Omicron and its sublineages' now 10-month influence likely won't recede anytime soon, one expert predicts.
When the original omicron variant was first detected in the U.S. in early December, it made a swift rise to dominance, accounting for more than 70 percent of COVID-19 cases by Dec. 18. In January, it pushed daily cases to record levels of more than 800,000. Since then, omicron has developed a family of sublineages, the latest being the highly transmissible BA.5, which now accounts for 85 percent of cases, according to the CDC's Aug. 2 variant proportion estimates update.
"I suspect we are going to be in omicron land for some time, probably at least until the fall," Jonathan Abraham, MD, PhD, infectious diseases physician at Boston-based Brigham & Women's Hospital, told Becker's. He is also an assistant professor of microbiology at Harvard Medical School and runs the Abraham Lab, which studies how pathogens interact with the cells of their hosts.
Omicron represents a large evolutionary leap from the ancestral coronavirus strain and is harder for the immune system to recognize, helping to explain why the variant has sustained its dominance longer than others. The earlier Greek alphabet of variants we've seen (alpha, beta, delta, gamma, etc.) only had a handful of mutations, and when omicron came along it had what Dr. Abraham called a "bucket full of mutations." And omicron's family of sublineages — from BA.1 to BA.5 — have only further increased the number of mutations. All of this makes it more difficult for an entirely new variant to outcompete the long-reigning variant.
Essentially, omicron and its children have evolved in a way that they "could outcompete pretty much anything else that is out there in terms of transmission," in a population that now has some degree of immunity from prior infection and vaccination, he said.
"I think the only way omicron will disappear is … to be outcompeted by something drastically different from omicron," like what happened to the original strain when omicron appeared, Dr. Abraham said.
That would require something with a "much larger number of mutations" and then over time, like omicron, evolve its own set of sublineages. "Until that happens, it's unlikely omicron will be replaced," he said.
It's not out of the realm of possibility that omicron will be the last major variant of concern, with its sublineages eventually teetering away. As with any pandemic predictions though, Dr. Abraham was cautious in that message.
"Every time we've made a prediction of a variant being the last variant, like we [thought] with delta, we've been surprised," he said.