Unless Americans wear masks and recommit to social distancing, the daily increase in new cases nationwide, now around 40,000, could reach 100,000, Dr. Anthony Fauci, the head of the National Institute of Allergy and Infectious Diseases, told a U.S. Senate committee. "I would not be surprised if we go up to 100,000 a day if this does not turn around, and so I am very concerned".
"I think it is important to tell and you the American public that I'm very concerned because it could get very bad", Fauci said.
Fauci said G4 is still in the examination stage - "It's not so-called, an immediate threat". "We're in the middle of catastrophic outbreak, and we really do need to be guided by scientific principles".
The G4 virus, which is genetically descended from the H1N1 swine flu that caused the 2009 pandemic, was described in a study published in the Proceedings of the National Academy of Sciences on Monday.
He added: "We are now having 40-plus thousand new cases a day".
"What we've seen in several states is several iterations of that".
Sen. Lamar Alexander, R-Tenn., the chairman of the committee, said at the hearing that he personally urged President Donald Trump to wear a mask.
Sen. Bernie Sanders, I-Vt., asked the panelists whether they would support an effort to increase the production of masks in this country and distribute them free of charge.
"There are some states in which the leadership and the decision [to open up] was a little too precipitous", he said.
But when asked by CNN senior medical correspondent Elizabeth Cohen whether the USA can get to herd immunity if 25% of the population refuses to get a coronavirus vaccine with that rate of effectiveness, Fauci said, "No, unlikely". "They would follow his lead".
Fauci, a member of the White House coronavirus task force, said the federal government has "a lot of work to do" in encouraging Americans to get inoculated once there is a coronavirus vaccine available to the public.
Anthony Fauci, the head of the National Institute of Allergy and Infectious Diseases, also cautioned against pinning hopes on a vaccine. Florida's Miami-Dade County reported its highest numbers of hospitalizations, intensive-care patients and ventilator use in at least two months. As for a vaccine, Fauci says that a safe and effective vaccine is not guaranteed, but experts are hopeful that doses will be available to the public by next year.
New Zealand declared the country infection-free on 8 June, and since then has had to contain several cases that came from worldwide travellers.
So far, more than 125,000 people in the United States have died from coronavirus infections, according to the Centers for Disease Control and Prevention.
The president himself has bucked conventional wisdom on slowing the spread of COVID-19, holding large in-person events as part of his reelection campaign.