Convalescent plasma is front and center in talks among medical experts following the U.S. Food and Drug Administration's emergency-use authorization for blood plasma.

Experts Question FDA's Move

Late Sunday the U.S. Food and Drug Administration issued an emergency-use authorization for convalescent plasma - a potential but as yet unproven treatment for COVID-19.

Medical experts have questioned the FDA's decision and suggested it may have been pressured by the White House. FDA commissioner Dr. Stephen Hahn has denied the allegations.

U.S. President Donald Trump called the emergency-use authorization "historic."

Hahn, however, said the decision was made on medical reasons alone. "I've never been asked to make any decision at the FDA based on politics," he said.

Trump Hails Convalescent Plasma as 'Powerful Therapy'

At a news conference Sunday, Trump referred to the potential treatment as a "powerful therapy." He said convalescent plasma could "save countless lives."

However, health experts said there was little evidence to date pointing to convalescent plasma as a sure treatment against viruses.

There is some evidence convalescent plasma helps in other infections such as severe acute respiratory syndrome but no evidence of it being effective against COVID-19 has been published.

Inside the Clinical Trials for Convalescent Plasma

While hopes are high for convalescent plasma as an effective treatment there have been stumbling blocks.

Clinical trials into the use of convalescent plasma for COVID-19 have been delayed because many researchers have focused on studying other therapies - such as hydroxychloroquine.

Scientists working on blood plasma studies have struggled to find volunteers. Trials started this month only - following the failure of sure results from hydroxychloroquine and other therapies.

One trial has signed up 100 participants only out of 1,000 expected to take part. It remains to be seen if more volunteers will take part following the FDA's emergency-use authorization.

Trump Accuses FDA of Delaying Vaccine

Trump continues to put pressure on vaccine trials. This past weekend Trump accused the FDA of "making it very difficult" for pharmaceutical companies to gather volunteers for human trials.

The trade group Biotechnology Innovation Organization said while the pharmaceutical industry would like to deliver a COVID-19 vaccine as soon as possible it could only "move as fast as the science allows us."

The FDA hasn't commented on Trump's accusations.

As of Sunday the U.S. was the world's worst-affected country with at least 5,874,146 confirmed coronavirus cases and around 180,604 deaths.