At the SARS-CoV-2 pandemic when the Omicron BA.5 variant dominates, viral-neutralizing titers against wild-type, Omicron BA.1, BA.2, and BA.5 variants were measured using pseudovirus assay for comparison. Serum samples from 12 participants (n = 7 for 18–65 years; n = 5 for 65–85 years) collected at 14 days post-booster were subjected to pseudovirus-luciferase neutralization assay. (A) Wuhan wild type WT, BA.1, BA.2, and BA.5 for study participants of all ages, (B) WT vs. BA.1 for young adults and the elderly, (C) WT vs. BA.2 for young adults and the elderly, and (D) WT vs. BA.5 for young adults and the elderly. The 50% viral-neutralizing antibody geometric mean titers (GMT, 95% CI) were measured, pVNT50. Statistical analysis was performed by the Student’s t-test (ns, p>0.05; ****, p<0.0001). No significant difference is notable between the two age groups in neutralization effect against WT, BA.1, BA.2, and BA.5.