By October 29, 2022, two Omicron offshoots called BQ.1 and BQ.1.1 made up 27% of infections in the United States. A week or so earlier, National Geographic had put their share at just over 10 percent. Both descend from BA.5, the variant that had run the pandemic for months.
They were not confined to America. Europe’s disease agency, the ECDC, labeled BQ.1 a variant of interest after cases turned up in the UK and several other European countries, and Canada detected them in wastewater. The agency’s modelling expected the pair to cause more than 50% of infections sometime between mid-November and the start of December 2022, and more than 80% of cases by early 2023.
Why they spread
The agency’s reading was that the growth came mostly from immune escape, meaning the virus slips past antibodies left by earlier infection or vaccination. Both subvariants carry spike mutations, among them K444T, N460K, L452R and F486V, and BQ.1.1 adds R346T. Stuart Ray, an infectious disease specialist at Johns Hopkins, noted that unrelated lineages had landed on changes in the same stretch of the spike. He called it convergent evolution: separate lines arriving at the same answer to the same problem.
John Swartzberg of the University of California, Berkeley, was blunt about the pace. “Within a few weeks, things could look upside down,” he said. One tally circulating on social media suggested BQ.1.1 had multiplied eight-fold in 19 days, going from five sequences to 200.
What protection is left
The reassuring part is about severity. Researchers writing in The Conversation found no evidence that BQ.1 caused worse illness than BA.4 and BA.5, and National Geographic likewise reported little sign of more severe disease. Vaccines and past infection do not fully block infection or reinfection, and a preprint suggested immunity from earlier Omicron strains might not offer broad cover against BQ.1.1. Even so, the Conversation’s author concluded that the shots should keep offering firm cover against serious illness and death.
Ray added a caution. Comparing severity with earlier waves is hard because immunity in the population has changed, and these strains might have done far more damage had they arrived before vaccines. “If people don’t keep their immunity up through vaccination, then we may see increasing levels of severity,” he said. The updated bivalent booster, aimed at BA.4 and BA.5, was the tool health officials were pointing people toward, though no human data yet showed how well it worked against the new strains.
Treatment is another worry. A preprint suggested BQ.1.1 might resist Evusheld, the antibody therapy given to people whose immune systems respond poorly to vaccines, and Anthony Fauci told CBS News the subvariant seemed to elude important monoclonal antibodies.
Sources
- Omicron BQ.1 and BQ.1.1 – an expert answers three key questions (The Conversation)
- Why Omicron subvariants BQ.1 and BQ.1.1 are poised to take over in the U.S. (National Geographic)
