Examination of antibody titer against Omicron type SARS-CoV-2 BQ.1.1 variant and XBB variant in Japan

To verify the antiviral effect of the mRNA-based COVID-19 vaccine (BNT162b2) against the Omicron type SARS-CoV-2 BQ.1.1 variant and the XBB variant, our medical team investigated the neutralizing activity of antibodies* in plasma of BNT162b2 vaccinated individuals against BQ.1.1 variant and XBB variant isolated from Omicron type SARS-CoV-2 infected patients. As a result, compared with the neutralizing activity of plasma antibodies against the conventional strain, BA.2 variant, or BA.5 variant, the neutralizing activity of plasma antibodies against BQ.1.1 variant and XBB variant was significantly turned out to be low.

Furthermore, our research team examined the neutralizing activity of antibodies in the plasma of patients infected with the BA.2 variant after the third dose of BNT162b2 (i.e., the BA.2 variant breakthrough infection) against the BQ.1.1 variant and the XBB variant. As a result, compared with the neutralizing activity of plasma antibodies against the conventional strain, BA.2 variant, or BA.5 variant, the neutralizing activity of these plasma antibodies against BQ.1.1 variant and XBB variant was found to be significantly lower. However, most of the antibodies in plasma were found to have neutralizing activity against BQ.1.1 variant and XBB variant, albeit at a low level.

Clinical studies used the antibodies in plasma from children (aged 5–11 years) 1–2 months after the third dose of BNT162b2 and the antibodies in plasma from children infected with the BA.2 variant (aged 5–11 years) after the third dose of BNT162b2 (the BA.2 variant breakthrough infection).

We do not have potential conflicts of interest.

Doctor specializing in cancer care/Doctor specializing in emerging infectious diseases

Published on JAMA Pediatrics in Jan. 22, 2023. by Kyoto@takumaH