Cross-reactive immunogenicity against other Omicron sub-variants
SARS-CoV-2 Omicron variant evolves rapidly, and many sub-variants have emerged. Owing to its higher transmissibility and immune-evasive capability, Omicron BA.2 replaced BA.1 quickly, and was soon replaced by BA.4 and BA.5 afterwards. Currently, BA.4 and BA.5 have become the dominantly circulating variants worldwide. Besides Omicron BA.1.1, the cross-reactive immunogenicity of NVSI-06-09 against BA.2, BA.4, and BA.5 was also evaluated by using the live-virus microneutralization assay. The nAb responses against these three Omicron sub-variants were tested in all participants in PPS, and compared between the NVSI-06-09 and BBIBP-CorV booster groups.Before booster vaccination, 96.85%-97.64% participants in NVSI-06-09 group, and 95.58–97.99% in BBIBP-CorV group had detectable nAbs against the Omicron BA.2, BA.4, and BA.5 sub-variants. The anti-BA.2, anti-BA.4, and anti-BA.5 neutralizing baseline GMTs were similar between two groups, i.e., 39.19 (95% CI, 34.27–44.82), 40.59 (35.75–46.10) and 36.95 (32.38–42.16) in the NVSI-06-09 booster group, and 40.35 (35.05–46.45), 42.14 (36.80–48.25), and 34.98 (30.53–40.09) in the BBIBP-CorV booster group (Fig. The cross-neutralizing antibody titers, along with the corresponding four-fold rise rate, against Omicron BA.2, BA.4, and BA.5 induced by the booster vaccination of NVSI-06-09, compared with those boosted with BBIBP-CorV. 