HO convened an Advisory Group (AG) to consider the feasibility, potential value, and limitations of establishing a closely?monitored challenge model of experimental severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and coro?navirus disease 2019 (COVID-19) in healthy adult volunteers. The AG included experts in design, establishment, and performance of challenges. This report summarizes issues that render a COVID-19 model daunting to establish (the potential of SARS-CoV-2 to cause severe/fatal illness, its high transmissibility, and lack of a “rescue treatment” to prevent progression from mild/moderate to severe clinical illness) and it proffers prudent strategies for stepwise model development, challenge virus selection, guidelines for manufacturing challenge doses, and ways to contain SARS-CoV-2 and prevent transmission to household/community contacts. A COVID-19 model could demonstrate protection against virus shedding and/or illness induced by prior SARS-CoV-2 challenge or vaccination. A limitation of the model is that vaccine efficacy in experimentally challenged healthy young adults cannot per se be extrapolated to predict efficacy in elderly/high-risk adults.
This article discusses the science behind herd immunity and the important role that vaccinations play in ensuring that herd immunity can be achieved.
Request for proposals : Regulatory support consultancy for the use of human infection studies to accelerate coronavirus vaccine licensureby Editorial team
This article, published in The Lancet Infectious Diseases, presents the ethical issues associated with human challenge studies and COVID-19.
The third coronavirus outbreak in the past 20 years, the SARS-CoV-2 pandemic has caused unprecedented morbidity, mortality, and economic disruption. Safe, effective, and deployable SARS-CoV-2 vaccines are urgently needed to mitigate the consequences of the pandemic and protect from future outbreaks. The accelerated response to Covid-19 includes investments in preclinical and clinical testing and manu- facture of multiple vaccine candidates, with efficacy trials in the United States anticipated to start in July 2020.