"I can't make an accurate prediction, but it is going to be very disturbing", he said.
"I mean, for the Fourth of July, we could all show our patriotism with a red, white and blue mask, going out there and showing some strength", he said in an appearance on "Fox & Friends".
Infections are rising rapidly mostly in parts of the West and South, and Fauci and other public health experts said Americans everywhere will have to start following key recommendations if they want to get back to more normal activities like going to school.
But the chairman of the panel, Republican Senator Lamar Alexander, also pointed the finger at Mr Trump, and said the president had the power to end politicisation of mask-wearing that suggests "if you're for Trump, you don't wear a mask. If you're against Trump, you do", said the chaiman, Sen.
Redfield singled out younger Americans in particular to deliver a message that they are not exempt from the necessity of wearing a mask. The president has plenty of admires. "They would follow his lead".
The big picture: More than 50% of the new infections in the US are from states like Florida, Texas, California and Arizona that have hot spots. The U.S. has recorded more than 2.6 million Covid-19 cases in total, with more than 126,000 deaths from the virus, according to data compiled by Johns Hopkins University. That is 30 percent higher than the peak of 34,203 on April 25, the peak day in the original surge of covid cases this spring.
The nation's top infectious-disease expert gave the warning in response to questioning from Sen. "I will guarantee you that, because when you have an outbreak in one part of the country, even though in other parts of the country they're doing well, they are vulnerable". It puts the entire country at risk.
Speaking with CNN over the weekend, Dr. Fauci-director of the National Institute of Allergy and Infectious Diseases-first spoke on the current problem with bafflingly bold community spread.
But when asked by CNN senior medical correspondent Elizabeth Cohen whether the US 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".
"We have an obligation to use all of our scientific knowledge, regulatory framework to ensure that any vaccine that comes before us, whether for authorization or approval, meets our stringent standards for safety and effectiveness", he told lawmakers.
Trump spent crucial weeks early on downplaying the threat posed by the virus in an effort to boost the stock market.