(CNN) The 2020 Summer Olympics are finally underway in Tokyo.
Competition began Wednesday, more than a year after the original start date. The Games were delayed due to the pandemic, but with Covid-19 still spreading unchecked in Japan, organizers have been forced to take unprecedented steps to keep competitors and the public safe.
Athletes who contracted coronavirus have seen their Olympic dreams dashed.
Some tested positive in Japan, some before coming.
These are the athletes we know who have publicly dropped out due to Covid-19 health and safety protocols.