A World Health Organization (WHO) Ad Hoc Expert Group on the Next Steps for Covid-19 Vaccine Evaluation recently recommended placebo-controlled trials (PCT) of Covid-19 vaccines. PCTs are ethically acceptable when there is no proven effective and safe treatment for a certain condition. However, there are already some vaccines that have been approved and which have high levels of efficacy and safety. Any new vaccine under development must be tested against the most effective vaccines available. PCTs go against the participants' best interests, by putting them in a position of disadvantage while taking part in a trial, compared with people who are not in the trial and who could get vaccinated. Particularly in high-income countries, many people are getting vaccinated. This means that, following a recent trend in clinical trials, PCTs would have to be conducted in low- and middle-income countries, where there a number of advantages for drug companies, but where fatality rates of Covid-19 are, in many cases, much higher. For this and other reasons having to do with equal rights, participants in control groups should be protected with the most effective vaccines available.