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(NEXSTAR) – The U.S. is currently in the grips of the latest COVID-19 variant, and many experts believe it won’t be the last before the end of the pandemic.

Omicron, designated as a variant of concern (VOC) by the World Health Organization, has all but pushed delta to the side, at least as far as sequencing efforts in the U.S. are suggesting. But viruses are constantly mutating, and a widespread virus — like the one that causes COVID-19 — has a better chance of gradually evolving from host to host and producing concerning variants.

Davidson Hamer, a professor of Global Health and Medicine at the Boston University’s Schools of Public Health and Medicine, told Nexstar that one of the potential mechanisms for the creation of a new variant concerns the animal population.

“Because [the virus that causes COVID-19] can infect certain animals — some very well, like mink or white-tailed deer — the virus could go into an animal, reassort and pop back out into the human population,” Hamer said.

“That could be a potential mechanism by which a new variant might arise, and a very worrisome possibility,” he added.

Another potential avenue that epidemiologists have identified involves immunosuppressed, or immune-deficient human patients who become chronically infected with the virus, but do not succumb to it.

“People who are immunosuppressed have a harder time clearing the virus from their bodies, and many mutations may accumulate in a single person and then be transferred to others,” explained Jorge Salinas, an assistant professor of infectious diseases at Stanford University.

Experts also say this mechanism — incubating in a chronically sick patient — is thought to be the avenue by which the omicron variant and its numerous mutations came about.

Researchers say it’s difficult to predict where and when a new variant will emerge. And when they do, it doesn’t always mean the variant is better adapted to spread. There is always the possibility, however, that one of the variants could transmit better, or be more severe, or have properties that make it better at evading immunity or become less responsive to current therapies.

George Rutherford, an epidemiologist at the University of California, San Francisco, likened a virus’s mutations to “typos,” some of which are more harmful than others.

“If viral evolution were logical, which it is kind of, we would expect … the variants that would survive and thrive would be more transmissible or more immune evasive,” said Rutherford. But there’s also “no premium” for a virus to kill off its host immediately, he said, as that wouldn’t be an efficient way for the virus to spread.

Rutherford warned, however, that virus mutations won’t always follow the most logical path.

“Be prepared,” he said. “The [next mutation] could be something that’s very different.”