The omicron subvariants that have become dominant in recent months present a serious threat to the effectiveness of the new boosters, render antibody treatments ineffective and could cause a surge of breakthrough infections, according to a new study.
The BQ.1, BQ.1.1, XBB and XBB.1 omicron subvariants are the most immune evasive variants of Covid-19 to date, according to scientists affiliated with Columbia University and the University of Michigan.
The immune response of people who were vaccinated and had breakthrough infections with prior omicron variants was also weaker against the subvariants.
For people who received the omicron boosters, antibodies that block infection were 24 times lower against BQ.1, 41 times lower against BQ.1.1, 66 times lower against XBB and 85 times lower against XBB.1 compared to their performance against the ancestral strain that emerged in Wuhan, China in 2019.
BQ.1.1 and BQ.1 represent 37% and 31% of new infections respectively, while XBB is causing 4.7% of new infections, according to CDC data.