As Omicron Rages, How Important Are Case Counts Anymore?
The record-breaking numbers surrounding the Omicron surge are dizzying, with so many Americans falling prey to the highly infectious COVID-19 variant.
The United States reported more than 1.3 million COVID cases on Monday, the highest daily total recorded for any country in the world. The seven-day case average has tripled in two weeks, reaching more than 700,000 new infections every day.
But that statistic may be less important than another record: That more than 142,000 Americans are currently hospitalized with COVID, a number that's doubled in three weeks and itself represents another all-time high.
Some public health experts are making the case that, when it comes to assessing the threat from the pandemic, COVID-related hospitalizations are now a much more valuable marker than overall case counts.
That's because vaccines have reduced the risks of severe COVID, making it harder to interpret the threat of a COVID surge through case counts alone. That's particularly true in the face of the Omicron variant, which is as infectious as measles but tends to cause less severe illness than the Delta variant did.
"I've always said hospitalizations are the most important metric when it comes to COVID. That is even more the case with an immune-escape variant like Omicron," said Dr. Amesh Adalja, a senior scholar with the Johns Hopkins Center for Health Security in Baltimore. "The goal has never been to eliminate COVID -- that's not biologically possible -- but to tame it, decoupling cases from hospitalizations."
Hospitalizations represent "the illnesses we're principally trying to prevent," said Dr. William Schaffner, medical director of the National Foundation for Infectious Diseases.
"That's where all the tragedy is. That's where the agony for the patient and the patient's family is. That's where the stress on the health care system is, primarily. And frankly, that's where a lot of the costs are. Hospitalizations are very, very expensive," Schaffner added.
Home test results are hidden
To further muddy case counts, the advent of home test kits means that many positive cases will never get reported to officials keeping COVID stats, Schaffner noted.
"Previously, virtually all of the testing was being done at controlled locations, and so the information on the number of tests and the proportion of positive results all went into state health department databases," Schaffner said. "Those data were pretty accurate."
But now, people can buy over-the-counter COVID test kits to test themselves, and those results aren't reported to anyone. The true number of infections is likely much higher than the reported case counts because positives from at-home tests aren't included in the official tally.
"My family has done any amount of at-home testing, and that's not reported -- either the number of tests or the results," Schaffner said. "Those data, in terms of numbers, are not nearly as accurate as they were."
That's not to say case counts are worthless, Schaffner hastened to add.
The proportion of positive tests -- the number of overall tests reported that are actual infections -- are useful "in a general public health way," Schaffner said.
"Think of it as standing back and looking at the mountain in the distance, and you can see where things rise and where things fall," Schaffner explained. "You can get a general sense of what's going on."
Sorting out hospital numbers
If the proportion is still high in your region, "then, by George, you know the virus is out there infecting a lot of people," Schaffner continued. "If it starts to drop in a sustained way, well, you can take some comfort in that. If eventually it gets down to less than 5%, which is the goal, then we can all take a deep breath."
COVID hospitalization data has its issues as well.
The numbers include people who test positive for the coronavirus after being admitted for other conditions, so some patients might have been admitted for some cause other than COVID-19. There's no national database showing the actual number of patients hospitalized specifically for COVID.
But at this point, the hospitalization numbers are being gathered in a much more diligent way than testing data, and are secure enough to have meaning, Schaffner said.
Hospitalizations involving COVID have been "always very rigorous data," Schaffner said. "We've been testing people who are admitted to the hospital in a very sustained way. Those data are going to continue to remain very secure, along with deaths."
Overall, the data at this point indicates that the Omicron variant is "less apt to cause hospitalization, and when you're in the hospital you're less sick," Schaffner said. "You're less apt to need intensive care unit admission and you're less apt to need ventilation assistance. People are saying that we can get these people out of the hospital faster than we used to be able to.
"That's consistent with the laboratory data which indicate that Omicron is very effective at infecting the cells in the upper airway, in the throat and behind the nose, but is not very efficient in infecting lung tissue," Schaffner noted. "Clearly the ability to really infect the upper airways is related to contagiousness, because we shed more virus, therefore we spread it around more readily and are more apt to infect people around us."
The U.S. Centers for Disease Control and Prevention has more about COVID-19.
SOURCES: Amesh Adalja, MD, senior scholar, Johns Hopkins Center for Health Security, Baltimore; William Schaffner, MD, medical director, National Foundation for Infectious Diseases