Immune evasion after SARS-CoV-2 Omicron BA.5 and XBB.1.9 endemic observed from Guangdong Province, China from 2022 to 2023.

Background: From 2022 to 2023, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused by Omicron variants spread rapidly in Guangdong Province, resulting in over 80% of the population being infected.

Results: To investigate the levels of neutralizing antibodies (NAbs) in individuals following the rapid pandemic and to evaluate the cross-protection against currently circulating variants of SARS-CoV-2 in China, neutralization assay and magnetic particle chemiluminescence method were used to test the 117 serum samples from individuals who had recovered 4 weeks post-infection. The results indicated that the levels of NAbs against prototype and Omicron variants BA.5 were significantly higher than those against Omicron variants BQ.1, XBB.1.1, XBB.1.9, XBB.1.16 and EG.5, regardless of whether the infection was primary or secondary.

Conclusions: The cross-protection provided by NAbs induced by prototype and Omicron BA.5 variants was limited when challenged by BQ.1, XBB.1.1, XBB.1.9, XBB.1.16 and EG.5 variants. This indicates that we should pay more attention to the risk of multiple infection from any novel Omicron variants that may emerge in the near future.