WASHINGTON (NYTIMES) - Dr Anthony Fauci, the United States's top infectious disease expert, told members of Congress on Tuesday (June 23) that the nation does not yet have the coronavirus under control and is seeing a "disturbing surge" of infections in some parts of the country, as Americans ignore social distancing guidelines and states reopen without adequate plans for testing and tracing the contacts of those who get sick.

Fauci's assessment, delivered during a lengthy hearing before the House Energy and Commerce Committee, painted a much grimmer picture of the coronavirus threat than the one given by President Donald Trump, who said last week that the virus that had infected more than 2 million Americans and killed more than 120,000 would just "fade away".

"The virus is not going to disappear," Fauci said.

To the contrary, he said the next two weeks would be critical to controlling the spread of the virus, and he warned of a dangerous situation looming this winter, when the regular flu season will intersect with the coronavirus, producing "two respiratory-borne infections simultaneously confounding each other".

Fauci also delivered a stern message to young people, saying they could endanger others by ignoring the coronavirus threat. And after mass protests for racial justice that have drawn huge crowds and a campaign rally that Trump held in Tulsa, Oklahoma, despite public health warnings, he gently suggested that Americans needed to do a better job of taking precautions to reduce the virus' spread.

"Plan A: Don't go in a crowd," he said. "Plan B: If you do, make sure you wear a mask."

Fauci's testimony, and the testimonies of three other doctors who have helped lead the government's coronavirus response, cast a dark cloud over the sunny accounts offered by the president as he has portrayed the United States as a nation bouncing back from the brink.

Shortly before the hearing began, Trump used Twitter to complain that he was not getting credit for his response to the virus, noting that Fauci, "who is with us in all ways", has "a very high 72% Approval rating" - much higher than the president's, which stands around 41 per cent.

Fauci, who has run the National Institute of Allergy and Infectious Diseases since 1984, was the only witness who is not a political appointee of the president's. But the others - Admiral Brett Giroir, the assistant secretary for public health; Dr Stephen Hahn, the commissioner of food and drugs; and Dr Robert Redfield, the director of the Centers for Disease Control and Prevention - struck a similarly somber tone.

Redfield called the pandemic "the greatest public health crisis our nation and our world have confronted in more than a century", and one that had "brought this nation to its knees," cautioning that when it coincides with flu season this year, hospitals and health workers would face a tremendous strain. Getting a flu shot, he said, would be even more important this year.

"This single act will save lives," Redfield said.

And all four doctors contradicted the president's assertions about testing, saying that despite Trump's claim at the rally in Tulsa that he had asked "my people" to "slow the testing down" because increased screening was revealing more infections, making the country look bad, they knew of no such request.

"We are proceeding in just the opposite - we want to do more testing and of higher quality," said Giroir, who has been designated the "testing czar" by the president. "The only way that we will be able to understand who has the disease, who is infected, and can pass it, and to do appropriate contact tracing is to test appropriately, smartly - and as many people as we can."

And both Fauci and Redfield expressed concern about Trump's decision late last month to withdraw from the World Health Organization, saying that they had maintained long-standing relationships with the WHO even as the White House moved to punish it over its relationship with China.

Fauci himself brought two masks to the hearing, a black one that he wore for the first few hours and a red one emblazoned with logos of the Washington Nationals baseball team, of which he told the panel he was "an avid fan".

Questioned about Trump's refusal to wear a mask, Fauci did not directly criticise the president, but he told lawmakers that it was important for public officials like him to wear face masks, "not only because I want to protect others and to protect myself, but also to set an example".