WASHINGTON, Aug. 23 (AFP) - American authorities announced on Sunday (Aug 23) an emergency authorisation for doctors to use blood plasma from recovered COVID-19 patients as a treatment against the disease that has killed more than 176,000 in the US.

The move by the Food and Drug Administration comes as President Donald Trump faces intense pressure to curb the contagion that has hobbled the world's largest economy and clouded his once-promising prospects for re-election in November.

The plasma is believed to contain powerful antibodies that can help fight off the disease faster and help protect people from being seriously hurt by it.

"This product may be effective in treating COVID-19 and ... the known and potential benefits of the product outweigh the known and potential risks of the product," FDA said in a statement.

While the treatment has already been used on patients in the United States and other nations, the extent of its effectiveness is still debated by experts and some have warned that it could carry side effects.

"Convalescent plasma probably works - though it still needs to be proven in clinical trials - but not as a rescue treatment for people who are already severely ill," said Len Horovitz, a pulmonary specialist at Lenox Hill Hospital in New York City.