Comparable immune escape capacity between KP.2 and other SARS-CoV-2 variants in the central Chinese population after the first COVID-19 booster.

The neutralisation ability of homologous and heterologous booster vaccinations against the KP.2 variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is unknown. Therefore, we aimed to evaluate the neutralisation of the Omicron variants by comparing serum samples from Chinese individuals who received heterologous boosters (from different manufacturers) with those who received homologous boosters (from the same manufacturer) against SARS-CoV-2. We collected serum samples from participants in the homologous (n = 38) and heterologous booster groups (n = 38) over 690 days. Serum pseudo virus neutralisation was tested against the prototype, XBB.1, JN.1, and KP.2 variants to detect neutralisation titres. An enzyme-linked immunosorbent assay was used to measure the total concentration of neutralising antibodies against the receptor binding domain of SARS-CoV-2. Neutralisation assays revealed 12.3-, 12.3-, and 11.4-fold reductions against JN.1, KP.2, and XBB.1 variants, respectively, compared with that against the prototype. However, no significant difference was observed in neutralising antibody titres among the JN.1, KP.2, and XBB.1 Omicron variants. Additionally, homologous boosters and men produced fewer neutralising antibodies compared to heterologous boosters and women. Thus, our results demonstrate that the Omicron variant KP.2 exhibits similar evasion properties to those observed in other variants.