Anti-malarial treatment hailed by Trump has no benefit for coronavirus patients, French researchers find - Study is the most comprehensive done on hydroxychloroquine treatment for Covid-19 patients

It's a fair warning, but it's more important to be cautious when the preliminary results are positive.

In this case, it suggests people shouldn't use that treatment. Given that it strengthens the case for caution, it's not as damaging as if it strengthened the case of using the drug.

Basically, what doctors should've been doing up to now is avoid prescribing that medicine for COVID-19 patients until there was more information on it. This basically confirms that they were right to wait.