Without the measures in place, some states may see a jump in cases, leading to more deaths than predicted, health experts have said.
"There are some states, some cities, or what have you, looking at it and kind of jumping over the first checkpoint. And I obviously mean you could get away with it, but you pose a very significant risk," Fauci said during CNN's coronavirus town hall Thursday night. "I hope they can actually handle any rebound they see."
Experts have warned of the dangers of reopening a country that has test shortages, which they have called crucial to return to normal life.
Other states impose new restrictions
"We need to spend time remaining vigilant," Louisiana Governor John Bel Edwards said Thursday after expanding the state's order through May 15.
Some of the measures the governors have taken include:
- Georgia government Brian Kemp had some businesses open last week. He said he would not extend a state-of-the-home order, and would require businesses to operate with strict social distance measures before May 13.
- California Govin Newsom ordered beaches and parks closed, and said the reopening of schools and businesses is weeks away.
- Arizona Governor Doug Ducey extended the order-to-home by May 15.
- Florida has two different approaches within its boundaries: Restaurants and stores can let customers come in, with reduced capacity, from Monday. But not in South Florida's populous Palm Beach, Broward and Miami-Dade counties, home to 6 million people.
- West Virginia dentists were allowed to work back Thursday while the restaurants, churches and other services such as lounges have to wait until Monday.
Another two years of pandemic misery predicted
Coronavirus is likely to continue to spread for another 18 months to two years – until a majority of the world's population has been infected, a team of pandemic experts predicted Thursday in a new report.
"This thing won't stop until it infects 60 to 70% of people," said Michael Osterholm, who heads the Center for Infectious Disease Research and Policy at the University of Minnesota. "The idea of doing this soon defies microbiology."
Osterholm has been writing about pandemics for 20 years and served as advisor to several presidents. He said it will take almost two years for the herd of immunity to gradually develop among people.
An effective vaccination is still months away
There are 102 potential coronavirus vaccines in development around the world, according to the World Health Organization. The US National Institutes of Health were among the first to begin human trials.
Doctors testing experimental coronavirus vaccines can look for local infection clusters to try out potential immunizations, Fauci said.
"If we get in there and there are a number of infections, you can get an efficiency signal right away, which means you may know in advance whether you have something that works or not," Fauci said.
When the first phase of safety testing shows that the vaccine is safe, possibly in the summer, the second and third phases of testing can begin, he added.
With this approach to testing, the United States can invest "hundreds of millions of dollars" to begin developing a vaccine, even before scientists prove it works.
"You don't have to wait for five or six months to scale up to get enough doses, to provide a meaningful number of people," Fauci said. "It's a risky financial circumstance, but it's definitely worth the risk given what's at stake."
Provided the vaccine is safe, effective and can be produced quickly, it may be available in January, but it is not guaranteed, he said.
Many things can go wrong when we test a vaccine, including complications for those who received the vaccine when exposed to the virus, Fauci said.
CNN's Jay Croft, Jamiel Lynch and Elizabeth Cohen contributed to this report.