Antigenic characterization of SARS-CoV-2 Omicron subvariants XBB.1.5,BQ.1,BQ.1.1,BF.7 and BA.2.75.2

Dear Editor,Recently,a number of new Omicron subvariants related to BA.4/5 and BA.2.75 have emerged and shown remarkable antibody evasion capacities,in particular BF.7,BQ.1,BQ.1.1,BA.2.75.2,XBB and XBB.1.5.1 Unsurprisingly,these new subvariants are quickly gaining prevalence worldwide.In fact,some of them have outcompeted BA.5 in the USA according to CDC’s national genomic surveillance data in which,as of 6th February 2023,XBB.1.5,BQ.1.1,BQ.1,XBB and BF.7 have achieved a dominance of 66.4%,19.9%,7.3%,2.3%and 0.5%in the USA,as compared to 0.5%for BA.5.In this report,using plasma samples collected from individuals following different vaccination strategies and COVID-19 convalescent donors,we performed pseudoviral neutralization assays to confirm severe reductions in neutralization titers against BF.7,BQ.1,BQ.1.1,BA.2.75.2,XBB and XBB.1.5 in comparison to other Omicron sub-lineages.XBB and XBB.1.5 were shown to be remarkably resistant to plasma neutralization in all tested cohorts.By comparing the differential neutralization profiles,we found that a heterologous booster with an aerosolized vaccine following 2 doses of inactivated vaccine seemed to be superior to other vaccination strategies.