Serum neutralization of SARS-CoV-2 Omicron BA.2, BA.2.75, BA.2.76, BA.5, BF.7, BQ.1.1 and XBB.1.5 in individuals receiving Evusheld

Abstract

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant is undergoing continuous evolution and convergent mutation. These new subvariants are raising concerns that they may evade neutralizing monoclonal antibodies (mAbs). We investigated the serum neutralization efficacy of Evusheld (cilgavimab and tixagevimab) against SARS-CoV-2 Omicron BA.2, BA.2.75, BA.2.76, BA.5, BF.7, BQ.1.1, and XBB.1.5. A total of 90 serum samples from healthy individuals were collected in Shanghai. Anti-RBD antibodies were measured and symptoms of infection with COVID-19 were compared among those individuals. The neutralizing activity of serum against Omicron variants was analyzed by pseudovirus neutralization assays in 22 samples. Evusheld retained neutralizing activity against BA.2, BA.2.75, and BA.5, albeit with somewhat reduced titers. However, the neutralizing activity of Evusheld against BA.2.76, BF.7, BQ.1.1, and XBB.1.5 significantly decreased, with XBB.1.5 showing the greatest escape activity among the subvariants. We also observed that Evusheld recipients displayed elevated antibody levels in their serum, which efficiently neutralized the original variant, and exhibited different characteristics of infection than those who did not receive Evusheld. The mAb has partial neutralization activity against Omicron sublineages. However, the increasing doses of mAb and a larger size of population should be further investigated.

Keywords: COVID-19; SARS-CoV-2; monoclonal antibodies; receptor-binding domain; variants.