With no known drug therapies or vaccines available for the highly contagious new coronavirus, the US Food and Drug Administration (FDA) is looking to a treatment that has worked during previous outbreaks: transfusion of plasma from recovered patients to the severely ill.

Those who have recovered from the coronavirus have developed antibodies in their blood that fight infections, known as "convalescent plasma", which may help boost the immunity of patients battling the COVID-19 disease.

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The FDA on Friday announced a programme with "expanded access" which will provide convalescent plasma to patients nationwide, collected and distributed by the American Red Cross.

One donation can generate nearly four units of plasma and could possibly help up to four people; however, it is not yet known to be a safe and effective treatment for COVID-19.

The clinical trials are led by the Minnesota-based Mayo Clinic, who will examine whether antibody therapy may shorten the duration of illness, the severity of the disease, or prevent people from dying.

The therapy may prove to be a useful method in boosting the immune system of front-line health workers.

Thousands of units of plasma are to be distributed to patients in need in the coming weeks, according to the FDA.

'Hopefully, he can be saved'

Francis Suarez, the mayor of Miami, become on Friday the first person in the state of Florida to participate in this experimental treatment following his recovery from the coronavirus and having been symptom-free for at least two weeks.

Researchers hope his plasma can help a critically ill coronavirus patient in the area.

"I got three or four Instagram messages asking if I'd be willing to donate blood or plasma," Suarez said.

"I called back the patient's family right away. They were very emotional, very grateful, and are very hopeful that with this donation, hopefully, he can be saved."

When donating, the blood of recovered patients is drawn and piped through a special machine to extract the yellow-coloured serum.

Donors then get their red cells and platelets back, in a process that takes a little longer than donating blood.

Recipients will then, in theory, be able to share the donor's immunity.

The treatment predates vaccines, and was used to fight the 1918 flu pandemic, as well as more recent outbreaks of the coronavirus family such as SARS and MERS.

The FDA gave New York State's Department of Health permission to conduct the experimental procedure last month, but it has only been used on a handful of patients so far.

The testing comes as the US braces for a "peak death week" according to an official as hospitals struggle to maintain capacity for infected patients.

On Monday, the US death toll from the coronavirus surpassed the 10,000 mark according to a tally from Johns Hopkins University, with more than 347,000 confirmed infections.

Can it work?

Steven Spitalnik, a transfusion medicine doctor at Columbia University, said there is still a lot about the immune response to coronavirus that is not yet understood.

"We're assuming it's similar to other viruses and there are good reasons to think that. We think that within seven to 14 days after the onset of an infection, that people will develop an immune response and eventually make high amounts of antibodies.

"Although exactly when the peak of antibody production will be, we don't know. And how long it will stay permanent, we also don't know that either."

Institutions in 20 US states are coordinating their research through a national COVID-19 programme to answer such questions.

They hope to discover therapeutic treatments that will help reduce the number of infections, and ease pressure on hospitals and healthcare workers.

"It's a 100-year-old proven therapy," Muhammad Munir, a virologist at UK's Lancaster University, told Al Jazeera. "Certainly, this has an advantage especially for front-line workers, doctors and nurses who are highly exposed to the virus."

However, he added there are a series of factors that need to be taken into consideration.

"If you use the plasma in the later stages of the infection, the chances for the survival would be relatively less. You have to apply the plasma in the earliest stages of infection, when the proportion of the virus is relatively less, and equate with the level of antibodies in the plasma," Munir said.

He added that acquiring enough plasma to meet the demand of people is a major challenge, too. It requires having enough diagnostic capabilities to screen people who are infected and have enough antibodies in their blood that can be used as treatment.

Meanwhile, donors and patients have to be matched by blood type, as with regular, blood donation.

According to Munir, strong leadership is needed to encourage people to donate in order to scale up at the required quantity.