The nation’s top health officials warned on Tuesday the U.S. risks new outbreaks of coronavirus and possibly a broad resurgence if states and cities reopen too quickly. And they cautioned that neither a vaccine, nor surefire treatments would be available when schools are slated to reopen in the fall — a grim reminder that life would not soon return to normal even if Americans resume their routines.

Anthony S. Fauci, the nation’s top infectious-diseases expert, predicted Americans would experience “suffering and death that could be avoided,” as well as additional economic damage, if states ignore federal guidelines, including delaying reopening of most businesses until they see dramatic declines in cases. He also said the U.S. death toll from the coronavirus is probably higher than the 80,000 reported to date.

Fauci’s comments came during a contentious Senate hearing as lawmakers of both parties pressed him and other federal health officials on whether the country is ready to reopen. The panel’s chairman and all four witnesses appeared remotely because they all recently came into contact with people with confirmed infections — a testament to how the virus has transformed life even within the corridors of power.

Sen. Lamar Alexander (R-Tenn.), chairman of the Senate Health, Education, Labor and Pensions Committee, which held the hearing, is self-isolating at home after a staff member tested positive for the virus. Fauci; Stephen Hahn, head of the Food and Drug Administration; Robert Redfield, director of the Centers for Disease Control and Prevention; and Brett Giroir, an assistant secretary in the Department of Health and Human Services, all testified remotely after coming into contact with a White House aide who tested positive last week.

In his first congressional testimony since President Trump declared the coronavirus a national emergency on March 13, Fauci bluntly laid out the dangers of ignoring federal reopening guidelines.

“If some areas, cities, states or what-have-you, jump over those various checkpoints and prematurely open up without having the capability of being able to respond effectively and efficiently, my concern is that we will start to see little spikes that might turn into outbreaks,” said Fauci, director of the National Institutes of Allergy and Infectious Diseases. “I have been very clear in my message — to try, to the best extent possible, to go by the guidelines, which have been very well thought-out and very well-delineated.”

Giroir, who oversees the U.S. testing strategy, told senators the U.S. could be performing up to 50 million tests a month by September — but that would still amount to fewer than the 2 million to 3 million tests a day that experts have said is needed to ensure that people returning to work are infection-free.

The health officials also warned that a surge of cases in the fall could be especially challenging, when a coronavirus outbreak could coincide with flu season — in contrast to the president’s statements that the fall would not be worse. Redfield said the U.S. would need a five-to-10-fold increase in its capability to conduct contact tracing by the fall to identify all the known contacts of someone who tested positive for the virus in order to prevent an outbreak. He warned that individuals needed to remain vigilant in practicing social distancing measures for the next several months.

Fauci at one point contradicted statements made last week by Trump, when the president proclaimed the virus would disappear in coming months even without a vaccine.

“This is going to go away without a vaccine,” Trump said Friday, adding there could be “flare-ups,” including in the fall, but that covid-19 would go away regardless.

“That is just not going to happen,” Fauci said of the notion the virus would disappear on its own. “It’s a highly transmissible virus. It is likely there will be virus somewhere on this planet that will likely get back to us.”

The hearing often became combative, with Democrats criticizing Trump’s response to the pandemic and even Sen. Mitt Romney (R-Utah) scolding Giroir at one point for politicizing testing numbers. Romney said Giroir “celebrated” the fact that the U.S. is conducting more tests per capita than South Korea in a Rose Garden news conference on Monday, but ignored that South Korea had far greater testing capacity than the U.S. at the beginning of its outbreak and has only had 300 deaths.

“I find our testing record nothing to celebrate whatsoever,” Romney said.

Sen. Rand Paul (R-Ky.), who recovered after becoming infected with covid-19 earlier this year, questioned aspects of the scientific consensus during his questioning time, and in a combative exchange, told Fauci he was not the “end-all” for coronavirus decisions. Paul asserted that schools could reopen widely in the fall because the virus appears to be less dangerous in children.

“It’s not to say this isn’t deadly, but really, outside of New England, we’ve had a relatively benign course for this virus nationwide,” Paul said. “And I think the one-size-fits-all, that we’re going to have a national strategy and nobody is going to go to school, is kind of ridiculous. We really ought to be doing it school district by school district, and the power needs to be dispersed because people make wrong predictions.”

After asking to respond, Fauci told Paul, “I’ve never made myself out to be the end-all.” He warned that while the numbers indicate the pathogen is less dangerous to children than adults and the elderly, “we don’t know everything about this virus.” He noted a spate of new cases of coronavirus-infected children presenting with a “very strange inflammatory syndrome.”

“I am very careful and hopefully humble in knowing that I don’t know everything about this disease, and that’s why I’m very reserved in making broad predictions,” Fauci said.

In response to repeated questions about when better therapeutics and a vaccine would be available, Fauci dismissed the notion they might be in use by the time schools reopen in the fall.

“The idea of having treatments available or a vaccine to facilitate reentry of students into fall term would be something that would be a bit of a bridge too far,” he said. “The drug that has shown some degree of efficacy was modest and in hospitalized patients” only, he added, referring to remdesivir, the Gilead antiviral drug that has shown to reduce recovery time for people with covid-19. But Fauci said that remdesivir alone was not sufficient as a therapeutic.

Asked by Sen. Elizabeth Warren (D-Mass.) whether the virus is contained in the U.S., Fauci chose his words carefully. “I think we are going in the right direction,” he said. “But the right direction does not mean we have by any means total control of this outbreak.”

Find live updates about Fauci’s testimony below.