E# INFLUENCE OF ALDH2 RS671 POLYMORPHISM ON ANTIBODY TITER AFTER INFLUENZA VACCINATION: A PROSPECTIVE OBSERVATIONAL STUDY

Abstract

This study was presented at the 2025 ASCPT annual meeting under the same title. BACKGROUND: Aldehyde dehydrogenase 2 (ALDH2) is an enzyme that metabolizes alcohol. The ALDH2 rs671 polymorphism (*2) significantly reduces ALDH2 activity compared to the wild-type genotype (*1), and the frequency of this variant is high in Japan. Recently, it was reported that the increase in IgG antibody titers after COVID-19 vaccination was lower in *2 carriers than *1 carriers. This study evaluated the association between the polymorphism and hemagglutination inhibition (HI) antibody titer after influenza vaccination. METHODS: The blood samples of 125 participants, who received the influenza vaccine for the 2023/2024 season, were collected before (S0), 4 weeks after (S1), and 12 weeks after vaccination (S2). HI antibody titers to influenza A/H1N1, A/H3N2, B/Yamagata, and B/Victoria were measured. Data were compared between 2 groups: the *1 group (*1/*1: 71), and the combined *2 group (*1/*2: 49, *2/*2: 5). RESULTS: In A/H1N1 and B/Yamagata antibody titers, the post-vaccination changes in antibody titers were not different between the 2 groups. In A/H3N2 antibody titers, the seroconversion rate (S2/S0≧4 and S2≧1:40) was significantly higher in the *1 group compared to the *2 group (19.7％vs 7.4％, p=0.04). In B/Victoria antibody titers, the percentages of those with antibody titers that increased more than 2-fold at S1 and S2 were significantly higher in the *1 group compared to the *2 group (70.4％ vs 53.7％, p=0.04 and 45.1% vs 25.9%, p=0.02, respectively). Regarding the adverse reactions, the percentages of those who developed redness and swelling were significantly higher in the *1 group compared to the *2 group (57.8％ vs 40.7％, p=0.04 and 60.6％ vs 38.9％, p=0.01, respectively). CONCLUSION: This study suggests that ALDH2 *2 carriers may have lower antibody titers and local adverse reaction rates compared to *1/*1 carriers after influenza vaccination.

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