Neutralization of SARS-CoV-2 Omicron sublineages by 4 doses of mRNA vaccine.

Since the initial emergence of SARS-CoV-2 Omicron BA.1, several Omicron sublineages have emerged, leading to BA.5 as the current dominant sublineage. Here we report the neutralization of different Omicron sublineages by human sera collected from individuals who had distinct mRNA vaccination and/or BA.1 infection. Four-dose-vaccine sera neutralize the original USA-WA1/2020, Omicron BA.1, BA.2, BA.212.1, BA.3, and BA.4/5 viruses with geometric mean titers (GMTs) of 1554, 357, 236, 236, 165, and 95, respectively; 2-dose-vaccine-plus-BA.1-infection sera exhibit GMTs of 2114, 1705, 730, 961, 813, and 274, respectively; and 3-dose-vaccine-plus-BA.1-infection sera show GMTs of 2962, 2038, 983, 1190, 1019, and 297, respectively. Thus, 4-dose-vaccine elicits the lowest neutralization against BA.5; 2-dose-vaccine-plus-BA.1-infection elicits significantly higher GMTs against Omicron sublineages than 4-dose-vaccine; and 3-dose-vaccine-plus-BA.1-infection elicits slightly higher GMTs (statistically insignificant) than the 2-dose-vaccine-plus-BA.1-infection. Finally, compared with BA.5, the newly emerged BA.2.75 is equally evasive of 4-dose-vaccine-elicited neutralization, but more susceptible to 3-dose-vaccine-plus-BA.1-infection-elicited neutralization.