Human Papillomavirus Positivity at 3 Anatomical Sites Among Transgender Women in Central Brazil.

BACKGROUND: Transgender women (TGW) are susceptible to the acquisition of sexually transmitted infections (STIs), including human papillomavirus (HPV). Nonetheless, the exact data for this population are scarce. We estimated HPV positivity at the anal, genital, and oral sites among TGW and also identified the related characteristics and behaviors that could be risk factors for HPV infection in a sample of TGW in Brazil. Furthermore, we characterized the site-specific HPV genotypes among those who were positive for HPV at these 3 sites. METHODS: A cross-sectional study was conducted on TGW in Goiânia City (Central-Midwest region), Brazil, between April 2018 and August 2019. Respondent-driven sampling was applied for recruitment. Next, self-collected anal, genital, and oral samples were examined for HPV DNA using polymerase chain reaction (SPF-10 primer). Human papillomavirus genotypes were identified in 12 TGW. RESULTS: In the TGW included in the study, the anal, genital, and oral HPV positivity values were 77.2% (95% confidence interval [CI], 67.3%-84.6%), 33.5% (95% CI, 26.1%-48.9%), and 10.9% (95% CI, 5.8%-17.0%), respectively. In addition, the majority of 12 participants who tested for HPV had multiple genotypes. HPV-52 was the most prevalent genotype identified at the anal (66.6%) and genital (40.0%) sites, whereas HPV-62 and HPV-66 were the most common at the oral site (25.0%). CONCLUSIONS: A high HPV positivity was observed among TGW. Therefore, additional epidemiological studies on HPV genotypes should generate health intervention information, including the prevention, diagnosis, and treatment of sexually transmitted infections.

Molecular and epidemiological aspects of hepatitis C virus infection among crack cocaine users.

The aim is to investigate the prevalence, risk factors, and hepatitis C virus (HCV) genotypes/subtypes among crack users in-treatment in Central Brazil. A cross-sectional survey in which 600 in-treatment crack users were interviewed and tested for anti-HCV Ab by enzyme-linked immunosorbent assay was conducted between August 2012 and April 2013. Anti-HCV-positive samples were also submitted for HCV RNA detection by polymerase chain reaction. Positive HCV RNA samples were genotyped by direct sequencing analysis of the NS5B region of the viral genome, followed by phylogenetic analysis. Of the total, 3.7% (95.0% CI, 2.4%-5.6%) were anti-HCV positive. Age over 40 years and history of injecting drugs were risk factors for HCV, while snorting cocaine was a protector variable. HCV RNA was detected in 14 of 22 anti-HCV-positive samples, and the genotypes 1 (n = 10) and 3 (n = 2), subtypes 1a (n = 7), 1b (n = 3), and 3a (n = 2) were identified. The HCV prevalence found among crack users is almost threefold that observed in the general population in Brazil supporting that this population is at higher risk for HCV. The findings of cocaine insufflation as a protective behavior for HCV infection in this population should be explored.

Epidemiology of HIV, syphilis, and hepatitis B and C among manual cane cutters in low-income regions of Brazil.

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.

Gender differences in patterns of drug use and sexual risky behaviour among crack cocaine users in Central Brazil.

BACKGROUND: The aim of this study was to compare sociodemographic characteristics, patterns of drug use, and risky sexual behaviour among female and male users of crack cocaine. METHODS: Between 2012 and 2013, we conducted a cross-sectional study of 919 crack cocaine users (783 men and 136 women) in Central Brazil using face-to-face interviews. Blood samples were collected to test for syphilis. The Chi-Square Automatic Interaction Detector (CHAID) was used to explore the differences between genders. We implemented two models: the first model included previous incarceration and variables related to patterns of drug use, and the second model included variables related to sexual risky behaviours and syphilis exposure. RESULTS: Women consumed more crack cocaine than men on a regular basis; however, poly-drug use was more common among men. More women than men reported exchanging sex for money and/or drugs and inconsistent condom use during sexual intercourse; women also reported more sexual partners. In addition, the frequency of sexual violence was higher for women than men. A higher proportion of women than men were positive for syphilis (27.2% vs. 9.2%; p < 0.001). The CHAID decision tree analysis identified seven variables that differentiated the genders: previous incarceration, marijuana use, daily crack cocaine consumption, age at first illicit drug use, sexual violence, exchange of sex for money and/or drugs, and syphilis exposure. CONCLUSION: Our findings demonstrate a difference in patterns of crack cocaine consumption and sexual risky behaviours between genders, thus indicating a need for gender-specific interventions in this population.

