A vaccine trial with a conventional challenge design can be very fast once it starts, but it requires a long prior process, in part, to grow and standardize challenge virus in the laboratory. This detracts somewhat from its overall promise for accelerated efficacy testing of SARS-CoV-2 vaccine candidates, and from the ability of developing countries and small companies to conduct it.
We set out to identify a challenge design that avoids this part of the long prior process.
Literature in trial design (including a proof of concept flu challenge trial by B. Killingley et al), vaccinology, medical ethics, and various aspects of COVID response.
A challenge design with deliberate natural viral exposure avoids the need to grow culture. This new design is described and compared both to a conventional challenge design and to a conventional phase III field trial. In comparison, the propsed design has ethical, scientific, and feasibility strengths.
The proposed new design should be considered for future vaccine trials.

Copyright © 2020. Published by Elsevier Ltd.

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