Viewpoint of a WHO Advisory Group Tasked to Consider Establishing a Closely-monitored Challenge Model of Coronavirus Disease 2019 (COVID-19) in Healthy Volunteers

Abstract

WHO 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 coronavirus 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 step..