US President Donald Trump has been given a dose of an experimental antibody drug manufactured by giant biopharma firm Regeneron, which has a major plant at Limerick, where it employs over 1,000 people.

The White House announced last night that President Trump had been given a single 8g dose of Regeneron's antibody cocktail REGN-COV2, before he was moved to the Walter Reed National Military Medical Centre in Maryland.

The antibody is being manufactured at its New York facility, but the company announced last month that it was creating an additional 400 jobs at its Limerick campus to allow the company to maximise its capacity at its NY plant, and change how some of its operations work in light of the Covid pandemic.

Regeneron said it had agreed to supply a single dose, administered intravenously, for President Trump at the request of his physician under "compassionate use" provisions.

The antibody treatment is still undergoing clinical trials among 275 patients who have Covid-19 and are being treated in non-hospital settings.

But the trials are showing very promising results. Just this week, Regeneron posted that the antibody medication has reduced viral levels and improved symptoms in non-hospitalised Covid-19 patients.

It also showed positive trends in reducing medical visits.

The trial is part of a much larger programme, which also includes studies of the treatment of patients in hospital, and studies on the prevention of infection of people who have been exposed to Covid-19 patients.

Regeneron's President and Chief Scientific Officer, George D Yancopoulos, said after months of very hard work they were extremely grateful to see that Regeneron's antibody cocktail REGN-COV2 rapidly reduced viral load and associated symptoms in infected Covid-19 patients.

He said they were highly encouraged by the robust and consistent nature of this initial data, as well as the encouraging well-tolerated safety profile, and have begun discussing their findings with the regulatory authorities while continuing their trials.

"We all know that for President Trump, and anyone infected by the virus, it is a battle between the virus and your immune system, which makes antibodies that will bind and kill the virus. For most people, they make good antibodies, and a lot of them, fast enough to kill it before the virus takes over and has devastating consequences," he said.

However, Mr Yancopoulos said that sometimes people do not make enough fast enough, and the virus can win.

"This cocktail specific for Covid-19 supplements, replaces or substitutes for someone's immune system," he said.

The drug is similar to an antibody cocktail to treat Ebola, which will be manufactured at Regneron's plant in Limerick once it receives formal FDA approval.