(CNN) -- Loosening restrictions and increasing public gatherings may make it seem as though the worst of the Covid-19 pandemic is over, but just this week Florida, Texas and Arizona set daily records for new cases.
The states are among 21 across the nation seeing increasing trends in new cases from one week to the next. More than 2 million people in the US have been infected with coronavirus and 116,962 have died, according to data from Johns Hopkins University. Health experts are warning that more infections and deaths are in store as states continue their reopening plans.
"We may be done with the pandemic, but the pandemic is not done with us," Dr. Ashish Jha, director of the Harvard Global Health Institute, said Tuesday.
Florida recorded almost 2,800 new coronavirus cases on Monday -- the highest number of new and confirmed cases in a single day the state has seen, according to the Florida Department of Health. Despite the increase, Gov. Ron DeSantis told reporters Tuesday that the state will not shut down.
"We're going to go forward. We're going to continue to protect the most vulnerable," DeSantis said. "We're going to urge, continue to advise, particularly our elderly population to maintain social distancing, avoid crowds."
Arizona reached a record-high daily number of cases on Tuesday, as did Texas.
Texas Gov. Greg Abbott attributed the increase to an outbreak at an assisted living facility and delayed reporting.
But the state's hospitalization rate, a number officials monitor to ensure the healthcare system isn't overwhelmed, has been increasing as well.
Nationwide reopenings coupled with the flouting of personal safety measures has led researchers at the Institute for Health Metrics and Evaluation (IHME) at the University of Washington to increase their projections of Covid-19 deaths this summer.
"Unless we are effective at other things like wearing a mask, avoiding contact, it's going to pretty inexorably lead to the second wave," IHME Dr. Chris Murray told CNN's Anderson Cooper.
How states are trending
- 21 states are seeing upward trends in newly reported cases from one week to the next: Alabama, Alaska, Arizona, Arkansas, California, Delaware, Florida, Georgia, Hawaii, Kansas, Oregon, Louisiana, Montana, Nevada, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, West Virginia and Wyoming.
- 8 states are seeing steady numbers of newly reported cases: Connecticut, Indiana, Maine, Mississippi, Ohio, South Dakota, Utah and Washington.
- 21 states are seeing a downward trend: Colorado, Idaho, Illinois, Iowa, Kentucky, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Nebraska, New Hampshire, New Mexico, New Jersey, New York, North Dakota, Pennsylvania, Rhode Island, Vermont, Virginia and Wisconsin.
- One state, Vermont, has seen a decrease of at least 50%.
The second wave may be coming, but we aren’t out of the first yet
Early on, it looked as though the finish line for the pandemic was the end of summer. And even though experts no longer see that as the case, many Americans are eager to return to a sense of normalcy.
Murray expects a "second wave" to begin late August, with the US reaching more than 201,000 coronavirus deaths by October 1.
But rates of coronavirus cases in the US haven't yet dropped to a level low enough to call the first wave over.
As the virus spreads, it appears to be following highways, researchers from Children's Hospital of Philadelphia and the University of Pennsylvania said Tuesday.
People are leaving their homes now that more places are opening. As more people interact with others, the disease spreads, the researchers found.
Navajo Nation institutes lockdowns
The Navajo Nation, which surpassed New York and New Jersey for the highest per-capita coronavirus infection rate in the US, announced weekend lockdowns on Tuesday that are intended to reduce infections.
The first is expected Friday to Monday, and the next will take place the following weekend, according to the release.
"We have to keep doing what we're doing by wearing protective masks, complying with the weekend lockdowns, staying home, and maintaining a six-foot distance from others. Now is not the time to back down. Let's not back down! Wear your masks, practice social distancing, and wash your hands," said Navajo Nation President Jonathan Nez in a news release.
The Navajo Nation spans parts of New Mexio, Utah and Arizona, which has seen a large increase in new cases. The Native American territory reported a population of 173,667 on the 2020 census.
Texas mayors want mandatory masks to mitigate the spread
Nine Texas mayors, including the top officials in Houston, Dallas, Austin and San Antonio, have urged the state's governor to require face masks to stop the virus from spreading in their cities.
"If mayors are given the opportunity to require face coverings, we believe our cities will be ready to help reduce the spread of this disease," the mayors said in a letter to Abbott.
New research supports the case for wearing masks to reduce spread.
In a study reported Tuesday, researchers estimated between 230,000 and 450,000 cases of the virus were prevented in the states that enacted requirements for mask use between April 8 and May 15.
"The findings suggest that requiring face mask use in public might help in mitigating COVID-19 spread," wrote Wei Lyu and George Wehby, with the Department of Health Management and Policy at the University of Iowa's College of Public Health.
Also in hopes of mitigating spread, the nonprofit Resolve to Save Lives headed by former US Centers for Disease Control and Prevention Director Dr. Tom Frieden released a new contact tracing playbook Tuesday.
The guide will supplement CDC efforts to give local public health departments detailed guidance on how they can keep the virus from spreading further.