The First Randomized Controlled Trial on Vitamin D and Covid-19
> open label, double-masked clinical trial<p>Aren't "open label" and "double-masked" contradictory?<p>"An open-label trial, or open trial, is a type of clinical trial in which information is not withheld from trial participants. In particular, both the researchers and participants know which treatment is being administered." (Wikipedia)<p>"Double-Masked Study. A type of clinical trial in which neither the participants nor the research team know which treatment a specific participant is receiving." (NIH)