Long-term humoral and cellular immunity against vaccine strains and Omicron subvariants (BQ.1.1, BN.1, XBB.1, and EG.5) after bivalent COVID-19 vaccination

• DOI: 10.3389/fimmu.2024.1385135
• Publication Date: 2024-05-02T04:48:19Z
• Authors: Hakjun Hyun; Eliel Nham; Hye Seong; Jin Gu Yoon; Ji Yun Noh; Hee Jin Cheong; Woo Joo Kim; Sun Kyung Yoon; Se-Jin Park; WonSeok Gwak; June-Woo Lee; Byoungguk Kim; Joon Young Song
• Keywords: Bivalent (engine); Humoral immunity

Background The assessment of long-term humoral and cellular immunity post-vaccination is crucial for establishing an optimal vaccination strategy. Methods This prospective cohort study evaluated adults (≥18 years) who received a BA.4/5 bivalent vaccine. We measured the anti-receptor binding domain immunoglobulin G antibody neutralizing antibodies (NAb) against wild-type Omicron subvariants (BA.5, BQ.1.1, BN.1, XBB.1 EG.5) up to 9 months post-vaccination. T-cell immune responses were before 4 weeks after vaccination. Results A total 108 (28 SARS-CoV-2-naïve 80 previously infected) participants enrolled. Anti-receptor (U/mL) levels higher at than baseline in SAR-CoV-2-naïve individuals (8,339 vs. 1,834, p<0.001). NAb titers significantly both groups, whereas EG.5 was negligible all time points. response (median spot forming unit/10 6 cells) highly cross-reactive (wild-type/BA.5/XBB.1.5, 38.3/52.5/45.0 individuals; 51.6/54.9/54.9 SARS-CoV-2-infected individuals) post-vaccination, with insignificant boosting Conclusion Remarkable neutralization observed vaccination, but not EG.5. cross-reactive.