An employee checks the production of chloroquine phosphate, resumed after a 15-year break, in a pharmaceutical company in Nantong city in east China's Jiangsu province Thursday, Feb. 27, 2020. Feature China | Barcroft Media | Getty Images

Hopes for a coronavirus treatment were boosted after President Donald Trump announced at a White House press briefing last week that two anti-malaria drugs were a "game-changer" that have shown "very, very encouraging results.'' But scientists and infectious disease experts say Trump's claims about the drugs — chloroquine and hydroxychloroquine — may be premature. While some small studies give doctors reason to hope, large clinical trials are needed to determine whether the drugs are truly effective in fighting COVID-19, they say. "We really need to continue to conduct research to find out what works," former Food and Drug Administration Commissioner Scott Gottlieb said Sunday on CBS' "Face the Nation." "Right now, there's no drug that looks like it's proven so overwhelming in early-stage clinical trials that we can say it's highly promising."

No proven therapies

None of the drugs being discussed has been put through rigorous clinical trials to fight CV-19, which has infected more than 487,000 people worldwide in less than three months.

Chloroquine has gained a lot of attention after a small study of 36 COVID-19 patients published March 17 in France found that most patients taking the drug cleared the coronavirus from their system a lot faster than the control group. Adding Azithromycin, commonly known as a Z-Pak, to the mix "was significantly more efficient for virus elimination," the researchers said. A small study in China also found that combining chloroquine with Azithromycin was "found to be more potent than chloroquine." Scientists point to Azithromycin as a possible treatment for CV-19 since it has been effective in fighting Ebola and Zika, two other deadly viruses. Though hopeful, the studies were too small to provide definitive conclusions. A 2005 National Institutes of Health study of chloroquine in SARS, which killed about 800 people across the world in 2003, was effective in preventing the spread of that coronavirus in primate cells.

Celebrity endorsement

The combined treatment even won a celebrity endorsement from "Lost" star Daniel Dae Kim, who said he has recovered from the disease. In a video he posted on Instagram, he said that although he wasn't a doctor, he credited hydroxychloroquine as the "secret weapon" in a cocktail of drugs prescribed by his doctor that helped him. All the hype has led to disastrous results for an Arizona man who took chloroquine phosphate, believing it would protect him from the coronavirus. His wife also took some and is in critical condition, according to NBC News. The toxic ingredient they consumed was not the medication form of chloroquine, used to treat malaria in humans. Instead, it was an ingredient listed on a parasite treatment for fish. The man's wife told NBC News she had watched televised briefings during which Trump talked about the potential benefits of chloroquine. There have also been reports of people stockpiling the drugs, which are needed to treat lupus and other diseases.

Clinical trials

To pass the FDA's muster, and win approval for widespread use, chloroquine and azithromycin will need to undergo rigorous clinical trials with thousands of participants — not a couple dozen, according to the agency's guidelines. "Many people in the world saw a small study that is helpful, but not even close to being conclusive," Isaac Bogoch, a University of Toronto infectious disease specialist, said in a phone interview with CNBC. Without a formal trial, it's difficult for doctors to tell whether the drug is actually working or whether a patient is improving from a strong placebo effect, said Eric Feigl-Ding, an epidemiologist and health economist at the Harvard T.H. Chan School of Public Health. "It's well known when you take a drug, you feel better psychology," he said.

Malaria treatment

Chloroquine is a decades-old drug that was approved by the FDA in 1949 to treat malaria. Its derivative, hydroxychloroquine, is often used by doctors to treat rheumatoid arthritis and lupus. Speaking at a White House press briefing last week, Trump said he felt "good" about the possibility of chloroquine and directed the Food and Drug Administration to investigate whether the drug can be used to treat the coronavirus. "It's shown very encouraging, very, very encouraging early results," Trump told reporters. "And we're going to be able to make that drug available almost immediately." He made similar comments at a briefing the next day, saying the administration is "accelerating the use of new drug treatments." On Saturday, he tweeted that he hopes FDA officials will put the medicine to use "immediately." tweet 1

'False hope'

Prominent U.S. health officials, including the National Institute of Allergy and Infectious Diseases director Dr. Anthony Fauci and FDA Commissioner Stephen Hahn, quickly played down Trump's claims. Hahn, also a physician said it was "important not to provide false hope," minutes after Trump said he felt good about the drug. Trump has "asked us to be aggressive" and "break through exciting, life-saving treatment, and we're doing that at the FDA," Hahn said. At a briefing Friday, Fauci said signs of the effectiveness of the drugs were "anecdotal" and said, "you really can't make a definitive statement."

'Optimistic'