The malaria drug hydroxychloroquine might not be effective in treating patients with Covid-19, a new study finds.

The report published by the Journal of Zhejiang University in China tested if coronavirus patients who received the medication were more likely to recover than those who didn’t, and it found that was not the case.

This limited study only looked at 30 patients and contrasted the study from France, which looked at 40 patients. In France, its study found the virus decreased in patients when used with the combination of an antibiotic.

France’s study encouraged President Donald Trump to advertise the potential benefits with the US to help treat the novel virus. Last week, he called the drug combination a “game-changer” even though the Food and Drug Administration (FDA) warned it might not work and has yet to approve it for Covid-19.

But the FDA approved drug trials in New York state with more severe Covid-19 patients to see if the combination of hydroxychloroquine and an antibiotic would help. These trials started on Tuesday, and Governor Andrew Cuomo said he was “optimistic” about the results.

Nevada‘s governor, Steve Sisolak, banned the use of hydroxchloroquine and chloroquine to treat coronavirus patients after the contradictory reports on if the drugs actually worked against the virus.

Mr Sisolak said there was no consensus among experts or Nevada doctors that the drug combination would be beneficial to patients.

His executive order also limited prescription orders to only allow a 30-day supply. This limitation was to ensure the drug was used for “legitimate medical purposes”, such as lupus patients or people with malaria.

An interest in the drug has caused problems across the US, including people wrongly using the medication to treat Covid-19 symptoms.

An Arizona man died after he self-medicated with an additive used to clean fish tanks, which included chloroquine phosphate. His wife also took the mixture and is now in the ICU battling the drug effects of the solution.

When speaking to NBC News, the woman said the couple decided to try to mixture after hearing about the drug’s potential benefits during the president’s press conferences. They were “afraid of getting sick” from the virus.

Drug shortages for chloroquine and hydroxchloroquine have also escalated across the country, with pharmacists reporting that doctors are misusing their positions by prescribing the drugs for themselves and family members.

States including Nevada, Illinois, Ohio, North Carolina, and Texas have noticed doctors hoarding the prescriptions and released recommendations to deter any abuse by prescribers.