Antibody response elicited by a third boost dose of inactivated SARS-CoV-2 vaccine can neutralize SARS-CoV-2 variants of concern.

Neutralizing antibodies waned significantly six months after two-dose procedure of inactivated SARS-CoV-2 vaccine. However, it is not clear whether a third booster dose could quickly activate the body's immune response against the emerging SARS-CoV-2 variants. This study demonstrated that after a third booster dose of inactivated vaccine, immune memory can be quickly awakened, and the antibody response recovered after seven days. Importantly, although the titers decreased, the neutralizing antibodies at 14 days after the third dose can still neutralize alpha, beta, and delta variants.