When the coronavirus was in retreat across the United States in late February, the Centers for Disease Control and Prevention issued recommendations that shifted toward using the number of people hospitalized with the virus to determine the need for pandemic safety measures. That strategy will be put to the test in the next few weeks because hospitalizations are rising again nationally.
The focus veered away from depending on the number of new cases. Far more new cases than before would be required to push a community into the medium- or high-risk categories.
The change turned most of the U.S. map green at a stroke. Until then, 95% of U.S. counties were considered high-risk. But afterward, fewer than one-third of Americans were living in places in that category, the agency said.
The new guidelines gave millions of people confidence to remove their masks and recommended that as long as the pressure on hospitals remained manageable, the country could return to some version of normal life.
As of Thursday, the U.S. was averaging more than 18,000 coronavirus cases in hospitals, an increase of 20% from two weeks ago. The figure includes patients who are in the hospital because they are very ill with covid-19, as well as those admitted for other reasons who test positive on arrival.
More than half of American adults have at least one underlying chronic condition, and for many of them, the winter omicron wave was not as mild as it was for others.
Arkansas has seen a small but sustained uptick in new cases in recent weeks, though it hasn't neared the surges caused by the omicron and delta variants.
Even as daily cases have slowly risen, covid-19 hospitalizations in the state have remained relatively flat. However, the Arkansas Department of Health did report that the number of people hospitalized rose by 10 Thursday and by eight Friday.
The 58 people hospitalized in the state as of Friday compares with the peak of 1,819 on Jan. 26.
The recent influx has been even steeper in the largest high-risk area now on the national map, the hot spot that has spread across upstate New York and spilled into nearby states. According to New York state, there were 2,119 patients hospitalized in the state with covid-19 on Tuesday, 47% more than the figure from two weeks before.
The state's figure is still well below the winter omicron peak of January, when about 13,000 people were hospitalized statewide. But it has been increasing, propelled by rapidly spreading BA.2 subvariants, which were detected in central New York and have become a growing share of new U.S. cases.
In the University of Rochester Medical Center system, which includes six hospitals in the Finger Lakes region and western New York, coronavirus hospitalizations have quadrupled in recent weeks, rising to about 200 patients from a low of about 50 in early April, according to Chip Partner, a spokesperson for the hospital system.
Most of those patients were in the hospital for other reasons, such as surgery, but tested positive when they were admitted, Partner said, adding that relatively few covid-19 patients have needed intensive care recently.
At the same time, staffing shortages at hospitals in the region have been compounded by a recent increase in infections among their staffs. At F.F. Thompson Hospital in Canandaigua, N.Y., 45 of the hospital's 1,750 workers were out with the virus recently, and there are 252 unfilled job openings.
"Covid is here. Covid is an issue, but the main challenge up here is the staffing," said Michael Stapleton, the hospital's CEO.
Other hot spots are also putting pressure on health care systems. In Puerto Rico, 245 people on the island were in hospitals this week with the virus, more than five times the caseload from a month ago.
Although hospitalizations generally lag behind the trends in new cases, they remain among the most reliable kinds of data about the pandemic, experts agree -- much more so than official reports of positive test results, which experts say significantly understate the true number of infections, especially with the rise of at-home testing.
As of Thursday, the average number of new confirmed U.S. cases was almost 68,000 a day, nearly a 60% increase over the past two weeks, according to a New York Times database. Hospitalizations are reported fairly rigorously.
"For hospital data, even given that all the people were not admitted because of covid, we can be sure that the numbers are pretty accurate," said Dr. Eric Toner, a senior scholar at the Center for Health Security at the Johns Hopkins Bloomberg School of Public Health. "So it's the best data source we have now. The number of new covid admissions is the number that I pay the most attention to."
About 11% of people hospitalized with coronavirus infections in the United States were in intensive care as of Wednesday, according to federal data.
The CDC is also keeping a close eye on the nature of hospitalizations.
"We're seeing less oxygen use, less ICU [intensive care unit] stays and we haven't fortunately seen any increase in death associated with them," compared with earlier periods of the pandemic, Dr. Rochelle Walensky, the CDC director, said last week.
While the criteria for declaring a county to be at high, medium or low risk have changed, the threat that the virus and its new variants pose has not. Most experts say everyone should continue to be tested frequently if they are mixing in large groups and people who are vulnerable should consider continuing to wear masks in indoor public settings, even if they are not required.
This week, the CDC restated its recommendation that travelers wear masks in airplanes and airports, and on trains and buses, even though a judge struck down a federal mask mandate for public transportation last month.
Dr. Ashish Jha, the new White House coronavirus response coordinator, was asked Friday on the "Today" show about rising cases and the end of the mask requirement on airplanes. While maintaining the mandate "would've been helpful," he said, citing the highly contagious BA.2 subvariant as "the primary driver" of rising infections.
"The only way to slow the surge is to test and isolate if positive," said Mara Aspinall, an expert in biomedical diagnostics at Arizona State University.
That would help stave off a looming problem for medical workers.
"Another surge of hospitalizations would be extraordinarily difficult," Toner said.
Information for this article was contributed by Adeel Hassan and Sharon Otterman of The New York Times and by Hunter Field of the Arkansas Democrat-Gazette.