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. We evaluated Omicron variants (XBB.1, JN.1, and KP.2) neutralisation in participants vaccinated with heterologous versus homologous boosters. In 38 participants each from homologous and heter-ologous booster groups over 690 days, serum pseudovirus neutralisation was tested against the prototype, XBB.1, JN.1, and KP.2 variants to detect neutralisation titres. Total concentration of neutralising antibodies against SARS-CoV-2 receptor-binding domain was measured by en-zyme-linked immunosorbent assay. On throat swab samples, reverse transcription polymerase chain reaction was used to verify breakthrough SARS-CoV-2 infections in participants. Geometric mean neutralising titres against the prototype, total, XBB.1, JN.1, and KP.2 variants were 488.3, 54.5, 42.9, 39.7, and 39.8, respectively. Neutralisation assays revealed 12.3-, 12.3-, and 11.4-fold reduc-tions against JN.1, KP.2, and XBB.1 variants, respectively, compared with the prototype. No sig-nificant difference occurred in neutralising antibody titres among JN.1, KP.2, and XBB.1 Omicron variants. Homologous booster group and males produced fewer neutralising antibodies than heterologous booster group and females, respectively. KP.2 Omicron variant exhibited compa-rable immune evasion properties with other variants. A second different-type or broad-spectrum booster may improve neutralisation against Omicron variants KP.2.