An international poll of more than 6,000 doctors finds that the antimalarial drug hydroxychloroquine has been deemed the most highly rated treatment for the novel coronavirus.

The survey, conducted by Sermo, a global health care polling company, asked 6,227 physicians in 30 countries to find out what is the most effective against SARS-CoV-2. The poll finds that 37% of those treating patients suffering from the coronavirus that causes COVID-19 rated hydroxychloroquine as the “most effective therapy” out of a list of 15 choices.

On Monday, the U.S. Food and Drug Administration gave chloroquine and its derivative, hydroxychloroquine, emergency-use authorization, although many physicians were already using the drug.

Azithromycin, known by the brand name Zithromax or Z-Pak, came in as the second-most effective therapy at 32%, followed by “nothing.”

Hydroxychloroquine, which is sold under the brand name Plaquenil, was prescribed mainly in the United States for the most severe cases. “Outside the U.S., hydroxychloroquine was equally used for diagnosed patients with mild to severe symptoms whereas in the U.S. it was most commonly used for high risk diagnosed patients,” the survey found.

Sermo released a statement on the poll with other findings, including:

The three most commonly prescribed treatments amongst COVID-19 treaters are 56% analgesics, 41% Azithromycin, and 33% Hydroxychloroquine

Hydroxychloroquine usage amongst COVID-19 treaters is 72% in Spain, 49% in Italy, 41% in Brazil, 39% in Mexico, 28% in France, 23% in the U.S., 17% in Germany, 16% in Canada, 13% in the UK and 7% in Japan

Hydroxychloroquine was overall chosen as the most effective therapy amongst COVID-19 treaters from a list of 15 options (37% of COVID-19 treaters)

75% in Spain, 53% Italy, 44% in China, 43% in Brazil, 29% in France, 23% in the U.S. and 13% in the U.K.

The two most common treatment regimens for Hydroxychloroquine were:

(38%) 400mg twice daily on day one; 400 mg daily for five days

(26%) 400mg twice daily on day one; 200mg twice daily for four days

Globally, 19% of physicians prescribed or have seen Hydroxychloroquine prophylactically used for high risk patients, and 8% for low risk patients, Sermo said.

President Donald Trump has been a big booster of the anti-malarial drugs, expressing optimism about the drugs that he said could be “one of the biggest game changers” in medicine.

“HYDROXYCHLOROQUINE & AZITHROMYCIN, taken together, have a real chance to be one of the biggest game changers in the history of medicine,” Trump wrote on Twitter. “The FDA has moved mountains – Thank You!”

In his tweet, Trump was referring to a French study that the drug combo can be effective in counteracting the coronavirus COVID-19, which has spread across the world after emerging in China.

“Despite its small sample size, our survey shows that hydroxychloroquine treatment is significantly associated with viral load reduction/disappearance in COVID-19 patients and its effect is reinforced by azithromycin,” the study found.

“French confirmed COVID-19 patients were included in a single arm protocol from early March to March 16th, to receive 600mg of hydroxychloroquine daily and their viral load in nasopharyngeal swabs was tested daily in a hospital setting,” the researchers wrote in an abstract, Fox News reported. “Depending on their clinical presentation, azithromycin was added to the treatment.”