Neutralizing Antibody Response of the Wild-Type/Omicron BA.1 Bivalent Vaccine as the Second Booster Dose against Omicron BA.2 and BA.5
Hitoshi Kawasuji, Yoshitomo Morinaga, Hideki Tani, Yumiko Saga, Hiroshi Yamada, Yoshihiro Yoshida, Yusuke Takegoshi, Makito Kaneda, Yushi Murai, Kou Kimoto, Akitoshi Ueno, Yuki Miyajima, Kentaro Nagaoka, Chikako Ono, Yoshiharu Matsuura, Hideki Niimi, Yoshihiro Yamamoto
Abstract
Although Omicron BA.1-containing bivalent vaccines have been authorized, real-world data validating their safety and antibody responses remain scarce. We conducted a prospective longitudinal study to assess the safety, immunogenicity, and reactogenicity of the second booster dose with the Omicron BA.1 bivalent vaccine in health care workers. Compared with the original monovalent vaccine, the bivalent (WT+BA.1) vaccine elicited higher levels of neutralizing antibodies against the Omicron BA.2 and BA.5 subvariants. The frequency of adverse events after the second booster dose was similar to that of the monovalent vaccine. BA.5-neutralizing antibodies induced by the bivalent Omicron BA.1-containing vaccine were expected to decline. A prospective longitudinal study should be performed to determine the persistence of the humoral immunity.