Dr. Anthony Fauci, head of the US National Institute of Allergy and Infectious Diseases
Top disease researcher Dr. Anthony Fauci has told the US Senate that he would not be surprised if new coronavirus cases in the United States reach 100,000 per day.
He testified that the authorities are not in control of the outbreak and warned that not enough Americans are wearing masks or social distancing.
During Tuesday's hearing, Dr. Fauci said about half of all new cases come from four states: Florida, Arizona, Texas and California.
However, he warned: "We can't just focus on those areas that are having the surge. It puts the entire country at risk. We are now having 40-plus thousand new cases a day. I would not be surprised if we go up to a hundred thousand a day if this does not turn around, and so I am very concerned."
Earlier, the New York governor said nearly half of all Americans must self-quarantine if they visit the state.
On Tuesday, cases in the US rose by more than 40,000 in one day for the fourth time in the last five days.
The surge - which is occurring particularly strongly in southern and western states - has forced at least 16 states to pause or reverse their reopening plans.
For some, the new measures come over a month after they first began to reopen their economies.