It is fair to say that nothing is more pressing in today’s world than bringing an end to the Covid-19 pandemic. Or to be more precise, if not an end, then the quickest and most effective reduction of mortality and morbidity from the disease in every country where infections exist. The forthcoming theme issue of IJME explores a long-standing ethical concern in research with human beings, focused mainly on a question posed about vaccine research for prevention of Covid-19. Contributors from six continents address the question: In what circumstances – if any ‒ is it ethically acceptable to use a research design in which the control group in a randomised, controlled trial (RCT) receives a placebo instead of a vaccine already approved for emergency use by regulatory bodies? That ethical question is not new.