Fauci warns US school reopening will be 'bridge too far' this year

America's top infectious diseases expert, Anthony Fauci, cautioned on Tuesday that it would be a "bridge too far" to think that treatment or vaccines would be ready in time to re-open schools and colleges in the Fall session this year, at a highly anticipated US Senate hearing on the domestic coronavirus outbreak.

"The idea of having treatments available or a vaccine to facilitate the reentry of students into the full term would be something that would be a bit of a bridge too far," Fauci said.

He explained that the drugs that have shown efficacy so far have been used on hospitalised patients and are not even close to being used as prophylaxis or treatment for students.

"Even at the top speed we're going, we don't see a vaccine, playing to the ability of individuals to get back to school this term," Fauci said, putting an official stamp on the medical questions surrounding the swirling debate over school reopening.

Fauci warned the Congress that reopening the economy too soon during the pandemic will result in "needless suffering and death."

He urged the states to "go by the guidelines", referring to the detailed rubric put out by the Centers for Disease Control and Prevention (CDC), but reportedly shelved by the White House.

Fauci, who is self-quarantining after a White House staffer tested positive for the virus, is one among four health experts testifying remotely to a Senate panel.

"At least eight candidate Covid-19 vaccines are in clinical development," Fauci said during his opening remarks. Fauci remained "cautiously optimistic" that at least one vaccine candidate will deliver an "efficacy signal".

Fauci is a crucial member of the White House coronavirus task force leading America's response to Covid-19, which has killed more than 80,000 people in the US.

America leads the world in coronavirus caseload. More than 1.3 million Americans have been sickened by the virus since the first reported case in January on the country's West Coast.