Factors related to the perceived stigmatization of people living with HIV.

OBJECTIVE: Analyzing the factors related to perceived stigmatization of people living with HIV. METHOD: A cross-sectional study conducted from September of 2014 to December 2015 with users from a specialized service in Minas Gerais. Data were collected through individual instrument application, organized in Microsoft Office Excel(r) 2010 spreadsheets and processed on IBM(r) SPSS 23.0. Descriptive statistics and multiple linear regression method were used for data analysis, adopting statistical significance set at 5.0% (p≤0.05). The study development met research ethics standards. RESULTS: 258 users participated in the study. Most were males between 40 and 49 years of age, single, with low educational level and income. Being between 40 and 49 years of age and having been hospitalized for complications related to HIV were positively associated predictors to increased stigmatization; while not having comorbidities and not being aware of exposure to HIV were predictors associated to reduced stigmatization. CONCLUSION: Given these results, we highlight that stigmatization can have an impact on the lives of people living with HIV, strengthening their feelings of guilt and shame, which can lead to depression, social isolation and abandoning treatment and clinical follow-up.

Factors associated with HIV prevalence in a prison population. / Fatores associados à prevalência do vírus da imunodeficiência humana em população privada de liberdade.

OBJECTIVE: To analyze HIV prevalence and associated factors in inmates in a prison in a state in the Northeast region of Brazil. METHOD: Epidemiological, cross-sectional study carried out with prisoners. Interviews were conducted using a form and a rapid test for the diagnosis. Bivariate and multivariate hypothesis testing, with a simple logistic ratio (unadjusted odds ratio) and multiple ratio (adjusted odds ratio) were applied. Significance level was set at p≤0.05. RESULTS: A total of 2,131 inmates participated in the study. The HIV prevalence was 1.0%. Seropositive individuals were mostly Afro-American; their marital status was predominantly single/separated/widower. The mean age was of 31.3 years, and the mean educational level was 6.29 years. There was a link between the HIV virus and the variables: selection of partners based on physical attributes and vaginal sexual intercourse. CONCLUSION: Tackling the HIV infection represents a major challenge for prison and sanitary authorities, considering that the issues related to the HIV context inside and outside the prison environment are interconnected and, therefore, demands coordinated action.

Overt and occult hepatitis B virus infection among treatment-naïve HIV-infected patients in Brazil.

Although hepatitis B virus (HBV) and human immunodeficiency virus (HIV) co-infection is common, only few data are available on HBV among HIV patients including occult hepatitis B infection (OBI), regardless of serological markers. This study aims to determine the prevalence of OBI and overall HBV infection, associated factors, HBV genotypes, and surface (S) gene mutations in a population of treatment-naïve HIV-infected patients in Brazil. A cross-sectional study was conducted in treatment-naïve HIV-infected patients in Central Brazil. All samples were tested for HBV serological markers and HBV DNA. Sequence analysis of the S gene and overlapping polymerase gene was preformed. Overall, 25.1% (127/505) of the patients had markers of current or previous HBV infection, which was associated with age over 40 years, history of injection drug use, and homosexual sex. The hepatitis B surface antigen (HBsAg) seroprevalence was 4.9% (25/505). HBV DNA was detected in 39 out of 505 patients: 20 of them were HBsAg-positive and 19 were HBsAg-negative, resulting in an OBI prevalence of 3.8%. Patients with OBI had significantly higher HCV seropositivity rate compared to HBsAg-positive patients. Sequencing of the S gene revealed Y100C, T131N, and D144A mutations. One patient had the M204I and L180M drug-resistance mutations (polymerase). HBV genotypes A (A1, A2), D (D2, D3), and F (F2) were identified. In conclusion, OBI represented almost half of all HBV infections with detectable HBV DNA, suggesting that hepatitis B diagnosis in HIV patients should include in addition to serological markers the detection of HBV DNA.

