this need.

Public attitudes to a human challenge study with SARS-CoV-2: a mixed-methods study.

Background: Human challenge studies involve the deliberate exposure of healthy volunteers to an infectious micro-organism in a highly controlled and monitored way. They are used to understand infectious diseases and have contributed to the development of vaccines. In early 2020, the UK started exploring the feasibility of establishing a human challenge study with SARS-CoV-2. Given the significant public interest and the complexity of the potential risks and benefits, it is vital that public views are considered in the design and approval of any such study and that investigators and ethics boards remain accountable to the public. Methods: Mixed methods study comprising online surveys conducted with 2,441 UK adults and in-depth virtual focus groups with 57 UK adults during October 2020 to explore the public's attitudes to a human challenge study with SARS-CoV-2 taking place in the UK. Results: There was overall agreement across the surveys and focus groups that a human challenge study with SARS-CoV-2 should take place in the UK. Transparency of information, trust and the necessity to provide clear information on potential risks to study human challenge study participants were important. The perceived risks of taking part included the risk of developing long-term effects from COVID, impact on personal commitments and mental health implications of isolation. There were a number of practical realities to taking part that would influence a volunteer's ability to participate (e.g. Wi-Fi, access to exercise, outside space and work, family and pet commitments). Conclusions: The results identified practical considerations for teams designing human challenge studies. Recommendations were grouped: 1) messaging to potential study participants, 2) review of the protocol and organisation of the study, and 3) more broadly, making the study more inclusive and relevant. This study highlights the value of public consultation in research, particularly in fields attracting public interest and scrutiny .

The Ethics of Human Challenge Trials Using Emerging Severe Acute Respiratory Syndrome 2 Variants.

The world's first coronavirus disease 2019 human challenge trial using the D614G strain of severe acute respiratory syndrome 2 (SARS-CoV-2) is underway in the United Kingdom. The Wellcome Trust is funding challenge stock preparation of the Beta and Delta variant for a follow-up human challenge trial, and researchers at hVIVO are considering conducting these trials. However, little has been written thus far about the ethical justifiability of human challenge trials with SARS-CoV-2 variants of concern. We explore 2 specific characteristics of some variants that may initially be thought to make such trials unethical and conclude that SARS-CoV-2 variant challenge trials can remain ethical.

Ethics review of COVID-19 human challenge studies: A joint HRA/WHO workshop.

This report of a joint World Health Organization (WHO) and United Kingdom (UK) Health Research Authority (HRA) workshop discusses the ethics review of the first COVID-19 human challenge studies, undertaken in the midst of the pandemic. It reviews the early efforts of international and national institutions to define the ethical standards required for COVID-19 human challenge studies and create the frameworks to ensure rigorous and timely review of these studies. This report evaluates the utility of the WHO's international guidance document Key criteria for the ethical acceptability of COVID-19 human challenge studies (WHO Key Criteria) as a practical resource for the ethics review of COVID-19 human challenge studies. It also assesses the UK HRA's approach to these complex ethics reviews, including the formation of a Specialist Ad-Hoc Research Ethics Committee (REC) for COVID-19 Human Challenge Studies to review all current and future COVID-19 human challenge studies. In addition, the report outlines the reflections of REC members and researchers regarding the ethics review process of the first COVID-19 human challenge studies. Finally, it considers the potential ongoing scientific justification for COVID-19 human challenge studies, particularly in relation to next-generation vaccines and optimisation of vaccination schedules. Overall, there was broad agreement that the WHO Key Criteria represented an international consensus document that played a powerful role in setting norms and delineating the necessary conditions for the ethical acceptability of COVID-19 human challenge studies. Workshop members suggested that the WHO Key Criteria could be practically implemented to support researchers and ethics reviewers, including in the training of ethics committee members. In future, a wider audience may be engaged by the original document and potential additional materials, informed by the experiences of those involved in the first COVID-19 human challenge studies outlined in this document.

Innovative vaccine approaches-a Keystone Symposia report.

The rapid development of COVID-19 vaccines was the result of decades of research to establish flexible vaccine platforms and understand pathogens with pandemic potential, as well as several novel changes to the vaccine discovery and development processes that partnered industry and governments. And while vaccines offer the potential to drastically improve global health, low-and-middle-income countries around the world often experience reduced access to vaccines and reduced vaccine efficacy. Addressing these issues will require novel vaccine approaches and platforms, deeper insight how vaccines mediate protection, and innovative trial designs and models. On June 28-30, 2021, experts in vaccine research, development, manufacturing, and deployment met virtually for the Keystone eSymposium "Innovative Vaccine Approaches" to discuss advances in vaccine research and development.

