Currently, the use of hydroxychloroquine for treating COVID-19 in the United States is not recommended by the Centers for Disease Control and Prevention (CDC) or the World Health Organization (WHO), as several studies have found it to be ineffective in treating COVID-19 and can have serious side effects.
Some early studies suggested that hydroxychloroquine could be an effective treatment for COVID-19, but subsequent larger and better-designed studies found no benefit or even harm from its use. Therefore, it is not considered an effective treatment for COVID-19 and is not recommended for use except in a clinical trial or as part of an emergency use authorization by the FDA for a specific patient.
It's worth noting that in the US, the FDA has revoked its Emergency Use Authorization for hydroxychloroquine for the treatment of COVID-19, citing potential risks and lack of efficacy.