(Reuters) -The U.S. Centers for Disease Control and Prevention estimated on Friday that Omicron subvariants BQ.1 and BQ.1.1 account for nearly half of the COVID-19 cases in the country for the week ending Nov. 19, compared with 39.5% in the previous week.
The proportion of the two variants, which are descendants of Omicron's BA.5 sub-variant, have risen to 49.7% of circulating coronavirus variants, around two months after they were initially detected.
BQ.1.1 made up nearly of 24.2% of circulating variants and BQ.1 was estimated to make up 25.5% of circulating cases in the week of Nov. 19, the U.S. CDC said.
There is no evidence yet that BQ.1 is linked with increased severity compared with the circulating Omicron variants BA.4 and BA.5, the European Centre for Disease Prevention and Control said, but warned it may evade some immune protection, citing laboratory studies in Asia.
New variants are monitored closely by regulators and vaccine manufacturers in case they start to evade protection offered by current shots.
The BA.5 subvariant that drove the COVID-19 cases earlier in the year is estimated to make up 24% of cases, compared with nearly 33.8% in the week ended Nov. 12.