The rush to find a treatment for the novel coronavirus continues to intensify as the number of diagnosed cases around the world grows significantly.
Globally, there are at least 278,000 diagnosed cases with more than 11,000 virus-related deaths, according to Johns Hopkins University. The increase in COVID-19 numbers is upping the pressure on world leaders and scientists to deliver.
The nation's top infectious disease doctor, Anthony Fauci, however, cautioned that there isn't enough evidence to support claims it will work to help patients with COVID-19.
Still, FDA Commissioner Stephen Hahn said "the president has directed us to take a closer look at, as to whether an expanded-use approach to that could be done to actually see if it benefits patients [with coronavirus]."
Chloroquine and a nearly identical drug called hydroxychloroquine both have mild side effects. They would be taken by people who are already sick, but could also potentially be taken by people who are healthy to help prevent infection.
While chloroquine is definitely being looked at as an option to combat the virus, it's not the only one. Scientists and medical professionals are looking at several options for coronavirus treatments.
Separately, scientists are also working on a vaccine, which would be given to people who are healthy to protect them from getting sick if they are exposed to the virus. But experts say a vaccine is one to two years away.
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Here is a breakdown of some of the experimental drugs being evaluated for COVID-19. Please note these are treatments for people who are already sick, not vaccines. Some of these are already being tested in clinical trials. Some may also be available through "compassionate use," which is an emergency program so that very sick patients can try an unproven therapy.
Even if successful, these treatments would not necessarily be "cures" for COVID-19, but rather an extra tool doctors can use to help people who become extremely sick.
This is an experimental therapy not currently approved to treat any disease. It was studied for Ebola but didn’t work as well as other drugs, so it didn't move forward. Today it’s seen by U.S. medical experts (including Fauci, who is the director of the National Institute of Allergy and Infectious Diseases) as one of the best hopes for COVID-19.
It also showed promise for SARS in laboratory experiments.
Data on this drug could come in as early as next month. There are three major trials ongoing with study sites in the U.S. Two are sponsored by Gilead Sciences, the company behind the drug, and one is sponsored by the NIAID.
Chloroquine is an approved malaria drug in many countries, but it's not currently approved to treat COVID-19 in the U.S.
Researchers in China studied it in COVID-19 patients with pneumonia and found they had shorter hospital stays. On Thursday, Hahn said the agency would start clinical trials of a nearly identical drug, hydroxychloroquine, for patients with COVID-19 infection.
Fauci warned about the lack of scientific proof, however, and said that any signs of success were "anecdotal."
"The information that you’re referring to specifically is anecdotal. It was not done in a controlled clinical trial," Fauci said at the coronavirus task force news conference. “So you really can’t make any definitive statement about it,” he said at a press conference.
Experts say it could also be used to prevent infection, though this will also have to be studied.
There are clinical trials ongoing in China and more scheduled to start in England, Thailand, South Korea and the United States.
Bayer is among several drug companies that make chloroquine and it said this week it's donating 3 million tablets of the drug Resochin (chloroquine phosphate) to the U.S. government.
Kaletra has been approved to treat HIV, but not approved to treat COVID-19.
It’s an antiviral drug, so some believe it may be effective for COVID-19, a disease caused by a virus. However, early results are not promising.
It didn’t make much of a difference, according to results published this week of a clinical trial in COVID-19 patients.
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This drug is approved in Japan to treat the flu but is not approved to treat novel coronavirus.
Zhang Xinmin, an official at China’s science and technology ministry, said favipiravir produced encouraging outcomes in clinical trials in Wuhan and Shenzhen involving 340 patients. However, the results haven't been peer-reviewed and Fujifilm, the company that makes the drug, declined to comment on the study results.
Human trials are ongoing in China and possibly Thailand.
Nafamostat is a blood clot medicine approved in Japan but it's not approved for COVID-19.
In 2016, scientists identified the potential for nafamostatr, made by Nichi-iko Pharmaceutical Co, to inhibit the virus that caused MERS.
Clinical trials are expected to begin within in a month in Japan and results won't be available for some time.
Monoclonal antibodies are a type of medicine made up of proteins. Many companies are attempting to make this type of medicine for COVID-19.
These antibodies are proteins produced by the immune system that can neutralize pathogens. This approach has worked before for other infectious diseases.
Regeneron, one of several companies working with monoclonal antibodies, says its clinical trials could start in the early summer. Results will not be available for some time.
This is a treatment, not a drug. Commissioner Han spoke about this approach on Thursday.
Treatment using convalescent plasma is done by taking the blood of someone who is already infected and recovered from the coronavirus and then infuse the infection-fighting antibodies into someone who is newly infected, or someone who is likely to be infected. This would be both a treatment and a quasi-vaccine (protective). But the underlying idea is that it will help the immune system fight off the infection.
Johns Hopkins hopes to start testing it on people soon.
ABC News' William Mansell contributed to this report.