(NEXSTAR) – On Nov. 26, 2021, the World Health Organization gave omicron its name, designating it a “variant of concern.” It was the day after Thanksgiving, and the first omicron-caused case of COVID-19 had just been confirmed in the U.S.

One month later, on Christmas, nearly 200,000 new cases were being confirmed daily. On Jan. 3, more than a million people tested positive, and the U.S. found itself in the biggest COVID-19 surge of the pandemic’s history.

Nearly a year after omicron first landed in America, we have seen sublineages of omicron spread left and right – BA.2, then BA.4 and BA.5, now even XBB. But we have yet to see a variant arise deemed concerning enough to earn a Greek letter for a name.

“That’s good news,” said Dr. Monica Gandhi, a professor of medicine and infectious disease expert at the University of California, San Francisco.

Gandhi said so many people have been vaccinated, so many have been infected, and a lot of people have had both. “So that’s called hybrid immunity. When the population is so much more immune, the virus can make minor shifts in an immune population, but it can’t make major shifts.”

The next variant, if and when it should arise (and scientists believe it will someday), would be named pi, the letter after omicron in the Greek alphabet.

While natural immunity and widespread vaccination slow down the virus’ ability to mutate, there are still two major ways the coronavirus can continue to evolve, and potentially create pi.

It could emerge from the animal kingdom, for example. While there are few documented cases of animals spreading COVID to humans, the fact that animals can catch the virus means it can continue to mutate as it jumps from host to host.

The virus has also been shown to mutate more quickly inside the bodies of immunocompromised people who can struggle with prolonged illness from COVID-19. Those long infections give the virus more time to replicate and make “rapid, multistage evolutionary jumps,” a study published in the New England Journal of Medicine found. Any major mutation of the virus could turn into a new variant.

If a new type of coronavirus does arise, and it’s more contagious or better at evading existing immunity, we’d expect it to start to edge out omicron, much like omicron did to delta last year.

In the meantime, we should “feel lucky” we haven’t seen that happen yet, Gandhi said. It’s one thing that could help us avoid a massive surge this winter – unless we get bad news on Thanksgiving again.