Ethical Challenges in Novel Coronavirus Pneumonia Vaccine as Well as New Drug Research and Development

To review systematically the progress of all domestic and foreign clinical trials since the emergence of the COVID-19 epidemic and the overview of human challenge study (HCS) in the past year, grasp relevant information of ethical review, and explores the feasibility of human challenge study and provide references for stake holders. Based on the Chinese Clinical Trial Registration Center and clinical trial. gov, clinical trials that were consistent with COVID-19 was searched, and the deadline was June 11, 2020.Basic information was extracted and the number of trials was selected from the research type, clinical stage, recruitment status, and ethical passing status. Literature search was conducted based on Pubmed between January 1, 2019 and June 11, 2020.According to the included literature, basic information was extracted and opinions were reported on HCS. 638 and 1935 clinical trials were carried out at home and abroad respectively, of which the number of clinical trials carried out in Hubei reached 323. China and the United States conducted more interventional trials, and the United States had the most clinical trials entered in Phase II, there were a total of 142. Most of the clinical trials were in the stage of recruiting research subjects. In addition, a total of 539 clinical trials in China had passed ethical approval. A total of 5 documents were included in the Human Challenge Study, four maintained a positive attitude towards HCS and put forward corresponding thinking about ethical review. Under the COVID-19, clinical trials for new drugs and new coronavirus vaccines have rapidly increased, which puts forward higher requirements for the progress of ethical review. In the face of such public health emergencies and special research, it is urgent to establish a sound ethical review system and an ethical review system, as well as to construct an ethical model for special research. © 2021, Editorial Board of Pharmaceutical Biotechnology. All right reserved.

Assessment of Risks Associated With Severe Acute Respiratory Syndrome Coronavirus 2 Experimental Human Infection Studies.

Controlled human infection (CHI) models for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been proposed as a tool to accelerate the development of vaccines and drugs. Such models carry inherent risks. Participants may develop severe disease or complications after deliberate infection. Prolonged isolation may negatively impact their well-being. Through secondary infection of study personnel or participant household contacts, the experimental virus strain may cause a community outbreak. We identified risks associated with such a SARS-CoV-2 CHI model and assessed their likelihood and impact and propose strategies that mitigate these risks. In this report, we show that risks can be minimized with proper risk mitigation strategies; the residual risk, however, should be weighed carefully against the scientific and social values of such a CHI model.

Human Challenge Studies for Vaccine Development : Regulatory Aspects of Human Challenge Studies.

The traditional regulatory pathway for the evaluation of new vaccine candidates generally proceeds from preclinical through three successive phases of human trials, and the demonstration of efficacy is usually done through randomized-controlled clinical trials. However, human challenge trials or controlled human infection models have been used in vaccine clinical development to generate supportive data for establishment of correlates of protection, supportive data for licensure, as well as licensure in the case of Vaxchora® by the US FDA. Despite this, there are no codified regulations from national regulatory authorities (NRAs) that specifically address HCTs, nor guidance related to standardization of approaches to HCTs among regulators. NRAs may agree that HCTs are innovative, promising tools to accelerate vaccine development; however, a strong benefit/risk assessment is needed to ensure the safety of study participants. Lastly, it is important to consider the regulatory framework in which the human challenge trial may be conducted.

Justifying the risks of COVID-19 challenge trials: The analogy with organ donation.

In the beginning of the COVID pandemic, researchers and bioethicists called for human challenge trials to hasten the development of a vaccine for COVID. However, the fact that we lacked a specific, highly effective treatment for COVID led many to argue that a COVID challenge trial would be unethical and we ought to pursue traditional phase III testing instead. These ethical objections to challenge trials may have slowed the progress of a COVID vaccine, so it is important to evaluate their merit. One common way of doing so is to make an analogy to other social practices that are relevantly similar and which we currently sanction. We submit that non-directed live organ donation (NDLOD) is a promising analogy. After arguing that the risks to volunteers for each activity appear similar, we explore potential disanalogies that would undermine the comparison. We note that there are differences in both the kind and certainty of benefit secured by NDLOD compared to challenge trials. We conclude these differences are insufficient to make NDLOD permissible and challenge trials impermissible. Ultimately, if we think the risks associated with NDLOD are ethically permissible, then we should think the same of the risks associated with COVID challenge trials.

Perspectives of research ethics committee members on human challenge studies in the development of vaccines against COVID-19: a mixed methods study.

