Shafaq News/  The United States' top infectious disease scientist on Monday hailed early results from Moderna's Covid-19 vaccine trial as "stunningly impressive," calling the findings an emphatic validation of experimental mRNA technology that some had doubted.

"I must admit that I would have been satisfied with 70 or at the most 75 percent efficacy،" he told AFP.

"The idea that we have a 94.5 percent effective vaccine is stunningly impressive. It is really a spectacular result that I don't think anybody had anticipated would be this good."

Fauci leads the National Institutes of Allergies and Infectious Diseases (NIAID), which began co-developing the vaccine with the US biotech company in January, shortly after China shared the genetic sequence of the new coronavirus.

The vaccine is based on a relatively new technology that uses a synthetic version of a molecule called "messenger RNA" to hack into human cells, and effectively turn them into vaccine-making factories.

No vaccine based on this platform has ever been approved.

"There were many people who had reservations about using something that had not been tried and true over the years; in fact, some people even criticized us for that," said Fauci.

On Monday, Moderna and NIAID announced their preliminary results based on 95 of the 30,000 volunteers they had recruited who fell ill with Covid-19.

Of the 95, 90 had been in the trial's placebo group, and five in the group that received the drug, called mRNA-1273, translating to an efficacy rate of 94.5 percent.

Fauci recalled that some had questioned whether the vaccine would prevent severe forms of Covid-19, not just mild or moderate cases -- and this too had been resoundingly answered.

"There were 11 severe events, none in the vaccine group -- 11 in the placebo group, so that settles the question of whether it prevents severe disease, which it definitely does."

It follows a similarly impressive result from American pharmaceutical firm Pfizer and its German partner BioNTech last week, which reported an efficacy of 90 percent for their vaccine.

Asked whether it was too early to say if mRNA technology had now been proven, Fauci -- who is usually known for his cautious statements -- said the jury was definitely in.