Hepatitis E virus infection in patients with acute non-A, non-B, non-C hepatitis in Central Brazil.

Hepatitis E virus (HEV) infection has a worldwide distribution and represents an important cause of acute hepatitis. This study aims to investigate the occurrence of HEV infection and factors associated with this infection in patients with acute non-A, non-B, non-C hepatitis in Central Brazil. From April 2012 to October 2014, a cross-sectional study was conducted among 379 patients with acute non-A, non-B, non-C hepatitis in the City of Goiania, Central Brazil. Serum samples of all patients were tested for serological markers of HEV infection (anti-HEV IgM and IgG) by ELISA. Positive samples were confirmed using immunoblot test. Anti-HEV IgM and IgG positive samples were tested for HEV RNA. Of the 379 serum samples, one (0.3%) and 20 (5.3%) were positive for anti-HEV IgM and IgG, respectively. HEV RNA was not found in any sample positive for IgM and/or IgG anti-HEV. After multivariate analysis, low education level was independently associated with HEV seropositivity (p = 0.005), as well as living in rural area, with a borderline p-value (p = 0.056). In conclusion, HEV may be responsible for sporadic self-limited cases of acute hepatitis in Central Brazil.

Syphilis infection, sexual practices and bisexual behaviour among men who have sex with men and transgender women: a cross-sectional study.

OBJECTIVES: Men who have sex with men (MSM) and transgender women (TW) are highly vulnerable groups to sexually transmitted infections (STIs). This study aims to assess the prevalence of syphilis infection, sexual behaviour and identify factors associated with syphilis in MSM and TW in Campo Grande, Central Brazil. METHODS: Between 2009 and 2011, 430 MSM/TW participants were interviewed and tested for syphilis. Univariable and multivariable regression analyses were done to assess associations with syphilis infection. RESULTS: A total of 430 MSM/TW (278 MSM and 152 TW) were included in the study. The overall prevalence of lifetime syphilis and active syphilis was 34.7% (26.3% among MSM; 50.0% among TW) and 17.5% (12.3% among MSM; 27.0% among TW), respectively (p<0.001). In multivariable regression analysis, being 20-24 years and ≥30 years, having engaged in a variety of sexual practices and with a history of genital/anal ulcer in the last 12 months were associated with lifetime syphilis infection in the MSM group. Among TW participants, being ≥30 years of age, having more than 10 male sexual partners in last week and being infected with HIV were associated with lifetime syphilis. Factors associated with active syphilis among MSM were massage parlour/sauna recruitment and alcohol consumption at least once a week. Having sex with female partners in the past 12 months was predictive for active syphilis among TW. CONCLUSIONS: The prevalence of syphilis infection and risk sexual behaviour were high in the two samples, especially among TW. High levels of bisexual behaviours and low rates of consistent condom use indicate potential HIV/STIs transmission into the heterosexual population. This finding indicates the need and urgency for implementing more effective integrated programmes targeting MSM/TW for the prevention of syphilis and other STIs.

Prevalence and genetic characterisation of HTLV-1 and 2 dual infections in patients with pulmonary tuberculosis in Central-West Brazil.

