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Hydroxychloroquine – an old anti-malarial drug that is today more commonly used to treat lupus – has become another partisan political wedge issue in the US: conservative politicians and media figures have hyped studies that support the theory that the drug is a potential treatment.

And on Wednesday, Rick Bright, the head of a US government agency charged with investing in treatments and responses for pandemics, said he was forced out of his job over his resistance to the administration’s “misguided directives” promoting “broad use” of the drug, which he said “clearly lack scientific merit”.

The limited evidence around hydroxychloroquine so far has come in a steady stream of scientific studies, often as soon as they are posted online as “preprints” – ie before they have gone through the rigorous vetting process known as peer review. None of the studies that have been released meet the gold standard for demonstrating a drug’s effectiveness – a large-scale, double-blinded randomized controlled trial (RCT), though multiple trials of that kind are under way.

While the world awaits those results, here’s a guide to some of the studies released thus far: