Attenuation of hepatitis A antibody after immunization with hepatitis A vaccine (Aimmugen) in people living with HIV

Abstract

Aim: Hepatitis A (HA) is a vaccine-preventable disease. In regions with good sanitation, men who have sex with men (MSM) are the key affected populations. During the 2018–2019 HA outbreak among MSM in Japan, we actively vaccinated MSM living with HIV (MSM-LWHIV) with Aimmugen. As previously reported, their antibody seroconversion rate due to vaccination was lower than that of healthy individuals. However, the durability of Aimmugen in people living with HIV has not yet been reported. We evaluated attenuation after the one-series vaccination (comprising three inoculations) and the factors associated with attenuation. Methods: We retrospectively examined anti-HA immunoglobulin G (anti-HA-IgG) titers and other clinical data from our hospital's medical records. Patients with no history of vaccination or HA infection (i.e., negative HA-IgG titers) who received one series of Aimmugen, achieved seropositivity, and anti-HA-IgG antibodies were tested ≥2 years after three doses were included. Fisher’s exact test and the Mann–Whitney U-test were performed. p < 0.05 was considered statistically significant. Results: Fifty-one MSM-LWHIV were included. All were seropositive after the third dose with a median HA-IgG titer of 10.1 (interquartile range, 7.2–12.2) (sample/cut-off values [s/co]). In 45 (40–49) months, seropositivity decreased to 90% (46/51) and was attenuated to a median of 4.4 (2.3–6.5) s/co. Lower baseline B cell counts (p = 0.049), lower anti-HA-IgG levels after the second dose (p = 0.002), and lower anti-HA-IgG levels after the third dose (p = 0.003) were associated with seronegativity. Conclusions: Anti-HA-IgG titers of vaccinated MSM-LWHIV may be attenuated; thus, additional immunizations should be considered.