Human T-cell lymphotropic virus (HTLV) may impact the clinical course of tuberculosis (TB). Both infections are highly endemic in Brazil. The aim of this study was to assess the prevalence of HTLV-1/2 in TB patients in Central-West Brazil and to perform a genetic characterisation of the respective isolates. Of the 402 patients, six (1.49%) were positive for anti-HTLV and five (1.24%; 95% confidence interval: 0.46-3.05) were infected with HTLV-1/2. Genetic characterisation demonstrated that the four HTLV-1 isolates belonged to the Transcontinental subgroup A of the Cosmopolitan subtype a and that the HTLV-2 isolate belonged to subtype a (HTLV-2a/c). The prevalence of HTLV infection observed in this study is higher than that observed in local blood donors and the HTLV-1 and 2 subtypes identified are consistent with those circulating in Brazil.

Outreach hepatitis B vaccination of female sex workers in central-west Brazil: immunization status, compliance, and immune response.

OBJECTIVES: To evaluate the hepatitis B immunization status of female sex workers (FSWs) in Central-West Brazil and to evaluate their compliance with and immune response to hepatitis B vaccination delivered using outreach strategies. METHODS: A total of 721 FSWs recruited in 2 large cities in Central-West Brazil were interviewed and screened for the presence of hepatitis B virus (HBV) markers. Hepatitis B vaccine was offered to all women susceptible to HBV, using outreach strategies. The immune response of FSWs who received a full course of vaccine was assessed following the final vaccine dose. RESULTS: We found that 27.6% of FSWs, the majority of whom were aged 18 to 25 years, had serological evidence of previous hepatitis B vaccination. A total of 434 FSWs were eligible for vaccination, 389 (89.6%) of whom accepted the first hepatitis B vaccine dose. Of those, 64% received a second dose and 37.5% received all three doses. Through the outreach strategy, there was a 52.2% increase in the number of women who received the second dose and a 67% increase in the number who received the third dose. Of the 146 women who received a full course of vaccine, 105 accepted testing for quantitative anti-HBs (hepatitis B surface antibody) following the final vaccine dose, and 92.4% of those tested had developed protective levels of anti-HBs. Lower education level, workplace, and length of prostitution were predictors of full-vaccine acceptance. CONCLUSIONS: The present findings illustrate the benefits of using outreach strategies to overcome the difficulties of vaccinating hard-to-reach populations such as FSWs.

Getting knowledge to provide care: prevalence and factors associated with Sexually Transmitted Infections in immigrants from Goiás.

OBJECTIVE: To estimate the prevalence of Sexually Transmitted Infections (STIs) in immigrants and refugees living in the metropolitan region of Goiânia, Goiás. METHOD: This is a cross-sectional and analytical study. Data collection was carried out from July 2019 to January 2020 and 308 immigrants and refugees were included in the sample. All were underwent face-to-face interviews and were tested for HIV, Syphilis, and Hepatitis B, using rapid tests. RESULTS: The general prevalence for any of the STIs investigated was 8.8% (95%CI 6.0% - 12.3%), being 5.8% (95%CI 3.6% - 8.9%) for Hepatitis B, 2.3% for Syphilis (95%CI 1.00% - 4.4%) and 0.7% for HIV (95%CI 0.1% - 2.1%). Multiple analysis, using logistic regression, showed that the variables male gender (OR = 2.7) and length of time living in Brazil (OR = 2.6) were significantly associated with STIs (p < 0.05). CONCLUSION: The results of this study suggest that STIs are a health problem in immigrants/refugees, which appear to be enhanced with the length of migration in the country. Public policies that guarantee health care for this population shall be considered.

Cocaine/crack and cannabis use among transgender women in Goiás, Central Brazil.

