The US set another record for new coronavirus cases just days before the July Fourth weekend -- with at least 23 states pausing reopening plans to combat mounting infections.
There were 50,203 new coronavirus cases reported nationwide Wednesday, a single-day record. It took a little over two months to record numbers close to that nationwide when the pandemic started. Last week, new cases had also soared to a record high.
At least five states -- Arizona, California, North Carolina, Tennessee and Texas -- reported a record number of new cases Wednesday. And health officials are urging Americans to limit their holiday weekend festivities to avoid clusters of outbreaks.
"We know people are tired of being cooped up at home ... but cases surged after Memorial Day," said Dean Sidelinger, the Oregon state health officer. "We don't want the same thing to happen over the Independence Day holiday."
In Nebraska, officials warned residents to maintain a contact list for future tracing if they have to invite guests over for the holiday. They urged people to hold such events outdoors if possible, avoid sharing items such as sun screen and maintain social distancing.
The Fourth of July weekend could be the "perfect storm" for a spike in coronavirus cases, said Dr. Joshua Barocas, an infectious disease physician at Boston Medical Center.
"The combination of travel, the combination of reopening -- perhaps in some cases, too early -- and the combination of people not necessarily following some of these preventive guidelines," he said.
FDA commissioner 'cautiously optimistic' on vaccine
One thing that could slow the march of the coronavirus is the development of a vaccine. US Food and Drug Administration Commissioner Dr. Stephen Hahn said Thursday that the US remains on target to have a vaccine available by the end of December or early next year.
"FDA has given authorization to proceed with clinical trials for four separate vaccines and we've seen a number of vaccine developers come forward -- double digit numbers -- so we have a lot of different, if you will, shots on goal with respect to vaccines. That's good news," Hahn told ABC's Whit Johnson during an appearance on "Good Morning America."
"We expect two of these vaccines to go in the late stage of clinical trials, which are large clinical trials, in this month," Hahn said. "We are on target to reach a vaccine by year's end or early next year, so I'm cautiously optimistic. Of course it depends upon the data that are generated from the trial."
Keep bars closed for schools to reopen in the fall
The virus has killed about 128,000 people and infected more than 2.6 million nationwide, according to Johns Hopkins University.
With the surging number of new cases, quick actions now will determine what happens in the next few months, experts said. If governors want schools to reopen in the fall, they have to contain the amount of coronavirus in their communities now, Dr. Ashish Jha told CNN's Jake Tapper.
"When they understand the choices in stark terms -- schools this fall or bars now -- those are your choices ... I think more and more governors, even in places that aren't having large outbreaks, are realizing that maybe we can avoid bars in the summer and fall, if that gives us a better shot at getting schools open this fall," said Jha, the director of the Harvard Global Health Institute.
"The single biggest determinant of whether we're going to be able to open schools and keep schools open is how much virus there is in the community," Jha added. "So when I look at large parts of the country right now, and think if that's the level of virus we have going into September, we're not going be able to keep schools open."
To do that, officials have to go beyond keeping some public sites closed.
"You can't have bars and gyms open. I'm not sure you have restaurants open. You've got to have mandatory mask-wearing and you've got to push on surveillance, testing, tracing -- all the stuff we've been talking about," Jha said.
The virus shows signs of resurgence
As new cases rise and states rethink reopenings, some areas that had made progress against the virus are showing signs of resurgence.
California was one of the first states to shut down with some of the most stringent measures. On Wednesday, it reported 9,740 new cases -- a number that included over 3,800 previously unreported cases from a five-day period, officials said.
More than 28 million Californians live in counties where restaurant dining rooms, bars and other indoor facilities have been ordered to stay shut as Covid-19 cases increase. The closures affect 72% of the state's population, and include restaurants, breweries, museums, zoos and movie theaters for at least three weeks, Gov. Gavin Newsom said.
"Bottom line is, the spread of this virus continues at a rate that is particularly concerning," Newsom said.
Michigan is closing indoor service at bars throughout most of the lower part of the state.
Other states including Florida, Georgia, Idaho, Louisiana, Maine and Nevada -- which have all seen more than a 50% increase in cases -- have paused or rolled back their reopening plans.
"If you have bars, you have music. If you have music, you want to socialize. And you want to speak louder than usual so you can overcome the background noise," said Dr. Ricardo Franco, assistant professor of medicine at the University of Alabama at Birmingham.
All those factors can increase the spread, Franco added.
There's still a chance to turn things around
While predictions are dire, the US can turn the resurging coronavirus pandemic around, said Dr. Anthony Fauci, the nation's leading infectious disease expert.
"It does not have to be 100,000 cases a day," he told NPR on Wednesday. "I used that number because I wanted to jolt people."
During a testimony before a Congressional committee Tuesday, he said without intervention such as mask-wearing and social distancing, the US could see as many as 100,000 new Covid-19 cases a day. Already the country is seeing an average of 40,000 new cases a day.
"If you leave the virus to its own devices, it will take off on you. The control of an outbreak is what we do to oppose the dynamics of the outbreak. And if you do things that essentially enhance the outbreak, then you're part of the problem. You're not part of the solution," Fauci said.
CNN's Shelby Lin Erdman, Cheri Mossburg, Ralph Ellis and Amanda Watts contributed to this report.