The Lancet has retracted a paper which stated that hydroxychloroquine was dangerous for people sick with Covid-19. Now it seems we do not know whether it is dangerous or not.

It appears that the paper was based on false data.

Peer reviewers usually try to check the methods and assumptions, which they can read, but they have no easy way to check the underlying data when those are not published. However, personal medical data must not be published.

Meanwhile, a large experimental study has found that hydroxychloroquine provides no benefit to people ill with Covid-19.