Key criteria for the ethical acceptability of controlled human infection studies during public health emergencies

Overview

Controlled human infection studies (CHIS) involve the intentional infection of volunteers with pathogens, including those that cause epidemics or pandemics. Such studies can inform responses to public health emergencies. For example, SARS-CoV-2 CHIS commenced during the COVID19 pandemic, providing data on coronavirus infection and the accuracy of diagnostic testing methods.  Zika virus CHIS were proposed during the 2015-16 Zika emergency but were not conducted until after the epidemic waned, when standard vaccine field trials were no longer feasible. It is therefore likely that CHIS may be proposed during future public health emergencies, and such proposals often generate significant ethical and scientific debate

In response to the need for ethical guidance to inform policy regarding potential CHIS research programs during emergencies, WHO has developed key criteria that CHIS would need to meet to ensure that such research is conducted to the highest ethical standards in emergency contexts. This document aims to provide guidance to scientists, research ethics committees, funders, policy-makers, and regulators in deliberations regarding CHIS during emergencies by outlining key criteria that would need to be satisfied in order for such studies to be ethically acceptable.