New placebo-controlled Covid-19 vaccine trials are ethically questionable; it's now about comparative effectiveness and availability of registered vaccines

[...]that a number of vaccines against Covid-19 are approved by internationally authoritative regulators for use in a variety of target groups, an important ethical issue is whether investigators of new candidate vaccines should still assign participants to placebo groups, thereby withholding them the protection that already available vaccines can offer [1]. [...]the international community should provide resources to deploy highly effective vaccines worldwide as quickly as possible to combat the pandemic successfully and minimize the time for potentially more dangerous virus mutants to occur. [...]with more concerted action on a global scale and extensive procurement, significant price reductions, as justified given the enormous amount of public money invested, can be better achieved. [...]the international medical research community must make clear that the time has come to no longer allow new placebo-controlled Covid-19 vaccine trials, and that the research focus should shift towards investigating comparative effectiveness of new candidate vaccines versus already registered ones.