INTRODUCTION: Illicit drug use is a significant public health problem. Studies have shown a high prevalence of cocaine and cannabis use in transgender women (TGW). OBJECTIVE: To describe the consumption patterns of cannabis and cocaine/crack use and variables associated with their use in TGW in Central Brazil. METHODS: A cross-sectional study was conducted on TGW in Goiás, Brazil. Participants were recruited using a respondent-driven sampling method and were interviewed face-to-face about cannabis and crack-cocaine and the variables associated with them. The Alcohol Smoking and Substance Involvement Screening Test was used to assess substance use. Unweighted logistic regression was used to identify variables associated with cannabis and crack cocaine use. P-values < 0.05 were considered statistically significant. RESULTS: A total of 440 transgender women participated in the study. Their median age was 25 years (interquartile range: 20.5-29.5 years). Most participants were single (85.5%) and had engaged in sex work in their lifetime (58.6%). Cannabis was reported by 68.9% and 53.4% of participants in their lifetime and in the past three months, respectively, and cocaine/crack use was reported by 59.8% and 44.1% of participants in their lifetime and the past three months, respectively. Of the participants, 10.2% reported high-risk cannabis use, and 9.1% reported high-risk cocaine/crack use. Furthermore, 35% of participants reported using both drugs. Previous physical violence (Adjusted Odds Ratio (AOR): 2.37), inconsistent condom uses during anal sex (AOR: 2.17), and moderate-/high-risk cocaine/crack use (AOR: 3.14) were associated with high-risk cannabis use. Previous sexual violence (AOR: 2.84), previous STI (AOR: 2.90), moderate-/high-risk cannabis (AOR: 3.82), and binge drinking (AOR; 3.28) were associated with high-risk cocaine/crack use. CONCLUSION: Our study found a high frequency, significant overlap in the use of cannabis and cocaine/crack use and violence associated with these drugs consumption among TGW, highlighting the urgent need for health policies for drug disorders among this socially marginalized group.

Alarming patterns of moderate and high-risk alcohol use among transgender women in Goiás, Central Brazil.

Background: Scant studies have examined alcohol consumption among transgender women in Latin America. This cross-sectional study estimated the prevalence and associated factors of risky alcohol use among transgender women in Goiás, a state located in the center of Brazil. Methods: Participants were 440 transgender women (median age = 35 years, interquartile range = 9) recruited through respondent-driven sampling. All participants were interviewed about sociodemographic characteristics, violence, and risk behavior. Alcohol use was assessed using the alcohol use disorders identification test (AUDIT). An AUDIT score greater than or equal to eight was considered as risky alcohol consumption. Logistic regression analysis was used to examine predictors of risky alcohol use, and p-values <0.05 were considered significant. Results: The majority were young, single, sex workers. Most transgender women had used alcohol in the previous year (85.7%), and more than half (56.6%) reported binge drinking and risky alcohol consumption (60.2%). There was a high overlap between sexual behavior, drugs, and alcohol use. Using alcohol during sex (adjusted odds ratio [aOR]: 2.9; 95% confidence interval [CI]: 1.7-4.8), cocaine/crack use (aOR: 2.3; 95% CI: 1.5-3.7) and having a drug user as a sexual partner (aOR: 2.9; 95% CI: 1.5-5.9) were independently associated with risky alcohol consumption. Conclusion: Alcohol consumption was highly prevalent, and drugs seem to play an important role in risky alcohol consumption among transgender women Goiás. These findings support stakeholders to promote intervention strategies to reduce this pattern of alcohol consumption and reduce the burden of substance use disorders among transgender women.

Prevalence of hepatitis C virus infection among recyclable waste collectors in Central-West Brazil.

The prevalence of hepatitis C virus (HCV) in a population of recyclable waste collectors (n = 431) was assessed using a cross-sectional survey in all 15 cooperatives in the city of Goiânia, Central-West Brazil. The HCV prevalence was 1.6% (95% confidence interval: 0.6-3.6) and a history of sexually transmitted infections was independently associated with this infection. HCV RNA (corresponding to genotype 1; subtypes 1a and 1b) was detected in five/seven anti-HCV-positive samples. Although the study population reported a high rate (47.3%) of sharps and needle accidents, HCV infection was not more frequent in recyclable waste collectors than in the general Brazilian population.

