evidence: Placebo use and unblinding in COVID-19 vaccine trials: recommendations of a WHO Expert Working Group [...] From a scientific standpoint, it is important for the clinical trials of vaccines granted an EUD to continue to their completion. But the provision of a candidate vaccine under an EUD to millions of people raises urgent questions about the continuation of the control-group arm of these and other trials, and whether trial blinding is still warranted. Current research-ethics guidance documents7,8,9 were not drafted with emergency-use deployment in mind. Given such dilemmas and guidance gaps, the WHO ACT-Accelerator Ethics & Governance Working Group (ACT: Access to COVID-19 Tools; called ‘Working Group’ here) has developed a policy brief to guide ethical decision-making in these circumstances: ‘Emergency Use Designation of COVID-19 candidate vaccines: Ethical considerations for current and future COVID-19 placebo-controlled vaccine trials and trial unblinding’10. [...] World Health Organization. https://apps.who.int/iris/bitstream/handle/10665/337940/WHO-2019-nCoV-Policy_Brief-EUD_placebo-controlled_vaccine_trials-2020.1-eng.pdf?sequence=1&isAllowed=y (18 December 2020).