'Escape variants' gain traction in US

The days of the orderly succession of individual dominant variants (alpha, beta, delta, etc.) are likely over, with the next phase of the COVID-19 pandemic to be marked by the splintering of a single strain, or what experts call "convergent evolution." Right now, that's exactly what's happening with omicron, Yahoo News reported Oct. 13.

Omicron subvariants are competing for dominance in different corners of the world. Of the dozens being tracked, the U.K. Health Security Agency has identified BA.2.75.2, BF.7 and BQ subvariants as the most concerning due to their growth advantage over other strains and their ability to evade immunity, according to an Oct. 7 report.

BA.5 remains dominant in the U.S., though its prevalence is quickly falling. CDC variant proportion estimates show the strain accounted for 67.9 percent of cases for the week ending Oct. 15. Meanwhile, BA.4.6 has grown to account for 12.2 percent of cases, while BF.7 accounts for 5.3 percent. On Oct. 15, the agency began tracking BQ.1.1 and BQ.1, which each account for 5.7 percent of cases. 

The BQ.1 and BQ.1.1 pair have been dubbed "escape variants," because of their ability to essentially dodge immunity. They are thought to completely resist existing monoclonal antibody drugs. In an Oct. 13 tweet, Eric Feigl-Ding, PhD, epidemiologist and former faculty member at Boston-based Harvard Medical School, described the strains as "two of the most evasive variants known to date." The good news is that the updated omicron boosters are believed to offer protection against the strains, since they're descendants of BA.5, he said.

"So where does this sudden BQ.1 and BQ.1.1 mess put us? Our models predict a variety of 5+ key mutation subvariants will cause a surge of COVID by mid to late November just in time for Thanksgiving, especially if we don't BA.5 bivalent boost," Dr. Feigl-Ding wrote.  

Cases are already rising in some European countries, including the U.K. As of Oct. 8, positive COVID-19 tests were up 21.1 percent over the previous seven days, national data shows. Cases are still down in the U.S., though experts say signs of a winter surge are growing. 


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