CHARLOTTESVILLE, Va. (CBS19 NEWS) -- The University of Virginia Health System says a new sub-variant of omicron is now on the rise.

It's called XBB 1.5, and it now accounts for 43 percent of all COVID cases in the United States. 

Officials say there is a discussion about whether this sub-variant should be separated from Omicron and get its own Greek letter. However, they say that due to XBB 1.5 not being significantly different from another omicron sub-variant, it will not be named after the Greek letter following omicron.

UVA Health says there's also discussion about the U.S. government shipping out more at-home COVID tests and how some of the tests may have expired by the time they arrive.

Dr. Costi Sifri suggests two things. First, check the FDA website to see if the test is still valid. Second, if you have the symptoms, take precautions until you get a better test.