Report of the WHO AG on human challenge studies

Overview

Currently, there are several types of vaccine candidates in development that are demonstrating encouraging proof of principle in terms of good safety profile and efficacy, and are being tracked by the WHO landscape, in collaboration with global partners.  In November 2020, some research groups announced that they were planning to undertake volunteer challenge studies to develop and utilize a COVID-19 challenge model. There was a need to understand the current situation in terms of questions that the investigators were going to address using their models and how closely the models comply with specific technical guidelines contained within the WHO document on COVID-19 challenge models. One specific important question was to shape information on whether or not there is or will imminently exist effective “rescue treatments”. This will impact the study design, implementation and outcome of challenge studies, for which WHO can deliver guidance.

Objectives of the meeting

• Summarizing developments since the last Advisory Group meeting;
• Having research groups with plans for challenge models present the objectives for use of their models, once established (e.g., to test an existing vaccine, test a new vaccine, explore correlates of protection against certain endpoints, assess the degree of immunity conferred by wild virus, etc.); 
• Discussing technical concerns that need to be addressed to develop a robust protocol design and plan for effective implementation and expected outcome;
• Considering the issues and impact that human challenge studies may have on acceptance and uptake of COVID-19 vaccines that are ready for roll-out;
• Discussing the potential role for human challenge studies to play in evaluating the second and third generation of COVID-19 vaccines;
• Reviewing whether there are new additions to the therapeutics armamentarium that could serve as a reliable “rescue treatment”;
• Discussing the advantages and disadvantages of using different GMP virus batches;
• Identifying areas that could be harmonized across STAGE 1 COVID-19 human challenge models;
• Discussing recommendations and next steps.