ABSTRACT
Universal immunization against hepatitis B has contributed to reducing incidence of the disease, but older individuals remain susceptible to acquiring the hepatitis B virus worldwide. Thus, this study aimed to investigate the epidemiology of HBV infection in individuals aged 50 years and over in central Brazil and to evaluate the immunogenicity of the monovalent vaccine against hepatitis B in this age group using two vaccine regimens. METHOD: Initially, a cross-sectional and analytical study was carried out to investigate the epidemiology of hepatitis B. Then, individuals without proof of vaccination for hepatitis B were recruited for a phase IV randomized and controlled clinical trial using two vaccine regimens: Intervention Regimen (IR) (three doses of 40 µg at months 0, 1 and 6) vs. Comparison Regimen (CR) (three doses of 20 µg at months 0, 1 and 6). RESULTS: The overall prevalence of exposure to HBV was 16.6% (95% CI: 14.0%-9.5%). In the clinical trial, statistical differences in protective titers were observed (p = 0.007; IR 96% vs. CR 86%) and the geometric mean of anti-HBs titers was higher in individuals who received the IR (518.2 mIU/mL vs. 260.2 mIU/mL). In addition, the proportion of high responders was higher among those who received the IR (65.3%). CONCLUSION: reinforced doses should be used in individuals aged 50 years or older to overcome the lower efficacy of the vaccine against hepatitis B.
ABSTRACT
BACKGROUND: In recent decades the epidemic of asymptomatic sexually transmitted infections has extended deep into Brazil, including small towns and rural areas. The purpose of this study was to investigate the epidemiology of HIV, syphilis, and hepatitis B (HBV) and hepatitis C viruses (HCV), and to evaluate immunization coverage against hepatitis B in a group of rural workers in Brazil. METHODS: In 2016, a cross-sectional study was conducted with 937 manual sugarcane cutters of the Midwest and Northeast Regions of Brazil. All individuals were interviewed and screened for HIV, syphilis, HBV and HCV. Correlating factors with lifetime HBV infection were investigated using logistic regression. Positive Predictive Values, Negative Predictive Values, sensitivity and specificity were also calculated relative to vaccination against Hepatitis B, comparing anti-HBs titers to vaccination reports. RESULTS: Most reported previous hospitalization (55%), occupational injuries (54%), sharing of personal items (45.8%), alcohol consumption (77.2%), multiple sexual partners in previous 12 months (39.8%), and no condom use during sexual intercourse in last 12 months (46.5%). Only 0.2% reported using injection drugs. Anti-HIV-1 was detected in three individuals (0.3%). Serological markers of lifetime syphilis (treponemal test) were detected in 2.5% (95% CI: 1.6-3.6) of participants, and active syphilis (treponemal test and VDRL) present in 1.2%. No samples were positive for anti-HCV. The prevalence of lifetime HBV infection (current or past infection) was 15.9%, and 0.7% (95% CI 0.4 to 1.5) were HBsAg-positive. Previous hospitalization (OR 1.53, CI 1.05-2.24, p < 0.01) and multiple sexual partners in the last 12 months (OR 1.80, CI 1.25-2.60, p < 0.01) were predictors for lifetime HBV infection. Although 46.7% (95% CI 43.4-49.9) of individuals reported having been vaccinated against hepatitis B, only 20.6% (95% CI 18.1-23.3) showed serological evidence of previous hepatitis B vaccination (positive for anti-HBs alone). CONCLUSIONS: The high prevalence of syphilis and HBV compared to the general population and the high frequency of risk behaviors show the potential for sexual and parenteral dissemination of these agents in this rural population. In addition, the low frequency of hepatitis B vaccinated individuals suggests a need for improved vaccination services.
