PI-050 - INFLUENCE OF ALDH2 RS671 POLYMORPHISM ON ANTIBODY TITER AFTER INFLUENZA VACCINATION: A PROSPECTIVE OBSERVATIONAL STUDY

T. Yoshihara¹, T. Eto², J. Manabe¹, Y. Miura¹, H. Kumashiro³, A. Melli³, S. Matsuki¹, S. Irie³, Y. Hirota³; ¹SOUSEIKAI Fukuoka Mirai Hospital, Fukuoka, Japan, ²SOUSEIKAI Hakata Clinic, Fukuoka, Japan, ³SOUSEIKAI, Fukuoka, Japan.

Background: Aldehyde dehydrogenase 2 (ALDH2) is an enzyme that metabolizes aldehydes and alcohol. The ALDH2 rs671 polymorphism (*2) causes significantly reduced ALDH2 activity compared to the wild-type genotype (*1), and the frequency of this variant is high (approximately 30-50 %) in East Asia, including Japan. Recently, it was reported that the increase in IgG antibody titers after COVID-19 vaccination was lower in *2 carriers than *1 carriers. Although the mechanism is unknown, it has been suggested that the polymorphism may be associated with CD4-positive T cell-mediated immune responses. Since there are reports that influenza vaccination induces CD4-positive T cells, it is conceivable that the polymorphism may also be involved in the attenuation of antibody titer after influenza vaccination. This study evaluated the association between the polymorphism and hemagglutination inhibition (HI) antibody titer after influenza vaccination.

Methods: The blood samples of 125 participants (92 females and 33 males aged 24-­74 years), 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 titer to influenza A/H1N1, A/H3N2, B/Yamagata, and B/Victoria were measured. Due to the small number of ALDH2 *2/*2 subjects, 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 4 and 12 weeks 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). In 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.