LAUSR

New sub-lineages of the SARS-CoV-2 omicron variants with enhanced ability to evade existing antibody responses continue to evolve. A better understanding how susceptible emerging virus variants are to immunity induced by vaccination or infection could help predict which strains will become dominant going forward. Here we evaluate neutralizing antibodies against several clinical isolates of omicron variants including BQ.1.1 and XBB in sera from 3x mRNA vaccinated individuals and individuals with breakthrough infections with early (BA.1 or 2) or late (BA.5) omicron variants. In addition, we evaluate neutralizing antibodies in serum samples harvested from 32 individuals from the middle of October 2022, to provide a more recent estimate of immunity. As expected, serum samples harvested after breakthrough infections were more efficient at neutralizing all the omicron variants, compared to sera from non-infected individuals. While neutralization remained high against variants such as BA.2.75.2, BR.1 and BF.7, there was a marked reduction in neutralizing titers against BQ.1.1 and XBB. Similarly, most serum samples harvested in October 2022 had very low neutralizing antibodies against BQ.1.1 and XBB, suggesting that these variants and their descendants will dominate infection waves in Norway this winter season.