But by the looks of packed holiday crowds this weekend, many Americans don't care -- threatening to infect others and set the economy back even further.
"We are in free fall," said Dr. Rochelle Walensky, chief of infectious diseases at Massachusetts General Hospital.
"You see the footage of what happened this past weekend. And people are either naive to the influence of their actions, or they're simply resigned to ignore it."
This virus is notorious for how contagious it is -- and how easily people can infect others without symptoms.
"We know of the 50,000 cases this past day -- a single day of this (holiday) weekend," Walensky said. "If they're young people, it could be 500 people who die from that. If they're older people, it could be 7,500 people who die from that -- just from a single day of infection."
But "even if a person does not get harmed individually, they have the potential to infect two to three other people who will be harmed by this infection. So there's a lot of harm that could be done."
Almost 3 million Americans have been infected with Covid-19, including a growing number of young adults. More than 129,000 Americans have died from Covid-19, and some survivors are grappling with long-term complications.
"Let's remember there are 300 million people in this country who remain susceptible and have been uninfected so far, and this virus is far from running out of people to infect," Walensky said.
"And until we change our behavior to prevent these infections, the infections are going to continue to soar."
In 32 states, the rates of infection are still going up
With spikes in new cases, doctors are worried about more hospitalizations and deaths in the coming weeks.
"We're accelerating nationally. ... The number of cases still continues to accelerate," said Dr. Peter Hotez, dean of the National School of Tropical Medicine at the Baylor College of Medicine in Houston.
"We're breaking records almost every day here in the state of Texas. People are piling into hospitals, into ICUs (intensive care units). We can't really keep going at this rate," he said.
"And it's not only happening in Texas, of course. It's happening in Florida, Arizona. We're starting to see now a similar situation unfold on the Gulf Coast. And now we're starting to see this in the Upper Midwest and in Tennessee as well."
Like Walensky, Hotez described the spiraling situation as a "free fall."
At least 32 states are reporting higher rates of new cases this week compared to last week, according to Johns Hopkins University data: Alabama, Alaska, Arizona, California, Delaware, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Louisiana, Maryland, Michigan, Missouri, Montana, Nevada, New Mexico, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, South Carolina, Tennessee, Texas, Washington, West Virginia and Wisconsin.
In 14 states, the rates of new infections are generally holding steady: Arkansas, Colorado,
