What We Know About Omicron's Severity As Variant Spreads to Texas

As Omicron continues to spread around the world, scientists are discussing early data on the severity of the illness it causes.

Much attention has been paid to a report on Saturday from the South African Medical Research Council, which noted a steep rise in Omicron cases in Tshwane, Gauteng Province, described as the "global epicenter of the Omicron outbreak" by the council.

The report notes that over the previous two weeks, the majority of patients in the COVID wards at the Steve Biko/Tshwane District Hospital Complex have not been oxygen dependent. A snapshot of 42 patients from December 2, for example, showed that 70 percent were not on oxygen.

"This is a picture that has not been seen in previous waves," the report notes, stating that in the beginning of earlier waves "the COVID ward was recognizable by the majority of patients being on some form of oxygen supplementation with the incessant sound of high flow nasal oxygen machines."

The report only looks at a small number of patients and its findings have not been peer reviewed, but is being taken as a suggestion that Omicron disease severity might be lower than in other variants. Several scientists have stressed that it is still too early to say this for sure.

Dr. Anthony Fauci, chief medical adviser to the president and director of the National Institute of Allergy and Infectious Diseases (NIAID), told CNN on Sunday that "the signals are a bit encouraging" regarding the severity of Omicron but "we've really got to be careful before we make any determinations that it is less severe."

The variant has been spreading around the U.S. in recent days. It has been identified in nearly 20 states and was reported to have been found in Texas on Monday.

Dr. Emily S. Gurley, an epidemiologist at Johns Hopkins Bloomberg School of Public Health, told The New York Times recently that pre-existing immunity in South African patients could be a factor to explain why some appear to be less sick.

"We're getting more information now from South Africa, which is a particular population with a particular profile of pre-existing immunity," she said.

Several scientists have urged caution in interpreting data into Omicron's severity just yet. It is "too early to say if [it's] less virulent," tweeted Céline Gounder, clinical assistant professor of medicine at NYU Grossman School of Medicine, on Monday.

Bill Hanage, associate professor at the Harvard T.H. Chan School of Public Health, tweeted on Sunday: "The concern is that those infected and hospitalized so far are mostly young. And we would expect younger folks to have milder infections."

What's more, even if Omicron does cause less severe illness, "substantially [higher] transmission can cancel out [lower] severity," said Jerome Adams, former U.S. Surgeon General, on Sunday.

In short, although some early data does appear to suggest that Omicron causes less severe illness than other variants, scientists have warned that it is still too early to conclude that.