Occult hepatitis B virus infection among injecting drug users in the Central-West Region of Brazil.

The prevalence of occult hepatitis B virus (HBV) infection was investigated in 149 hepatitis B surface antigen (HBsAg) negative injecting drug users (IDUs) in the Central-West Region of Brazil. Of these individuals, 19 were positive for HBV DNA, resulting in an occult HBV infection prevalence of 12.7% (19/149); six of these 19 individuals had anti-HBV core and/or anti-HBV surface antibodies and 13 were negative for HBV markers. All IDUs with occult hepatitis B reported sexual and/or parenteral risk behaviours. All HBV DNA-positive samples were successfully genotyped. Genotype D was the most common (17/19), followed by genotype A (2/19). These findings reveal a high prevalence of occult HBV infection and the predominance of genotype D among IDUs in Brazil's Central-West Region.

Hepatitis E Prevalence in Vulnerable Populations in Goiânia, Central Brazil.

A transversal study was conducted among 472 vulnerable individuals (recyclable waste pickers, immigrants and refugees, homeless individuals, as well as lesbian, gay, bisexual, and transexual individuals) in Goiânia City, the capital of the State of Goiás, Brazil, to investigate the prevalence of hepatitis E virus (HEV) infection. A total of 459 (97.2%) serum samples were tested for anti-HEV IgG and IgM antibodies using fully automated chemiluminescence immunoassays (Liaison® Murex Anti-HEV IgG and IgM assays, DiaSorin, Saluggia, Italy). Positive samples were tested for the presence of HEV RNA by a real-time polymerase chain reaction. A seroprevalence of 0.87% (95% confidence interval [CI]: 0.34-2.22) was found for anti-HEV IgG. Furthermore, anti-HEV IgM was detected in only one individual (0.22%; 95% CI: 0.04-1.22), who was also negative for HEV RNA. These findings revealed that HEV infection is infrequent in vulnerable individuals in Central Brazil, with low seroprevalence of past and recent HEV infections.

Low Vaccine Coverage and Factors Associated with Incomplete Childhood Immunization in Racial/Ethnic Minorities and Rural Groups, Central Brazil.

Discrimination and limited access to healthcare services in remote areas can affect vaccination coverage. Therefore, this study aimed to estimate vaccination coverage for children living in quilombola communities and rural settlements in the central region of Brazil during their first year of life and to analyze the factors associated with incomplete vaccination. An analytical cross-sectional study was conducted on children born between 2015 and 2017. The percentage of children who received all vaccines recommended by the National Immunization Program in Brazil by 11 months and 29 days was used to calculate immunization coverage. Children who received the following vaccines were considered as having a complete basic vaccination schedule: one dose of BCG; three doses of Hepatitis B, of Diphtheria-Tetanus-Pertussis (DPT), of Haemophilus influenzae type b (Hib), and of Poliovirus (Polio); two doses of Rotavirus, of 10-valent pneumococcal (PCV10), and of Serogroup C meningococcal conjugate (MenC); and one dose of Yellow Fever (YF). Measles-mumps-rubella (MMR) and other doses recommended at or after 12 months were not included. Consolidated logistic regression was used to identify factors associated with incomplete vaccination coverage. Overall vaccination coverage was 52.8% (95% CI: 45.5-59.9%) and ranged from 70.4% for the Yellow Fever vaccine to 78.3% for the Rotavirus vaccine, with no significant differences between the quilombola and settler groups. Notably, the likelihood of incomplete general vaccination coverage was higher among children who did not receive a visit from a healthcare professional. Urgent strategies are required to achieve and ensure health equity for this unique and traditionally distinct group with low vaccination coverage.

Prevalence, Risk Factors and Vaccine Response against Hepatitis B in People Aged 50 Years or Older.

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.