A logo sits on display on a building at the Novartis AG campus in Basel, Switzerland, on Wednesday, Jan. 16, 2019.

Novartis will donate enough doses of malaria drug hydroxychloroquine to treat several million patients in the fight against the coronavirus, if it wins approval, the Swiss company said on Friday.

There are no vaccines or treatments approved for the disease, but there is currently a 1,500-person trial, led by the University of Minnesota, to see whether hydroxychloroquine can prevent or reduce the severity of COVID-19. Two other trials are studying blood pressure drug losartan as a possible treatment.

Novartis makes the malaria drug, which is also used to treat lupus and rheumatoid arthritis, at its Sandoz unit in the United States. It plans to donate 130 million doses of the drug and is in talks with U.S. Food and Drug Administration regulators over expanding its use for coronavirus.

"Novartis is supporting ongoing clinical trial efforts, and will evaluate needs for additional clinical trials," it said in a statement.

In Washington, U.S. President Donald Trump said during a news conference on Friday he is optimistic about the malaria treatment's use against COVID-19.

Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases, did not take issue with Trump's optimism, but said the drug's promise is based so far on anecdotal evidence in France and that more data is needed.

"What I'm saying is that it might - it might - be effective. I'm not saying that it isn't," Fauci said.

Fauci also said that while toxic reactions to the drugs are rare based on decades of patient use and can be reversible in many cases, that is not known for COVID-19.

"What we don't know is when you put it in the context of another disease whether it's safe. Fundamentally, I think it probably is going to be safe, but I like to prove things first," Fauci said.

Novartis has 50 million doses in stock, and hopes to produce another 80 million by the end of May for donation. The donations may be sufficient to treat several million patients, depending on the dosing regimen, Novartis said.

The American Society of Health-System Pharmacists (ASHP), added hydroxychloroquine to its list of drugs in short supply this week. Four out of eight manufacturers of the drug are in short supply, it said.

Bayer AG has donated three million tablets of the malaria drug Resochin, which is similar to hydroxychloroquine, to the U.S. government for potential use against coronavirus.

Mylan NV is ramping up production and expects to begin supplying it more broadly in mid-April. It said with the raw materials on hand it can make 50 million tablets to potentially treat more than 1.5 million patients.

Teva Pharmaceuticals Industries Ltd said it would donate more than six million doses of hydroxychloroquine sulfate tablets.