BACKGROUND: Vaccines are considered the most effective protection against the coronavirus disease 2019 (COVID-19). Human Challenge Studies can help to shorten the development process of vaccines. The reviewers' opinions from research ethics committees (REC) play an essential gate-keeping role in determining whether a clinical trial can be conducted or not. METHODS: A convergent mixed-methods study was conducted in a leading general hospital in China. A total of 58 REC members from the institution were invited to participate in an online questionnaire survey. According to the result of the quantitative survey, 15 of these REC members were purposefully selected to participate in qualitative interviews further. Quantitative data were analyzed using descriptive statistical techniques, and thematic analysis was used to analyze the qualitative data. Findings from the quantitative and qualitative analyses were synthesized to deeply illustrate the attitudes, views, and suggestions of REC members on human challenge studies to develop COVID-19 vaccination. RESULTS: The response rate of the online questionnaire was 62% (36/58), and 15 of the respondents were interviewed. All participants deemed that the human challenge study should provide compensation to its participants and that sufficiently informed consent is necessary. The human challenge study was disagreed with by 38.9% of participants. The key points of concern raised were representativeness and fairness of participant selection, benefit, and risk, vulnerable groups, compensation to participants, informed consent, and general view on human challenge studies. CONCLUSIONS: Human challenge studies helped accelerate the development of vaccines for disease control to a certain extent, but the bottom line of medical ethics should not have been broken. At any time, the rights and interests of research participants should come first.

Exploring Risks of Human Challenge Trials For COVID-19.

Human challenge trials (HCTs) are a potential method to accelerate development of vaccines and therapeutics. However, HCTs for COVID-19 pose ethical and practical challenges, in part due to the unclear and developing risks. In this article , we introduce an interactive model for exploring some risks of a severe acute respiratory syndrome coronavirus-2 (SARS-COV-2) dosing study, a prerequisite for any COVID-19 challenge trials. The risk estimates we use are based on a Bayesian evidence synthesis model which can incorporate new data on infection fatality risks (IFRs) to patients, and infer rates of hospitalization. The model estimates individual risk, which we then extrapolate to overall mortality and hospitalization risk in a dosing study. We provide a web tool to explore risk under different study designs. Based on the Bayesian model, IFR for someone between 20 and 30 years of age is 15.1 in 100,000, with a 95% uncertainty interval from 11.8 to 19.2, while risk of hospitalization is 130 per 100,000 (100-160). However, risk will be reduced in an HCT via screening for comorbidities, selecting lower-risk population, and providing treatment. Accounting for this with stronger assumptions, we project the fatality risk to be as low as 2.5 per 100,000 (1.6-3.9) and the hospitalization risk to be 22.0 per 100,000 (14.0-33.7). We therefore find a 50-person dosing trial has a 99.74% (99.8-99.9%) chance of no fatalities, and a 98.9% (98.3-99.3%) probability of no cases requiring hospitalization.

SARS-CoV-2 Human Challenge Trials: Rethinking the Recruitment of Healthy Young Adults First.

In the midst of the ongoing Covid-19 pandemic, researchers across the globe are still working to develop effective vaccines. To expedite this process even further, human challenge trials have been proposed by the World Health Organization (WHO) as an alternative to conventional approaches. In such trials, healthy volunteers are deliberately infected with the pathogen of interest, enabling scientists to study the infection process and facilitate further research on treatments or prophylactics, including vaccines. While human challenge trials would offer a collective benefit to society, minimizing the risks is always difficult. Ethical controversy thus inevitably surrounds these trials. Typically, healthy young adults are recruited to serve as the first candidate subjects for human challenge trials because they are generally considered to represent a low-risk population. Here, we present three reasons for doubt about this healthy-young-adults-first criterion and give justification for also recruiting healthy older adults (or not-young adults), meaning those over 30 years of age, to participate in such trials for SARS-CoV-2.

Prioritizing second-generation SARS-CoV-2 vaccines through low-dosage challenge studies.

The design of human challenge studies balances scientific validity, efficiency and study safety. This Perspective explores some advantages and disadvantages of 'low-dosage' challenge studies, in the setting of testing second-generation vaccines against COVID-19. Compared with a conventional vaccine challenge, a low-dosage vaccine challenge would be more likely to start, and start earlier. A low-dosage challenge would also be less likely to rule out a vaccine candidate that would have potentially been effective, particularly in certain target uses. A key ethical advantage of a low-dosage challenge over a conventional challenge is that both it and its dose escalation process are safer for each participant. Low-dosage studies would require larger numbers of participants than conventional challenges, but this and other potential disadvantages are less serious than they may initially appear. Overall, low-dosage challenges should be considered for certain roles such as prioritizing between second-generation vaccines against COVID-19.