Coronavirus case counts have reached record highs in the United States and continue to climb. Hospitalizations have surpassed the height of the Delta wave. Deaths are just beginning to rise.
The overall pattern is familiar, but a fresh perspective on how to interpret these metrics is necessary as a faster but less severe variant tears through the country. Here’s how to think about the data in the coming days and weeks.
Case spikes show Omicron still has room to grow
In just a matter of days, coronavirus case counts have shattered previous records in the United States, as the Omicron variant spreads rapidly just about everywhere, including in communities with high vaccination rates. All but 13 states have seen record cases in the past week.
Average daily cases per 100,000 people
While these case counts are staggering, experts say they are not as alarming as they might have been a few months or a year ago. Instead, they should serve as a warning for the country, to adjust behaviors and policies to reduce infections and protect the most vulnerable.
“The circumstances have changed and we must adapt,” said Dr. Shama Cash-Goldwasser, a senior technical adviser at Resolve to Save Lives, a global health organization. “We have a less severe variant, plus many are vaccinated, but evidence suggests the vaccines are not as good at preventing infection with Omicron as they were against Delta.”
As high as the case counts are in many places, they are most certainly undercounted right now, as many Omicron infections are asymptomatic or mild and people may not know to test. Testing shortages are also limiting access, and experts say that a majority of results from popular at-home tests are not reported to public health departments.
The sharp rise in cases in many states could be followed by sharp falls, as observed in South Africa, but experts caution that the sheer volume of cases could still lead to significant numbers of extremely sick people, even from a variant that overall gives people less severe disease.
“We are going to have a lot of people sick, and even if a smaller proportion of those individuals have really horrible illnesses and adverse outcomes, it’s still a lot of people,” said Janet Hamilton, the executive director of the Council of State and Territorial Epidemiologists.
With so much risk for infection right now, public health experts say that keeping an eye on case counts and trends can encourage people to make decisions to protect themselves from infection and to avoid infecting those around them, like by getting a booster shot or wearing a mask indoors.
“We’re still in a situation that needs caution,” said Ms. Hamilton. “We’ve had a month with Omicron and there’s just still a lot we don’t know.”
Hospitalizations reveal a system under strain
Because the Omicron variant appears to cause less severe illness, hospitalization figures may tell us less about the disease and more about the strain on the health care system, which has consequences for everyone.
Hospitalizations have not yet seen the same explosive growth as cases, but this metric tends to lag case counts, and it may be too early to gauge Omicron’s full impact. What is clear is that the number of people hospitalized with Covid nationwide has already surpassed the peak of the Delta-led wave and is still rising steeply.
Hospitals, emergency rooms, urgent care centers and doctors’ offices are overburdened and understaffed across the country. Hospitals in some areas are already shutting down elective surgeries and must even treat critical care patients in emergency rooms.
And in parts of the country like the Midwest, hospitals may be in a more precarious situation — they were already under strain, having yet to recover from the Delta surge before Omicron-led illnesses began to rise.
Hospitalizations were lower and have shot up.
Hospitalizations were already high and have since increased.
Hospitalization figures are not without flaws. “National data don’t allow us to distinguish between people hospitalized because of Covid-19 and those who happened to test positive while admitted for something else,” said Jason L. Salemi, an epidemiologist at the University of South Florida, who tracks Covid data.
These “incidental patients” may be more prevalent right now because Omicron is so transmissible. Some hospitals are reporting that these patients may make up as much as half of their hospitalizations.
Dr. Salemi noted that a coronavirus infection can still exacerbate the primary illness of incidental patients; pose a risk of infection to staffers and other patients; and contribute to the overall strain on medical centers.
National hospitalization data notably does not include up-to-date measures of severe illness, such as the number of people on ventilators or their length of stay. (Federal data tracks some of this, but it is about two months behind.)
“The absence of these details about hospitalizations in the available data just muddy the water as we try to understand Omicron’s impact,” Dr. Salemi said.
Public health experts suggest monitoring Covid patients in intensive care as well as intensive care unit capacity to better gauge Covid’s impact on serious illness. About one in four U.S. hospitals with I.C.U.s recently reported that at least 95 percent of their critical care beds were full.
Death trends are not yet clear
There is hope that vaccination coverage, improved medical treatment and the milder characteristics of the Omicron variant will mean that fewer infections end in death. But the unprecedented number of cases may still lead to high levels of mortality.
“Are we going to see deaths increase? Yes, we are,” said Ms. Hamilton of the Council of State and Territorial Epidemiologists. “And they are going to go up if cases keep increasing this way.”
Experience throughout the pandemic shows it takes at least three weeks after an increase in cases to see a resulting increase in deaths, which may explain why death counts have risen only slightly so far.
Trends in deaths lag behind cases and hospitalizations by weeks because of the time it takes for people to become seriously ill and the time needed to complete and file death records. This lag varies by state and often becomes longer in times when there are more deaths, or when a case surge is overwhelming the public health system, as it is now.
Deaths can generally be predicted by looking at hospitalizations and counting backward by three weeks, suggesting that deaths will almost double in the next three weeks, said Dr. David Dowdy, an epidemiologist at the Johns Hopkins Bloomberg School of Public Health. But it's still possible that deaths will not rise as sharply as cases and hospitalizations have, he added.
“This linkage between hospitalizations and deaths is being broken as well now, as more people are getting hospitalized for milder illness,” Dr. Dowdy said. “So I actually anticipate that deaths will not reach quite that level.”
“In any case, though, in the midst of major surges,” he said, “we can't wait three weeks for data in order to act appropriately now.”