Universal HBV vaccination had not been available in Japan until 2016 and men who have sex with men (MSM) are still vulnerable to hepatitis B virus (HBV) infection. Thus, we evaluated incidence of HBV infection and prophylactic effect of pre-exposure prophylaxis (PrEP) with tenofovir disoproxil fumarate (TDF/FTC) against HBV infection among a non HIV-infected MSM cohort, sexual health clinic (SHC) in Tokyo.
MSM over 16 years old were included in SHC cohort. Participants were examined for HIV infection, syphilis (quantitative RPR/TPHA), pharyngeal and rectal Chlamydia trachomatis and Neisseria gonorrhoeae infections, and HBs antigen/antibody and HBc antibody, HCV antibody and HAV IgG antibody every 3 months. Entry criteria of the study were HBc antibody negative (< 1.0 S/CO CLIA method) and HIV negative at the study enrollment. TDF/FTC for PrEP were provided for free via an official program of daily PrEP or purchased via internet for its generic drug at their own expense. The definition of HBV infection was positive conversion of HBc antibody or HBs antigen during follow-up period. The participants were followed between January 2018 and September 2019 and incidence rate of HBV infection were evaluated. Participants who acquired HBV infection or HIV infection were censored. Use of vaccination of HBV were defined as self-report of their experience of HBV vaccination or HBs antibody >= 10 mIU/ml (CLIA method). The cox proportional hazards regression analysis was used to evaluate prophylactic effect of PrEP against HBV infection and other factors including HBV vaccination. Factors with statistically significance (p<0.05) and the use of HBV vaccination as a known preventive factor against HBV infection were entered into multivariate analysis.
827 MSM were included in the cohort as of September 2019. Of 827 MSM, 25 and 211 MSM were excluded from the study due to HIV infection and HBc antibody positivity at the enrollment, respectively. 591 (148 were PrEP+ and 443 were PrEP-) were followed every 3 months with 419.8 person-years [mean age (SD), 34.5 years (9.3)]. The incidence rate of HBV infection was 3.57 cases per 100 person-years (15 HBV infections, one in the PrEP+ group and 14 in the PrEP- group, Log Rank test p=0.012,). The table identified the preventive and risk factors estimated by the cox hazard analysis which showed significant prophylactic effect of PrEP against HBV infection.
PrEP is a good indication especially for non-responders to HBV vaccination among MSM.